Plains Severe Threat, Announcements

JBreezy Weather lead forecaster Jaron Breen assisted in the writing of this blog entry, hosted by "The Weather Phenomenon," on this weekend's severe weather threat to the middle of the country.

Stand-by for a possible entry regarding the threat on the newly christened "JBreezy Weather's Occasional-Use Forecast Discussion Blog."

As always, follow me on Facebook and Twitter, where I have almost-daily weather forecasts for State College, PA. I may write a short blurb on the Facebook page instead of a longer entry here.

I have changed the name of this blog to make it more accurate to what I do.

For now, if you have family in the Southern Plains, middle Mississippi Valley, the Southern Lakes, the western Ohio Valley and the northern Kentucky Valley; please alert them of this threat for Friday, Saturday and Sunday. We're expecting a "mini-Outbreak" - not a major one due to low instability, but high shear makes for dangerous storms. Best to be prepared.

-Jaron Breen

8/2/12 - Sunday's Severe Weather

Synopsis

High pressure moving off the coast will allow a south-westerly flow to funnel in a warm, moist air-mass over the coming days. A low-level jet at 5,000 ft (850 mb) will arrive on Sunday and boost the moisture content during the morning - shown on a map as a narrow corridor of enhance precipitable water (two standard deviations above average). Additionally, a surface trough enhanced by UL divergence will bring a line of showers during the afternoon, sunshine could then make a brief return, the new moisture will evaporate, and the air destabilizes again in time for the cold front's arrival during the evening hours. The right-entrance region of a jet streak will arrive at the same time as the front, enhancing the surface-based lifting mechanism from the cold front. Mostly, we're looking at damaging winds, heavy rain, and lightning. Small hail and a brief spin-up cannot be ruled out, but there's really no directional shear around. However, given enhanced moisture and the presence of two lifting mechanisms AND general model agreement between the European and GFS models, the NWS Storm Prediction Center has placed PA, NY, and parts of NJ, OH & western New England - including our area - under a 30% or higher probability for severe weather on Sunday, shown below.

The next outlook for Sunday will be posted on the SPC's outlook website at 3:30 AM Friday.

Models

Below is the output from the 18Z (2 PM EDT) run of the GFS (the American week-long forecast model). I've selected each of the six panels using AccuWeather Professional. From Left to Right then top to bottom: 500 mb Chart showing CCW rotation in two areas, a surface map showing heavy rain, the precipitable water map showing 1.8-2.2 inches in some spots, CAPE (instability), the 850 winds showing speeds of 35 kt (40 mph), and the jet stream winds.

Compare that to the same time using the 12Z (8 AM EDT) runs of the ECMWF (the European week-long forecast model).

The runs are very similar. The trend for CAPE has been downward and we're still three-and-a-half days away from the outbreak. Knowing that the forecast for hours 60-80 by the European model are pretty accurate, I'm going to monitor the trends over the next 24-48 hrs.

I also wanted to share this graphic with you, the GFS Ensembles' (probabilities) consensus vs. average precipitable water.

Orange indicates two standard deviations above average. Cause: the low-level jet.

Conclusion

Things look very good for severe storms on Sunday given that lifting, moisture, instability, and speed shear will be present. If things come together just right, watch out.

8/2/12: TD 5 Discussion

UPDATE (4 AM Friday): Now Tropical Storm Ernesto.

TD 5 (formerly Invest 99L) has formed Wednesday afternoon 800 mi (1300 km) SE of the Antillies. It has become less organized during the evening due to diurnal cooling, influx of dry air & shear on the north side. Here's the forecast scenarios, followed by a note about the intensity and then my forecast.

TRACK

Scenario 1: Heads WNW (280°). Landfall near Dominica Island around noon ET Friday and then hits Jamacia Sunday night. TS-force gusts, rainfall and an angry ocean affect the southern coasts in the northern Caribbean. (NHC Track, GFS model)

• Scenario 1A: Becomes a 75-mph hurricane near Jamacia. Hits Yucitan Peninsula Wed. AM; heads toward Gulf Coast. (Long-Rage GFS)
• Scenario 1B: Turns NE as it nears Jamacia. Hispanola, Cuba, Wrn Bahamas and eventually south FL affected. Will likely stay a TS if this occurs.

Scenario 2: Heads WNW (285-295°). Landfall near Guadeloupe Friday late afternoon and then Hispanola midnight Sat. night into Sunday. Turns NE: Cuba, Srn Bahamas, Straights of FL eventually affected. Puerto Rico could see TS conditions and better chance of heavy rain with this scenario. The storm could weaken after hitting Hispanola and Cuba. (Nrn NHC Track, European Model)

Scenario 3: Neads NE (295-310°). Landfall near Montserrat & Antigua Friday night, near Puerto Rico 24 hrs. later and then follows an Irene-like path through the SE Bahamas. After that, it could either turn N or turn back to the W. (Climatology, Canadian Model)

INTENSITY

I've discussed other intensity probabilities (i.e. becoming a hurricane) above. Just wanted to make it clear that this has a 95% chance of becoming the fifth named storm of the season - Ernesto. Most likely, that's sometime tomorrow (Thursday), but it could be Friday around 19Z at the latest.

