Tuesday, February 26, 2008

What's ahead going into March...

The next few days will be on the cool side, with afternon temperatures mainly in the 40s. Our next cold front will slide through by Saturday morning, but won't have much of an impact on the area. There may be a few passing showers, but the weekend should be mainly dry. Temperatures will be in the seasonable low to mid 50s.

Briefly warmer early next week...

It looks like we'll get a good shot of warmer air in here early next week, with temperatures Monday and Tuesday well into the 60s (maybe touching 70). The next system to watch will affect us Tuesday and Wednesday (March 4-5) with rain. It doesn't appear the next shot of cold will be all that strong...until the next system passes by (March 7). A upper trough over the Central U.S. will finally lift out to the northeast at that time.

And beyond...

As the trough lifts out, some of the cold building over Canada will sink southeast into our region, so look for the weekend of March 8-9 to be chilly. After that, the longer range data favors a trough digging out west, leading to a warm-up here in the East the week of March 10th.

Friday, February 22, 2008

Early Friday morning update...

The model data has been right on with the rapid warming aloft. This means most of the precipitation will be in the liquid form over our area. The only issue for the morning commute will be the temperature and the continued threat of freezing rain. I'm not sure this will be a significant on roads in the metro as the temp will be in the low 30s but increasing traffic and the increasing sun angle (yes, as I mentioned earlier this has an impact even when the sun is not out) should keep icy spots at a minimum. However, beware during the morning commute on bridges and elevated surfaces, which are the first to freeze. Areas north and west will have a more significant risk of icing, and I'm talking mainly western Goochland up through NW Hanover and Caroline and points north and west. This area could see freezing rain linger through the morning hours. There could be up to 1/4 inch of ice accumulation on trees and power lines, so that could certainly cause some problems.

Temps should be rising above freezing by about 9 A.M. in the metro, so just periods of light rain are likely throughout the day. In terms of amounts, the data favors about .25", maybe a little more in some locations. Here's my updated breakdown of what to expect in your neighborhood:

METRO RICHMOND/TRI-CITIES/FARMVILLE/NORTHERN NECK: Freezing rain early on should change to rain around 8 A.M. or 9 A.M. Icy spots will be at a minimum, mainly bridges, elevated surfaces and secondary roads. Be careful on decks and walkways. Some icing on trees and power lines (up to 1/10")

GOOCHLAND/HANOVER/CAROLINE: Freezing rain should change to rain by around 10 A.M. Some icy roads for the AM commute and 1/10" to 2/10" icing possible on trees and power lines.

CHARLOTTESVILLE NORTHEAST TO FREDERICKSBURG: Freezing rain and sleet for the AM commute...freezing rain will continue to be an issue through midday, with temperatures gradually rising just above 32 degrees during the afternoon. Icy roads possible for the AM commute, although major highways should be OK (except bridges and elevated surfaces). Ice accumulation up to 1/4" possible on trees and power lines.

Thursday, February 21, 2008

Update on tonight's event...

The low level cold air in place is a little stronger than indicated by the models. That means our threat for winter weather tonight is still on track. The data is trending toward more liquid, but it is likely scouring out the cold air too quickly. That being said, there are a few issues to deal with...extremely dry air in place now...an onshore flow that will quickly import milder air, especially aloft...and the lack of significant QPF (precipitation amounts) on the latest model runs.

While the model analysis might try to convince us to change the forecast, I don't think that's the smart move right now. Despite the very dry air in place now, the onshore flow should help to moisten up the lower layers of the atmosphere this evening. I still expect some snow and sleet to develop very late tonight (after midnight). This will likely mix with freezing rain rather quickly, by the morning commute. The key to potential problems is how long the temperature remains at or below freezing. In the metro area, I think the transition to rain will probably happen during the morning commute. Keep in mind, the expected precipitation amounts are expected to be light. With that in mind, there will still be slick spots though, especially on bridges and overpasses. By 9 A.M., we should be just wet...the increasing sun angle (yes, this has an impact even when the sun is not out!) should help to alleviate any further icy problems in the metro. However, north and west of Richmond...in the climatologically favored areas, the colder air will be much harder to dislodge. This region, from western Goochland west to Charlottesville and then northeast to Fredericksburg (including northwest Hanover and Caroline) will likely see a longer period of sleet and freezing rain. So icy problems will continue there well into the morning. By afternoon, everyone should be dealing with periods of mainly light rain.

