Archive for January, 2011

AFTER A SUNNY SUNDAY, CLOUDS SHOULD DOMINATE ON MONDAY WITH RAIN LIKELY MONDAY NIGHT AND PART OF TUESDAY… THE COLDEST AIR MASS OF THIS WINTER SEASON IS LIKELY TO SWEEP INTO THE MID-ATLANTIC STATES NEXT WEEKEND

Although Saturday’s weather seemed almost balmy during the afternoon, the fact is that temperatures were normal for this time of year. It has been so cold of late that normal temperatures feel warm by comparison. Sunday will be sunny but northerly winds behind a cold front should lower temperatures a tad. Clouds will be on the increase Sunday night and Monday as a system moves up from the Gulf States. Rain should overspread the region Monday night and it should last through part of Tuesday. Forecasters are predicting that we (Hampton Roads) may see around an inch of rain from this event. Precipitation type shouldn’t be a concern since mild air will be moving in from off of the ocean. We should dry out on Wednesday and then attention will turn to another system that may be more of a forecast problem for meteorologists as this may be a colder system. Forecasters are saying that following that system will come the coldest air of the season. Next weekend may be a frigid one for us. The uncertainty in the extended forecast is determining what areas will receive snow/ice from the potential late week system that will usher in this arctic air mass.  Will it be primarily a Northeast snowstorm or will snow occur further south? Stay tuned on this one. Thanks for reading.

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TEMPERATURES RETURN TO MORE SEASONAL LEVELS THIS WEEKEND… RAIN CHANCES INCREASE MONDAY NIGHT

After a chilly week, temperatures will be more seasonal today (Saturday). Seasonal in mid-January means highs in the upper 40’s and lows around 30. A southwest wind will be transporting in the milder air. A cold front will drop temperatures slightly on Sunday. On Monday, the forecast gets a bit tricky. Computer models diverge on their solutions for Monday. A low pressure system should be heading through the Great Lakes region while another one is expected to be moving along the Southeast Coast. Right now, it appears that most of Monday should remain dry but rain chances will be increasing later in the day. Rain should overspread the area Monday night and continue into Tuesday. Temperatures in Hampton Roads should be warm enough for an all rain event but to our north and west, some sleet can be expected, especially when the precipitation starts. I’ll have an update on Sunday.

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A COMPLEX LOW PRESSURE SYSTEM WILL AFFECT HAMPTON ROADS FROM LATE MONDAY EVENING THROUGH TUESDAY… AS OF MONDAY MORNING, FORECASTERS BELIEVE THAT THIS WILL MOST LIKELY BE MAINLY A RAIN EVENT FOR HAMPTON ROADS WITH SOME SNOW AND SLEET POSSIBLE WHEN THE PRECIPITATION BEGINS

As I’ve been saying for the last several days, forecasters face a major challenge with this rather complex storm system moving northeastward towards the Mid-Atlantic States. As of the time of this writing, forecasters are saying that this will be mostly a rain event for the majority of Hampton Roads. However, some snow and/or sleet may occur at the onset of the precipitation. Due to warm air moving in aloft, rain is expected during most of this precipitation event. There are some significant differences between the expected set-up of this storm and what we saw with the December 26th storm. The details of the differences are quite complicated but the main difference is the previous storm did not have significant warming aloft. This storm system is expected to pull up warmer air for the south just above the surface. That is why rain is anticipated. Areas to our west are expected to have some serious problems with more snow/sleet and some icing. Up to our north, near blizzard conditions may once again impact the Northern Mid-Atlantic States and parts of New England as the storm system intensifies off the coast. I would still monitor your local media and the NWS for any changes in the forecast. It wouldn’t take that much of a change to result in a quick inch or two of snow for Hampton Roads, but right now, that is not the forecast. We shall see how this all turns out. The rest of the week (Wed through Sat)  should be just dry and cold.

Thanks for reading.