MY CALL

Too Early To Tell, but a more northerly route than Scenario 1 makes sense right now. Don't hold me to that; we need dropsonde data. This route is central to 1 & 2 and gives me a few points if climatology is correct. I'll keep you updated, either here or on the Facebook Page.

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FORECASTER: BREEN

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Severe Weather Prediction - posted 6/21/12

I. Moisture

• Precipitable Water - depth of the water if the entire sounding were to support heavy rain
• Theta-E - the temperature of an air parcel if all its water condensed as it was brought down "adiabatically" (without external heating) to 1000 mb
• Moisture Advection - transport of moisture by the wind, usually calculated using dew point, Theta-E, or - in rare cases - Wet-Bulb
• Lifted Condensation Level (LCL) - the height at which an air parcel will reach 100% humidity. Heights below 2 km will increase the likelihood of tornadoes and severe storms. More moisture, lower LCL.

II. Instability: a saturated air parcel that's warmer than its surroundings is unstable and will ascend.

• Level of Free Convection (LFC) - the height at which an air parcel becomes positively bouyant
• Convective Available Potential Energy (CAPE) - the area on a sounding between the level of free convection (LFC, where a saturated air parcel first meets the environmental temperature) and the equilibrium level (EL, where the ascending parcel meets the environmental temperature at higher altitudes). Large values indicate high instability.
• Lifted Index (LI) - the temperature of the environment at 500 mb minus the temperature of the ascending air parcel at 500 mb. Large negative values indicate high instability.
• Lapse Rate - the rate of decrease with height for an atmospheric variable, usually temperature. Negative lapse rates above the LCL may indicate instability.

III. Capping: a lid that prevents storms from forming too early will allow instability to increase. It is usually a layer of warm-air at the top of the boundary layer (the lowest mile of the troposphere).

• Convective Inhibition (CIN or CINS) - the amount of energy required to overcome the negatively buoyant energy the environment exerts on an air parcel. CIN usually is found between the top of the boundary layer/ LCL to the LFC. CIN between -30 and -60 J/kg is optimal for t'storms forming later in the day.
• Inversion - increase in temperature aloft. This is a common type of cap: warm air aloft decreases instability by warming the environment past the parcel's temperature; it is too dense (cool) and will fall as a result.

IV. Forcing Mechanism: something to push air parcels past the cap during the afternoon once stability decreases. Storms cannot form otherwise.

• Surface fronts (boundaries between air masses) create upward motion near the surface.
• Dry lines & cold fronts are the most common boundaries
• Dying thunderstorms produce outflow boundaries that produce localized convergence zones, leading to rising motions and new t'storms to form.
• Moisture Advection in the region between the LCL and LFC will help to bring the height difference to zero, bringing CIN to zero.
• Divergence above the LND is air spreading outwards or increasing speed. The mass must decrease. When air rushes away at high altitudes, air from the surface zooms upward - lift.

V. Wind Shear: a change in the direction and/ or speed of the wind with changing height. Mostly this can be an indicator of how organized the storms will be.

• Storm-Relative Helicity (SRH) - the extent to which helix-like motion occurs (For reference, DNA is in the shape of a double helix.). Horizontal velocity minus storm motion and horizontal relative vorticty (spin) are taken into account from the surface to a few kilometers (up to two miles). This measures the rotation potential in a storm.
• Shear Vector - subtract the wind velocity at one height from another, usually from the surface to six kilometers. This is better for speed shear (increasing or decreasing speed with changing height).

Soundings and Hodographs are great tools in visualizing severe weather scenarios. I'll cover combined indices like STP, Craven-Brooks, and EHI next time.

6/1/12 Outbreak: Only instability was missing, but forcing combined with moisture created the storms. Directional shear was a huge factor as well, leading to tornadoes in some parts of the Mid-Atlantic States.

Mid-Atlantic Tornado Mini-Outbreak - June 1, 2012

PA Tornadoes:

4:25 PM: Hopewell Township, York Co. (EF0)

5:25 PM: Ligonier, Westmoreland, Co. (EF1)

6:18 PM: Alum Bank, Bedford Co. (EF0)

Other:

6:23 PM: Gustnado in Clearfield
- a gustnado is formed when straight-line winds kick up dirt
- the report of a brief tornado by the local fire dept. is the gustnado

Phila. Suburbs: the NWS in Mt. Holly, NJ issued a tornado warning for Montgomery & Bucks counties in PA. No reports of funnel clouds have come in.

