Weather! Breaking out of the wedge

Canadian high pressure has pinned a cold, damp airmass against the Virginia mountains, keeping most of the state in a rather gloomy pattern. We break out of that pattern in a big way at the beginning of this week. Are you ready for temperatures in the 60s?

January 23, 2012; 12:57 AM • by Weather Dan

Cold air damming – it’s what’s made your weekend wonderfully gloomy.

Meanwhile, I’m in New Orleans attending the 92nd American Meteorological Society annual meeting. While you’ve been dark and gloomy, it’s been in the 70s just about all weekend, with dewpoints to match, meaning it’s not only warm, but very muggy too.

I should have packed shorts. But, I digress.

Sunday’s high at Richmond International was 35. The low Sunday morning was 31. That’s not much variance for a season where the daily high and low typically vary by up to 20 degrees daily. The culprit: the “wedge” of cold air I alluded on on Friday. High pressure over Atlantic Canada has been funneling cool, moist air from the Atlantic Ocean into eastern Virginia. As this air flows from east to west, it gets blocked by any further advancement by the Appalachians. So, it settles over eastern Virginia, and it won’t lift until strong forcing in the upper levels of the atmosphere can begin to push it eastward.

Thankfully, that forcing is coming on Monday in the form of a strong cold frontal boundary currently making its way through the mid-South. At least one tornado has been confirmed in Arkansas Sunday night, and numerous tornado warnings have been issued from Illinois and Kentucky into Tennessee and Arkansas. Systems like this are especially dangerous for everyone, as not only do they spawn tornadoes, the tornadoes tend to be both rain-wrapped (and incredibly hard to spot with the naked eye) and fast-moving, giving people in the path of these storms very little time to react when one is spotted. Additionally, these storms are passing through at night, when any tornadoes are nearly impossible to see, and many people aren’t paying attention to warning sources in the overnight hours.

Shameless plug: get a NOAA Weather Radio, in order to make sure you can hear severe weather alerts at all times of the day and night.

Speaking of all hazards, just because Richmond is stuck under gloomy skies doesn’t mean that we’re hazard-free. A freezing rain advisory is in effect until 6 AM for areas north and west of Richmond, including Goochland, Louisa, Fluvanna, Caroline, and Hanover Counties.

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE WAKEFIELD VA
954 PM EST SUN JAN 22 2012

VAZ048-049-060>064-067>069-231100-
/O.CON.KAKQ.ZR.Y.0001.000000T0000Z-120123T1100Z/
FLUVANNA-LOUISA-PRINCE EDWARD-CUMBERLAND-GOOCHLAND-HANOVER-
CAROLINE-NOTTOWAY-AMELIA-POWHATAN-
INCLUDING THE CITIES OF...LOUISA...FARMVILLE...GOOCHLAND...
ASHLAND...CREWE
954 PM EST SUN JAN 22 2012

...FREEZING RAIN ADVISORY REMAINS IN EFFECT UNTIL 6 AM EST
MONDAY...

A FREEZING RAIN ADVISORY REMAINS IN EFFECT UNTIL 6 AM EST MONDAY.

* AREAS AFFECTED: THE NORTHWEST VIRGINIA PIEDMONT.

* HAZARDS: AREAS OF FREEZING DRIZZLE AND FOG.

* ICE ACCUMULATIONS: A TRACE TO LESS THAN A TENTH OF AN INCH.

* TEMPERATURES: AROUND 32 DEGREES.

* TIMING: LATE THIS EVENING INTO VERY EARLY MONDAY MORNING.

* IMPACTS: A MINOR ICE ACCUMULATION IS EXPECTED MAINLY ON
ELEVATED SURFACES...WHICH COULD INCLUDE BRIDGES AND OVERPASSES
PRIMARILY ON SECONDARY ROADS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FREEZING RAIN ADVISORY MEANS THAT PERIODS OF FREEZING RAIN OR
FREEZING DRIZZLE WILL CAUSE TRAVEL DIFFICULTIES. BE PREPARED FOR
SLIPPERY ROADS. SLOW DOWN AND USE CAUTION WHILE DRIVING.

Monday: As mentioned, the freezing rain advisory will expire at 6 AM. The approaching frontal complex will be here later in the day on Monday, but winds will shift to the south as a warm front passes through Virginia and increase in speed, gusting up to 20 mph at times. This will help bring in some warmer (albeit still humid) air, allowing temperatures to climb out of the 30s around sunrise and into the mid 50s by Monday afternoon. The winds die down some Monday night, and lows get down into the mid 40s. Don’t be surprised to see some showers during the day, though I don’t think they will be either widespread or heavy. Keep the umbrella with you anyways.

Tuesday: The trailing cold front moves through late Monday/early Tuesday, but doesn’t do much to actually cool things off. Winds change in direction to the northwest, skies begin to clear, and temperatures make a run at 60 degrees. Winds on Tuesday will be breezy, but not overly so. Temperatures fall into the upper 30s Tuesday night.

Partly cloudy skies continue on Wednesday, though temperatures will run slightly cooler than Tuesday, but still into the 50s. Our next rain chance enters the picture on Thursday, and things still look a bit unsettled for the weekend.

January 23, 2012 12:57 AM 0