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!
No comments:
Post a Comment