MD tornadoes:

2:29 pm: RATED EF0 1 W Damascus Montgomery Co, MD

2:33 pm: FUNNEL CLD 3 SSW Damascus Montgomery Co, MD

2:37 pm: RATED EF0 3 NW Countryside, VA Montgomery Co, MD

3:08 pm: FUNNEL CLD 0.5 S Damascus Montgomery Co, MD

3:09 pm: RATED EF0 2 SSE Damascus Montgomery Co, MD

3:21 pm: RATED EF0? 3 NE Clearview (K2W2) Carrol Co, MD

5:27 pm: FUNNEL CLD Jefferson Frederick Co, MD

5:54 pm: 2 INJ RATED EF1 Pleasant Hills Harford Co, MD

6:08 pm: FUNNEL CLD Severn Anne Arundel Co, MD

7:06 pm: RATED EF0? 1 SSW Fort Meade Anne Arundel Co, MD

7:19 pm: RATED EF0? BWI Airport Anne Arundel Co, MD

8:30 pm: RATED EF0 2 W of Ingleside Queen Anne's Co, MD

VA Tornadoes:

6:33 pm: FNL CLD Centerville Goochland Co, VA

7:00 pm: FNL CLD 1 NNW Gwathmey Hanover Co, VA

7:08 pm: EF0? TRNDO Battlefield Pk Petersburg City, VA

7:16 pm: FNL CLD 2 E Ashland Hanover Co, VA

7:17 pm: EF0 TRNDO 5 ENE Ashland Caroline Co, VA

7:50 pm: WATERSPOUT Winter Harbour Bay ???

8:14 pm: EF1 TRNDO Hampton Hampton City, VA

NC Tornadoes: 3:29 pm: FNL CLD Mackeys Washington Co, NC

5:18 pm: EF0? TRNDO 1 WSW Elizabeth City Pasquotank Co, NC

Some formatting will be required but I'm posting this now.

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June 1st Briefing

I'm calling for an few severe storms to develop in the southeastern quadrant of PA and then a squall line will move through. Look for lightning, heavy rain, winds to 70 mph, hail to an inch and a half in diameter and isolated tornadoes.

I'll have a more detailed outlook around noontime, give or take a couple hours.

May 31st Update: Tomorrow's Severe Storm Potential

Focus Area: Pennsylvania

Synoptic features:
500 mb: Negatively tilted trough
250 mb: Diffluent pattern over SErn PA from splitting branches of the jet stream.
Surface system: occluding mid-latitude cyclone

Mesoscale parameters:
Instability: LOW – SOME PRESENT
Shear: MODERATE – NOT OVERWHELMING

Conclusions:

A squall line associated with the cold front is still the best chance of seeing severe weather across the southern two-thirds of PA. Winds to 70 mph and hail to an inch thick possible. Ahead of the squall line, multi-cell clusters with some isolated super-cell activity are possible due to abundant shear and some instability, but cloud cover lowers probabilities substantially over PA. More breaks in the cloud cover between 10 am and 3 pm are necessary for this scenario to play-out, but there’s a chance of two-inch thick hail and a few isolated yet weak tornadoes if storms form ahead of the squall line.

Other notes:

Thunderstorms will be slow-movers (15-25 kts) with 1-2 inches of precipitable water, increasing the chance of flash flooding from storms. Any storm is also capable of producing dangerous cloud-to-ground lightning.

I will continue to monitor the models and trends. For those of you in the mid-Atlantic States, there is more instability but less shear, so expect clusters of cells and a stronger squall line to organize.

Next entry: Tomorrow by 7:30 AM hopefully.

Acknowledgements: SPC Convective Outlooks and discussions with Steve Simon (grad student) & Scott Sieron (honors ugrad student).

5/30/12 - Friday Severe Weather Scenario

Focus Area: Southern half to two-thirds of PA

Primary threats: Early chance of supercells and multi-cell clusters in the SE quadrant of PA. A squall line will form along the cold front during the afternoon. Timing of the storms will be very similar to yesterday's severe weather.

Instability: Lower than Tuesday
- SB CAPE: About 1000 J/kg (Tuesday's storms developed with similar amount of SB CAPE).
- ML CAPE: About 500 J/kg (Tuesday's storms had up to 2000 J/kg).

Shear: Very high. There was no shear on Tuesday
- 0-1 km SR Helicity = 200-400 m^2 / s^2
- 0-3 km SR Helicity = 250-500 m^2 / s^2
- Jet Stream Presence: CONFIRMED

Synopsis:

The set-up will be similar to Tuesday with notable exceptions.

1. Instability will decrease due to the passage of the warm front occurring on Thursday night and its proximity to the PA-NY border. There will be enough to touch off storms in similar fashion.

2. Shear will be dramatically high since we are near the triple point and close to a jet streak.

3. We're in an area of enhanced upper-level divergence from the jet streak. An upper-level trough at 500 mb (~18,000 ft) will tilt into the low, providing some occlusion -> necessary for severe storms.

Further details (probabilities) to come on Thursday and Thursday night. The SPC has issued a slight risk but if models runs over the next two daily cycles are consistent or the front is expected to move through a bit earlier, a moderate risk of severe could be necessary in one of tomorrow's Day 2 outlooks.