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FORECASTERS ARE CLOSELY WATCHING THE STORM SYSTEM THAT IS EXPECTED TO AFFECT HAMPTON ROADS BEGINNING MONDAY NIGHT

Yesterday’s snow squalls were quite impressive. The snow fell heavily for brief periods. The snow bursts were caused by a very cold air aloft causing extreme instability in the atmosphere and literally squeezed out the existing moisture that was in the atmosphere Saturday afternoon. Cold air cannot hold as much water vapor as warm air, so the water vapor precipitates out into snow. This phenomenon is more common up to our north and west. These upper level disturbances were moving around a large polar vortex over New England. Sunday should be sunnier but it will still be a bit breezy. The winds should relax on Monday.

As I stated in my previous post, a major winter storm seems likely for the Mid and North Atlantic States on Tuesday. However, the exact details of where the heaviest snow will be and what areas will see rain mixed in (or possibly all rain) need to be worked out. This storm is really going to be a major forecast challenge as there are so many factors that have to be considered with this system. Here’s what forecasters think is going to happen. A low pressure area is going to develop in the Northern Gulf of Mexico on Monday. This cyclogenesis will be caused by an upper level disturbance moving eastward across the deep south. The low will move northeast towards the Carolina coastline. This low pressure system will be quite complex as upper-level energy may cause another low to develop further inland. That will complicate an already complex situation. This system will spread a wintry mix of precipitation across the Tennessee Valley on Monday. The exact track of this system will determine what type of precipitation Hampton Roads receives. If the low tracks further east, snow will be more likely but if it tracks too far offshore, then dry air could reduce precipitation amounts, especially to our north and west. If the low tracks further west, then warmer air will be drawn into the system causing rain instead of snow. Also, with the other low pressure system forming further inland, it could pull in warmer air aloft changing the snow to rain on Tuesday. (See my Weather Fact on why snow is so hard to predict here in Hampton Roads). The low pressure systems are expected to consolidate off the coast of Long Island and really blast Southern New England with a blizzard or near blizzard conditions. NYC may be under the gun again for heavy wind driven snow, just what they really need.

Please monitor your local media and the National Weather Service (NWS) for updates, advisories and warnings that may be issued for the period Monday night through Tuesday night.

 Thanks for reading.

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THE MID-ATLANTIC STATES COULD SEE A SIGNIFICANT WINTER STORM ON TUESDAY… DETAILS ON PRECIPITATION TYPE AND INTENSITY STILL NEED TO BE WORKED OUT… THE WEATHER THIS WEEKEND WILL BE COLD AND BREEZY AT TIMES

A major winter storm seems likely for the Mid and North Atlantic States on Tuesday. However, the exact details of where the heaviest snow will be and what areas will see rain mixed in (or possibly all rain) need to be worked out. This storm is really going to be a major forecast challenge as there are so many factors that have to be considered with this system. Here’s what forecasters think is going to happen. A low pressure area is going to develop in the Northern Gulf of Mexico on Monday. This cyclogenesis will be caused by an upper level disturbance moving eastward across the deep south. The low will intensify as it moves northeast towards the Carolina coastline. This system will spread a wintry mix of precipitation across the Tennessee Valley. The exact track of this system will determine what type of precipitation Hampton Roads receives. If the low tracks further east, snow will be more likely but if it tracks too far offshore, then dry air could reduce precipitation amounts, especially to our north and west. If the low tracks further west, then warmer air will be drawn into the system causing rain instead of snow. (See my Weather Fact on why snow is so hard to predict here in Hampton Roads).

Let’s back up to the weekend. A large polar vortex to our north will keep us on the chilly side this weekend and a developing low offshore will maintain breezy conditions throughout the weekend. Wind speeds should lessen on Monday. Some parts of Eastern VA and NE NC received a little light snow and rain mix overnight Friday night. No major problems were reported.

I’ll have an update on Sunday. Thanks for reading.

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