Here are my thoughts for your neighborhood:

METRO RICHMOND: Snow/sleet develops after midnight, mixes with and changes to freezing rain by around 4 A.M. A light mix of icy precip than changes to rain during the morning commute (8 A.M.-9 A.M.)...accumulation should be light and many icy/slick spots

TRI-CITIES/FARMVILLE: A light mix of snow/sleet/freezing rain develops late tonight (probably after midnight) and changes to just freezing rain for a period of a couple of hours. The changeover to rain should happen by 8 A.M. (some slick spots for the commute)

CHARLOTTSVILLE TO FREDERICKSBURG: A mix of snow and sleet develops late tonight...changes to a mix of sleet and freezing rain by the morning commute...freezing rain could linger through the morning...accumulation of 1-2 inches of snow and sleet possible

NORTHERN NECK: A light mix of snow and sleet develops well after midnight (3 A.M. or so)...mixes with freezing rain and then changes to rain during the commute...accumulation should be light with mainly icy spots on secondary roads

A wintry mix Thursday night...

The model data is showing good consensus for a mixed bag of snow, sleet and freezing rain to occur late Thursday night, probably arriving shortly after midnight. This will be caused by warmer air running up and over cold air at the surface. The milder air will eventually bring a change to rain, but probably not before the morning commute in the metro and certainly later Friday morning in areas north and west of Richmond. Stay tuned for more details in an afternoon update.

Looking ahead...

Temperatures will bounce back above average by early next week...and maybe even over the weekend. Another shot of colder air is still scheduled to arrive later next week (Feb. 27th and beyond). This cold air will probably linger through the first few days of March. The longer range data suggests another storm impacting the area March 5/6, with the possibility of some winter weather on the backside of this system. It's quite a ways out, but something to keep an eye on. The general target dates for storms in the longer range have been pretty good lately.

Monday, February 11, 2008

The wind and chill ease...some rain on the way

Wow, what a wind out there yesterday! Gusts over 50 mph were common...here are some of the highest gusts reported from across the region:

Richmond Heights--63 mph
Charlottesville--55 mph
Newport News--52 mph
Gwynn (Mathews Co.)--52 mph
Petersburg--49 mph
Hanover--48 mph
Farmville--47 mph
Staunton--46 mph
Fredericksburg--46 mph
Norfolk--46 mph
Bowling Green--45 mph
Wakefield--38 mph

If you thought it was bad here, try combining the high winds with snow squalls. A friend of mine told me about what ended up being a 36-car chain reaction crash in Rochester, NY on Interstate 390. The visibility was extremely low due to blinding snow and whiteouts.

Our weather has quieted down and the chill will ease over the next 24 hours. Moisture will be on the increase though, and a few showers are possible by Tuesday evening. A storm will cross the Mid-Atlantic on Wednesday, leading to more rain.

A very mild finish to the week expected...

Behind the storm, I think we're in for a very mild Friday, with afternoon temperatures likely jumping above 60 degrees. Then a cold front will sneak through the area to cool us off for the weekend, with another storm due to bring rain on Sunday.

The longer range...

A few other dates to watch will be...on the 21st/22nd, the model data is still showing a storm impacting the area. The solutions are a bit warmer, so it looks like rain...with a cold shot following. That cold shot may be brief, but another blast seems to be on tap to finish the month...arriving on or about the 27th.