NE US Rainfall - May 7-11, 2012

Short term outlook for the Northeast States.

Flooding rainfall expected over the next five days. Models suggest that rainfall amounts of one to four inches could fall over much of the Northeast US. Thunderstorms on Tuesday and Wednesday could produce heavy rainfall, enhancing totals where storms occur. Also, the SPC is monitoring the region for strong to severe thunderstorms. If you live near rivers or in other areas vulnerable to flooding, take precautions today.

PA T'storm Potential Update - 5.4.12

Fact: Today is the fifth anniversary of the Greensburg, KS tornado that killed 11 people and almost wiped that town off the map.

The following short-term forecast is for central PA.

Slight risk of severe t'storms for most of the Commonwealth.

Sunny, very warm and muggy between now and 2 PM with highs into the 80s dew points in the 60s. Thunderstorms develop after 3 PM and evolve into clusters just like the past few days. Primary threats: rainfall rates to 0.8"/hr and lightning. Other threats: wind gusts (mainly 25-40 mph with isolated speeds to 60 mph) & small hail (pea- to half-dollar-size at the biggest).

Acknowledgements: I was at the NWS in State College from 8:30-10 AM and listened to their brief discussion, which was the motivation for writing this.

Probability of a Watch: less than 15%.

Disclaimer: The forecasts I posted this week and other weeks in the future are my own and not the official forecasts/ opinions of other sources I consult. I will give credit to those sources for the information they provide.

Centre Region Forecast - May 1, 2012

Focus City: State College, PA

Seven-Day Forecast Discussion:

A weak mid-latitude cyclone that touched off isolated thunderstorms last night is currently moving across the Commonwealth today. Cloud cover will begin decreasing. Overnight, high pressure will slide eastward over southern New England, which will be in control of our weather for about 24 hours. A cluster of weak upper-level disturbances (500-mb vorticity maxima) will "bring" a trough (axis of low pressure) northward (showers & storms possible), pushing the high pressure system off the New England coast - all that to occur tomorrow night into Thurs. AM. The trough will settle over southern Upstate NY (near I-90) on Thursday. While near the trough axis (and its zone of mass convergence) on Thursday and Friday, sunny skies may lead to nearby pop-up thunderstorms (the "self-destructing sunshine" effect). On Thursday, a backdoor cold front will head into eastern PA and start to weaken as it heads into the state. But the temperatures east and west of the BDF will be quite different. Two cold fronts will make their way from west to east: one on Friday and another on Saturday... which could lead to showers and thunderstorms each day. Strong storms, while only a remote possibility of occurring, cannot be ruled out entirely. High pressure will move into the area on Sunday, settling over the Northeast US on Monday.

Acknowledgements: I consulted the official discussion from the NWS in State College.

Temperatures: Seventies today and eighties for the second half of the week. Back to the low-to-mid-60s early next week.

Long-term Briefing:

A weak system could be nearby during the middle of next week. Two more systems that look pretty strong could arrive next weekend and in the middle of the following week respectively. In between, look for passing high pressures systems to clear the air for a couple of days.

Brief update

I have some exams so I'll make this quick.

Warm front to slide northeastward today. Showers and storms possible before and during the frontal passage. While in the warm sector, there will be self-destructing sunshine, which may lead to convective showers and storms each day. The best chance of severe weather will be Friday when the cold front approaches. It will be a warm week despite the showery weather, mostly because of sunshine.

Long term: Look out for El Nino and Atlantic ocean blocking to take shape this weekend. I'll have more later.

Brief Update

Focus City: Nowhere specific, but parts of the I-95 and I-77 corridors are a good focus area.

Short term:

Frost and freeze still possible for a few more nights but please continue reading - I have good news:

A shot of tropical air is on tap for the Eastern mid-Atlantic early next week. A cold front may touch off thunderstorms in parts of the Eastern States mid-week. Wednesday's 12Z GFS was pretty favorable for strong storms.

Other models: Euro was fast and Canadian was slow. Both had a less-favored upper-air pattern.

Evaluation: Will watch for trends in 850 mb temps, 1000-500 mb thickness, 300-mb jet streak position, and 500 mb trough tilt. The consistency in GFS Ensemble runs and the Euro/ Canadian with regard to warm-up and cold front passage warrants continued monitoring.

Long-range:

April showers bring may flowers, but April may be relatively dry. With chances for showers/ storms between Saturday and Thursday and about four chances for wet weather in the ten- to sixteen-day forecast, look for those May flowers to have a decent chance to sprout. Keep up with watering in between these chances and you flowers should last.

I will have a more technical version soon. I've had quite a lot of work to do the past few weeks, but will put in some forecasting time this week.

Forecast: Tuesday the 6th & Beyond

No focus area for this discussion. I also would like to mention I am on Spring Break.

