National Weather Person’s Day has been a day not short of excitement with some freezing rain and sleet pellets earlier today. The initial shot of precipitation is departing, but an upper-level low pressure area will be swinging through. It is catching up with the main energy too late to give us a significant winter storm. However, it will pull the infamous “540 Line” down through the Atlantic Ocean tonight and any precipitation it produces in our area will switch from rain to snow and sleet. The most precipitation is projected by the model guidance to be in the northern tier of the region, but the models have backed off on the intensity quite a bit over the past forty-eight hours. Some snow showers could put down a coating in the far north, near Mount Pocono and High Point. Elsewhere, some flakes may fall and dissipate into the puddles. Elsewhere, the colder air will pose a risk for black ice development into early Sunday Morning. The temperatures will drop below freezing down into the Lehigh Valley, Philadelphia Suburbs, Philadelphia Metro, and Central New Jersey. Elsewhere, the clouds will likely limit the drop and temperatures could fall to around 33 or 34 degrees. Some fog will be around until the winds pick up and drier air moves into the area Sunday Morning. After the sun goes down, some of the fog could become locally dense for a few hours.
Sunday will be one of the warmer days of the past two months. Highs will be in the upper thirties with some areas possibly reaching 40 + degrees. It will be mostly sunny. Monday will be sunny in the morning with clouds increasing in the afternoon. Some areas South and East of the city could make a run for 50 degrees. Most of the region could see temperatures as high as 45 or 46 degrees.
A strong cold front will cross the area on Monday Night into Tuesday. The latest 12z & 18z suite of computer modeling guidance shows the column initially warm enough for a mixture of rain and snow or rain. But the cold air advection may catch up with the frontal moisture and quickly change any liquid over to frozen precipitation, in the form of wet snow with perhaps some sleet. The models seem to hint at low pressure developing along this front as it crosses our region which would intensify the precipitation along the boundary. This could cause a six hour period of steady, accumulating snow. The timing of the frontal energy would be critical as if the colder air lags behind, we initially would have more rain than snow. Should the guidance be correct, the cold air would be catching up to us before the balk of the precipitation. This frontal passage will have to be monitored for interaction with moisture coming up from Florida to see if it would generate a coastal low or intensify a low forming on the front further. The frontal passage could usher in some fairly good wind gusts.
Much has been made about a potential winter storm on Thursday. Some of the computer models that were indicating a massive storm with large implications began to back off yesterday. When I see such storms seven to eight days out, I proceed with caution. The models will sometimes dream up these storms; giving snow-lovers the thrill up their leg and then back off. It is very well possible that the models have only temporarily lost this storm, only to bring it back days before impact. The European Model from 12z does show the storm giving the region some snow. The overall climatology favors a large storm on Thursday or Friday. As a normal rule of thumb, I usually do not forecast precipitation for when one of our reliable American models does not show anything more than clouds with a miss of more than five-hundred miles. This is simply a wait and see situation. It does appear a major pattern change is in the works after next week and huge storms thrive off such a change. In March 2010, after weeks of unusually large snowfalls and below normal temperatures, there was a powerful storm that swept through the region. Practically every single day after that storm we observed above average temperatures. The storm brought strong winds to the region and flooding, which combined with a snow-saturated ground to produce widespread tree damage. So the idea of a major storm, not necessarily the one like March that contained rain, is plausible. I also must note that overtime the models this season have shifted the storms to the west as we got closer and this is another reason why the idea of a major storm is NOT off the table. For now, I will play it overcast/stressing that only snow is possible/and we will be updating our forecasts throughout the week. I always like to forecast for the next storm ONLY when the storm before it has swung through and has set the stage for the next one, pattern wise. This means that only by Tuesday Night we should see a clearer picture get revealed. If some of our long range modeling is correct, prior to the pattern change, there could be a very cold outbreak of arctic air by the end of the week.
Check back in around 6:02 p.m. tonight to see the treat for the week for all our site readers! You will enjoy this nice little surprise....we all worked very hard to make this possible during the last month.
In the meantime, I will be over on centralsouthnj.blogspot.com trying to figure out the impact of Tuesday and Thursday for Central and Southern New Jersey!
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