Saturday, February 5, 2011

2/5/2011 Extended Forecast: Active Week Ahead



National Weather Person’s Day is designated as February 5, 2011. This includes weather anchors and those who are meteorologists both in the private and public sector. This is a big holiday for forecasters and a time of celebration. We have come a very long way with forecasting technology over the past few decades. From a television standpoint, stations have gone from the magnets and dry erase boards to green screens and touchscreens. The internet is now making guidance, mapping, and forecasts available to anyone, including amateur forecasters. Accuracy is improving with the ability now to provide a five to seven day outlook. Before 1980, forecasts usually did not exceed 3 days and the accuracy was quite low for day five.

Temperatures this evening are holding in the upper twenties in the highest elevations of Northern New Jersey. In the lower elevations of Northern New Jersey and down into Central New Jersey, mid-thirties are common. In Southern New Jersey, temperatures are in the upper thirties and lower forties. We have a perfect recipe for dense fog as warmer air is moving over the snow-covered ground as the column is full of moisture. Expect ¼ to 1.00 mile visibilities tonight, until the winds begin to pick up.

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 New Jersey, 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 High Point into Bergen County. Elsewhere, some flakes may fall and dissipate into the puddles. As some colder temperatures arrive overnight, there could be some black ice formation.

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 in Southern New Jersey could make a run for 50 degrees. Most of the region could see temperatures as highs as 45 or 46 degrees.

A strong cold front will cross the area on Monday Night into Tuesday. The latest 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. 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.

No comments:

Post a Comment