Short-term:

An area of high pressure centered near Washington, D.C. will be in control of our weather for the next 36 hours as it slowly slides offshore during that time. A warm front ahead of a mid-latitude cyclone will bring clouds to the region tomorrow and a cold front approaching that night will thicken the cloud cover overnight Wednesday into Thursday and bring a few showers for the day on Thursday, partially enhanced by a weak cut-off low late. High pressure returns for Friday and Saturday, sliding to the east/ northeast during this period. Another cold front/ southern system threatens for early next week.

High temperatures during this period are expected to stay above freezing for highs for much of the Northeast. Over the next few days, the southeasterly flow set-up behind the surface high will push high temperatures to near 70 degrees over the northern half of the mid-Atlantic states and in the upper 50s across the Northeast. The cold front brings temperatures back to near average for the weekend: the 40s and 50s for the mid-Atlantic; the 30s and 40s for the Northeast. Lows will be in the upper 20s to the low 40s; trends are similar when compared to highs: if the highs increase, the lows will most likely increase, and vice versa.

Long-range:

An upper-level ridge will dominate our weather for the long term. The question to be answered is, "When does the upper level flow become zonal over the Northeast U.S.; hence, when do surface cold fronts threaten?" The answer: every five days or so. Therefore, a rather quiet period will result from the ridge over the East, with storms (mostly rain-makers) threatening late next work week, and once or twice the following week.

Oscillations:

Initialization (Currents): In my last entry, I suggested that March, a climatologically favorable month for a big coastal storm, has a less-than 30% chance of that occurring due to unfavorable oceanic oscillations: neutral equatorial-Pacific (ENSO), positive Arctic (AO), phase-2 Madden-Julian (MJO), & no blocking (NAO). Before I go on with the forecast, I want to clarify that the El Nino that is developing is very shallow (hence, very weak). Also, there is still no blocking and a stronger polar jet set-up in Canada is keeping the cold air in the northern U.S.

Forecast: Ensemble forecasting for the oscillations now suggests that the oscillations will now become favorable for a storm, but I am currently unsure whether cold air will move south and linger for long, which has been a common theme for this winter. These forecasts go out to day 15, and at that time, the oscillations mostly return to neutral phase. Beyond that, anything goes. Considering the winter has been above-average temperature-wise & below-average precipitation-wise, the higher sun angle, and the limits & uncertainty of long-term forecasting; the chances of a major East Coast storm are low at this time. The chances are still around 15%, but if in a few days the ensembles do not change, the chance will increase to between 20 & 40 percent.

Conclusion: I cannot conclusively rule out a major storm for March at this time, especially with neutral oscillations. However, given the weak winter we had, I'd put our chances at between 10 & 20 percent for the next four weeks. With favorable forecasts, potentially 50% after the Vernal Equinox.

Later Entries:

I may break down last week's severe weather in an entry this weekend along with a revised Oscillations forecast. I may have a spring seasonal forecast around the time of the Equinox; right now, it looks like an active spring. Of course, I will have the usual short- and long-term forecasts about twice per week.

Sources: Climate Prediction Center for oscillations and the Penn State e-Wall for forecast models.

Have a great rest of the week, everyone! For PSU students, enjoy the rest of your Spring Break!

Friday Night's system

Focus area: Central PA

The cold front will move through around midnight, which is later than severe storms "like." Warm front may not get too far to the north. Instability (CAPE) will be very low to zero. Shear will be quite high.

Evaluation of threat: Rather low to slight -> mostly from dying storms; If near PIT, it is moderate to fairly high.

Guarantees: One thunderstorm, non-severe over most of PA; A strong storm near PIT. Highest instability near PIT & LBE, also near MDT.

Mid-Week & Beyond

There is no focus city but the forecast will look at PA & NY.

Wednesday & Thursday:

Precipitation starts during the morning from West to East as a mix of snow, sleet and freezing rain to the north of the PA turnpike along and east of the Appalachians. Elsewhere, rain will change to thunderstorms in SW PA. The changeover is slower than previously thought: NY and some parts of northern PA along and north of US-6 stays mixed. Between areas north of the PA turnpike and along/ south of I-80, the changeover will occur around 3 PM. Areas in the northern half that see the changeover, sleet could still fall at times. After midnight, the precip. will change to a mix of snow and sleet (light freezing drizzle) for most of PA, at first from the front, but mostly associated with lake-effect during the wee hours.

Leeside troughing causes a weak low to form east of the Delaware & Chesapeake Bays, which heads up the coast late-week.

Thursday Nght into Friday Night:

We get a brief break from wintry precipitation as temperatures recover slightly form the cold front. Some peeks of sun may occur during this period. An area of weak high pressure moves through the northern Mid-Atlantic states during this time.

The Weekend:

A cold front threatens during this period. Expect mostly rain but sleet mixing at the onset is possible.

Next Week:

A short-wave/ area of weak low pressure moves through during the first half. A cold front threatens during the second half of the period.

Beyond the 15-day:

There is a chance for a frontal passage during the period.

Relatively quiet weather is likely to occur considering that previous forecasts this month had about 4-6 systems threaten in the 5-18 days covered by the long-range ensembles.

Oscillations:

Weak El Nino developing; Arctic and North Atlantic Oscillations stay relatively positive. MJO is relatively favorable until early March.

Climatology Note:

March is typically the best month for major winter storms, but the NAO would have to be solidly negative for this scenario to play out. It is not totally out of the question, but my gut tells me there's only a 5-25% chance for an eight-plus-inch snowstorm before April 1.

Show of Shows Weekend

Focus Cities: Atlantic City, NJ (ACY) and Philadelphia, PA (PHL)

Forecast:

Thursday Night (PHL): Cloudy. Chance of showers after midnight. Low 44.
Friday Daytime (PHL): Rain likely early. Thunder possible. Then, cooling with showers likely AND a chance of sleet or frzg. rain, after 2 PM. Cooling down. High 59.
Friday Daytime (ACY): Thundershowers likely. Highs in the mid to upper 60s.
Friday Night (PHL): Mainly cloudy around sunset. Partly cloudy overnight. Windy. Low 34.
Friday Night (ACY): Chance of showers during the evening. Mostly cloudy after midnight. Windy and cooler. Lows in the upper 30s to around 40.
Sat. Daytime (PHL): Mainly sunny early. Mostly cloudy after noonish. Windy and cooler. High 48.
Sat. Daytime (ACY): Mostly sunny for much of the day. Passing clouds during the late afternoon. Windy and colder. Highs in the 40s.
Sat. Night (PHL): Cloudy early; then, mostly clear. Less windy after 11 pm, but still cold. Low 30.
Sat. Night (ACY): Cloudy early; then, mostly clear. Less windy after 3 am, but still cold. Lows in the 20s.
Sunday Daytime (PHL): A mix of clouds and sun early; then, partly sunny after noon. High 45.
Sunday Daytime (ACY): Mostly sunny early; then, partly sunny after 3 pm. Highs around 45.
Sunday Night (PHL): Mostly cloudy. Low 33.
Sunday Night (ACY): Mostly cloudy. Lows in the upper 20s into the low 30s.
Monday Daytime (PHL): Cloudy. Warmer. High 50.

Good luck, Bands!

Feb. 21st to Mar. 9th.

This forecast is of a different format due to reasonable model agreement in the first ten days.

Focus City: Harrisburg, PA

Avg. High/ Low/ Precip: 43-47/ 25-29/ 2.03"

Ten-day forecast:

Tonight through Thursday AM: Isol'd showers, sleet or snow mixed in at night. Highs well into the 50s. Lows in the mid 30s. The precipitation is ahead of a clipper.
Friday: Rain, a chance of thunderstorms during the afternoon. High 63. Rain changing to a mix overnight. Low 30. The cold front will move through during the period. The GFS is faster than the Euro with regards to the front's timing. Given the GFS's tendency for fast solutions, will use the Euro's solution.
Saturday: Light snow from time to time. High 40. Snow tapers during the night. Lows in the upper 20s.
Sunday and Monday: Partly to mostly sunny. Highs in the low 40s. Lows in the upper 20s.

Long-range:

The waning days of February won't pass uneventful as two cold fronts move through next week. Beyond the night of the 29th into March 1st, about four systems could threaten during PSU's spring break the first full week of March - weekends included.

Blog Description

This blog was created by Jaron Breen on February 2nd, 2012.

About the Author

Jaron Breen is a junior at the Pennsylvania State University studying meteorology. He is from the Philadelphia suburbs. He has no clue how he wants to apply his skills after earning his bachelor's degree: he is considering broadcasting & operations and would like to pursue tornado research at some point. Yes, he does want to be a storm chaser. He expects to graduate in either December of 1013 or May of 2014.

The focus for his bachelors degree is to hone his forecasting skills and prepare for a job in broadcasting or operations. He is required to take the following courses: Introductory I & II (completed), thermodynamics (completed), dynamics (taking), synoptics (taking), computer programming (completing), atmospheric measurements, and cloud physics. He will take the following electives with the intent of improving forecasting skills and a preparing for job: Weather Challenge, Mesoscale & Tropical Meteorology, and Weather Communications I & II. He has succeeded in learning Linear Algebra, Vector Calculus, Differential Equations, Statistics, Physics, and Chemistry; and he occasionally tutors students. He is an active member of the Campus Weather Service, managing at least one forecasting shift and one communications shift per semester, giving weather briefings weekly. He is also a student member of the National Weather Association and American Meteorological Society.

Besides the weather, his other interests are Philadelphia sports, particularly the Phillies; Penn State sports such as the football, baseball, soccer, gymnastics, volleyball and basketball teams; and playing the clarinet and saxophone in various groups.

About the Blog

This blog will discuss the short-term forecast and then will go beyond the five-day and attempt to discuss the weather from day six through day seventeen. The focus will be in an Pennsylvania city, most likely State College or Philadelphia, but will discuss weather occurring in other parts of the country.

His Intentions

He would like to apply what he learns in his classes and through forecasting opprotunities with peers and adults at PSU and professionally. He wants to learn how to give seasonal outlooks. In a few semesters, he will add seasonal outlooks to the blog as well. If there is an event predicted for the Eastern half of the country, he may provide forecasts just for the one event.

Soon, I may move this blog to a Google site.

One more thing: he discusses the weather frequently on Facebook, in a group called "Northeastern Storm Trackers." Check it out.

Storm Update

Busted! Sorry for those of you up north... it's going to affect the mid-Atlantic States, not the NE. Was a nice opportunity to learn about nor'easters! A cold front is forecasted in the short term. More on that later.

Hazardous Weather Outlook

Hazardous Weather Outlook (HWO)
The Weather Center of JBreezy
Original Post: 2:47 PM – THURS. Feb. 16th, 2012
Update Posted: 12:20 AM - FRI. Feb. 17th, 2012

This HWO is for much of the Eastern U.S., especially in PA.

Days One and Two: Thursday & Friday

A cold front will exit the Mid-Atlantic States tonight, primarily producing rain. A brief period of snow in the northern portions cannot be ruled out. The front will clear New England by Friday Evening.

Days three through five: Saturday through Monday

A low pressure system located over the SW States will head east toward Texas & Louisiana tonight & tomorrow. After arrival, the upper-level low will open up into the flow to the north. While the exact track remains uncertain, it appears more likely that a nor’easter will head in for early next week. This scenario depends on five things: phasing (the upper-level (UL) cut-off low rejoining the main trough to the north), the Newfoundland low, a weak cold front over the Great Lakes, a surface high in the Eastern Plains, and where the nor’easter is in relation to a jet streak.

The phasing is the biggest factor; the other factors will not matter if phasing is too late. Therefore, until the UL cut-off low opens up tomorrow night, uncertainty will be too great to forecast the nor’easter’s track accurately. On the flip side, most models agree that the low will be in the right place near the jet streak for maximum UL divergence; hence, the surface low will be quite strong.

For now, a 50% or greater probability of 6+” to fall sits approximately from Nashville, TN to the Washington, D.C. area.

Stay tuned for further updates on the possible nor’easter.

Thanks to Brian Edwards from AccuWeather. His discussion was very helpful in creating this.

THON Weekend and Beyond: Part I

Focus City: State College, PA - THON

Short term (Rest of the week and THON weekend):

A couple of mid-latitude cyclones will be moving through the area this week. The first one will produce snow showers (540-Dm 1000-500-mb thickness line and 850-mb, 0-deg.-C Isotherm are south of PA) tonight and tomorrow. After a brief break and a warm-up, the second one will produce rain showers (a mix in some spots) Thursday AM thru Thursday night, and then change to snow showers for the first half of Friday. On Saturday, expect a clipper to move by, but most areas of PA will remain snow-free. High pressure moving in between the systems on Friday and Saturday will briefly stay in south-central PA before the clipper moves in.

Long-term (Storm potential):

It appears that one nor'easter will threaten on Monday AM, with a 36-hour watch period: most likely, it will move off shore well before reaching 40 degrees N latitude. It appears that about four more systems will threaten during the week or two after THON weekend.

I encourage all to go to cws.met.psu.edu and check out the five-day forecast - I run tomorrow afternoon's shift (expect the page to be updated by 5-5:30 PM). I will write another entry before THON - probably Thursday night; hence, why I called this "...Part I." Travel safely if coming up this weekend!!!

Arctic Front and THON Week

Focus City: State College, PA and other portions of the Commonwealth

Average:
High: 33°F; Low: 16°F
Precip:
2.64” liquid
11.1” snow

Short term (CWS/ NWS Seven-Day Forecast):

Hope you all enjoyed the recent snow… more is on the way but not as much. First, we have high pressure in control for the next day or two. A powerful arctic cold front will be making its way southeastward from southern Canada tomorrow night and Friday. Less than an inch of snow is expected with the front despite a short-wave trough forming on the leeward side of the Appalachians. The recent snow was caused by a short-wave trough. Due to the absence of a second high pressure system, the cold spell will be short-lived but powerful: near-average temperatures expected for Saturday and Sunday. Winds will kick up overnight Sat. and last through Sunday, bringing wind chill values to the single digits. A system is coming for the middle of the week. Ahead of it, warm air will start creeping into the area, increasing temperatures for the middle of the week.

Long range (Beyond the Seven-Day):

The GFS and Euro pick up on a coastal storm for the first half THON weekend. While many are dancing for 46 hours in the Bryce Jordan Center fighting pediatric cancer, rain and snow will probably be falling: the 540-Dm 1000-500 mb Thickness line, which statistically coincides with the surface freezing line, bisects the Appalachians. A nor’easter is expected for that Monday the 20th, followed by a similar set-up to this weekend’s storm, which may occur on the 24th. Have a good weekend!

Short-term Outlook: Wed's Snow Event

Short-term: Wed. Snow

GFS Solution;

Timing:

a) Sunrise in Morgantown, WV;
b) 9 am in Pittsburgh, PA;
c) 10 am in State College, PA;
d) noon in Harrisburg, PA - Morgantown, WV flurries;
e) 4 pm E of I-476 - Pittsburgh & Altoona flurries;

Amount: I-77 to I-99 corridors;
a) Total liquid equivalent: 0.12 to 0.21 in.;
b) Potential Snow (8:1): 1.0 to 1.8 in.;
c) Potential Snow (12:1: 1.5 to 2.5 in.;

NAM solution;

Timing:
a) Morgantown, WV: 8:30 am;
b) Pittsburgh, PA: 10:30 am;
c) State College, PA: Noon;
d) Harrisburg, PA: 1:00 pm;
e) Philadelphia, PA: 1:45 pm;

Amount: Mason-Dixon Line from WIL, DE to WHLG, WV;
a) Liquid Eq.: T -> 0.19 in;
b) Sn 8:1 Rat: 0.1 - 1.5 in;
c) Sn 12:1 Rat: 0.1 - 2.3 in;

Go with a GFS & NAM consensus while favoring the GFS at a 10:1 ratio.



Long-range: First Nor'easter;

First scenario: Path takes it near I-10 through Nrn FL;
Second scenario: Path takes it right in the middle of the Gulf;

Near SE Coast, divergent jet stream. Over Gulf = Moisture;

SECOND SCENARIO FAVORED

Nor'easter Fortnight, Anyone?

Focus City: Washington, D.C.
Avg. High: 45°F
Avg. Low: 29°F
Precip: 2.71"

Short term - Three Shortwaves & One Large Trough

The southern branch of the jet stream stretches from central TX to northeastern AR, then along the 36° 30' N parallel to Norfolk, VA and points east. It's width: State College, PA to Charleston, SC. A series of short-waves will change the orientation to SW-NE and combine the southern branch with a strengthening jet streak (now located in central Canada) on Wednesday. A trough will fully develop by the end of the work week. Temperatures will be above average but no higher than the upper 50s.

Each short-wave will produce cloudy skies and a few sprinkles, flurries or freezing drizzle: (1) Wee hours Tuesday; (2) Early Wednesday (best chance for accumulations); and (3) Wee hours Thursday

Long range - FIVE (5) Nor'easters?!!!

Yes, we have five nor'easters in the forecast - all going out to sea. However, it is too far in advance to determine (1) where and when they will affect the mid-Atlantic States AND (2) what precipitation they will produce. The first one is expected for this Sunday afternoon (the 12th) and the last one the model predicts will occur on Tuesday the 21st - NINE DAYS OF NOR'EASTERS. To predict the precipiation type: predict the high and predict the snow.

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-Jaron Breen

First Post: A Tale of Two Patterns

Focus City: State College, PA

Recent event: Phil saw his shadow - not discussed.

Short term Forecast:

High pressure over the upper Midwest in the wake of our latest cold front from Wed. will provide partly to mostly cloudy conditions over much of PA the next five to seven days. Temperatures will be 5-10 degrees above normal: highs 41-46; lows 26-31. Two lows will make their way toward the Delmarva, but the high prevents the two lows from getting anywhere near the State. I cannot rule out clouds in southern PA and a few flurries near KPHL, but more likely than not, we will be dry.

Long range Outlook:

The long-term oceanic oscillations (AO, NAO, ENSO, PNA and MJO) will turn more favorable for East Coast storms in about 6-12 days. Here are the forecasts for 12 days (and the favorable value/ phase for East Coast Storms in parenthesis):

(1) ENSO: El Nino vs. La Nina => weak La Nina (moderate El Nino to weak La Nina)
(2) AO: Arctic Oscillation => slightly negative (negative)
(3) NAO: North Atlantic Oscillation => neutral (negative)
(4) PNA: Pacific North-American => slightly positive (negative)
(5) MJO: Madden-Julian Oscillation => Phases 6-8 (Phases 1,6-8)
(6) PDO: Pacific Decadal Oscillation => Cool Phase (???)

Long range GEFS (Global Ensemble Forecast System) has a nor'easter predicted for hhe night of the 11th into the 12th (a week from tomorrow). It looks to be mostly rain at this point due to high pressure in the mid-Atlantic states; better to have a high over the Great Lakes/ Northeast regions, but it is too far in advance.

Acknowledgements:
(1) Dr. Knight (PA State Climatologist) for the Winter Wx 4csting Lecture tonight
(2) Gabriel Lojero (CWS forecaster) for MJO info.
(3) PSU Campus Weather Service (cws.met.psu.edu) for the five-day forecast
(4) The PSU e-Wall (www.meteo.psu.edu/ewall/ewall.html) for the long-range GFS
(5) NOAA's Climate Prediction Center (www.cpc.ncep.noaa.gov) for Oscillation data