Friday, February 8, 2008

Mild start to the weekend...

We're in for a very mild start to the weekend...not record territory like earlier this week, but temperatures will likely reach the low 60s Saturday afternoon. Then a push of cold air will arrive in the Mid-Atlantic on Sunday. The front ushering in the chill will arrive during the day, with strong, gusty west winds. The core of the cold will settle over our area Sunday evening and stay through Monday.

Moderation for mid-week...

The cold won't last too long, as moderation is likely Tuesday and Wednesday, with readings back in the 50s. The next storm will bring some rain late Tuesday night and Wednesday. In its wake, temeperatures will probably still be a few degrees above average.

The longer term...

A few other dates to watch here...first the 15th/16th for a storm developing off the East Coast. At this point, it looks like the storm will be too far off the coast to have any significant impact here. However, it will help to usher in another cold air mass from the north. The next dates to watch will be the 21st and 22nd (Thursday/Friday), with a potential coastal storm showing up on the long range data. The big question is, how much of the cold air will hang around? Will there be a threat of winter weather? It's a little to early to speculate and my hunch is no, but we'll keep an eye on it.

Wednesday, February 6, 2008

Severe weather this evening?

With the record-breaking warmth and severe storms over the Ohio and Tennessee Valleys, there has been quite a bit of talk about the potential of severe weather here in Virginia this afternoon and evening, as a cold front approaches the region. The extreme heating has brought some instability, but it's not all that impressive. Low level wind shear is increasing, and certainly a few storms may develop. I'm sure you've noticed the wind gusts we've had out there today. Very strong winds just above the surface may get dragged down in any developing storms this evening, so the main severe threat would be wind.

The technical numbers...

We use several indices to determine severe weather potential. I'll touch on a few of these here, as forecasted by the model data. The lifted index goes negative this evening, but it's not all that low...indicating a lack of significant instability. The SWEAT index flies up over 400. It does this very rapidly by about 7 P.M. and a number like this often indicates a strong risk of severe weather and even tornadoes. While this is highly unusual for February around here, this is a very unusual weather situation for this time of the year. The Showalter Index is another stability index and isn't all that impressive for Richmond this afternoon. The overall numbers are a bit more impressive to the north, and the severe weather threat may indeed be higher for DC over to Eastern Maryland during the evening.

So what to expect?

We'll see a round of showers move across the region this evening with embedded thunderstorms. I don't expect an outbreak of severe weather, but a few storms may contain some very strong wind gusts.

Tuesday, February 5, 2008

Record warmth!

We tied the record high at RIC airport today, reaching 76 degrees. This record was originally set in 1991. If you like the spring-like air, it will stay around for at least another 24 hours. I expect us to shatter the record high of 71 tomorrow, which was set in 1938. Gusty southwest breezes, some early sunshine and morning temperatures near 60 degrees should set the stage for a very warm day. A cold front will offer some showers and thunderstorms later in the day into the night. Some of the storms potentially could be strong, depending on the timing of the front.

Today is National Weatherman's Day!

Did you know there was such a day? It's time to be grateful for the services we meteorologists provide! Forecasting certainly is a challenging business and probably will always be an inexact science as Mother Nature does whatever she wants. National Weatherman's Day commemorates the birth of John Jeffries, one of America's first weathermen. He was born on February 5th, 1744.

What's coming up...

As I have alluded to over the last week and a half, we expect a good surge of cold air to arrive later this upcoming weekend. It will be brief though, with the chilly air around Sunday and Monday. Moderation will occur by the middle of the week. Looking at the longer range model data, a few dates to watch will be the 13th/14th for some rain, and then the 18th and 19th (again probably some rain) with another good surge of cold air arriving that week (by the 20th). It's possible later that week if the forecast pattern works out that some winter weather could be on the way by the 21st/22nd...but that's a long ways off!

Monday, February 4, 2008

Possible record warmth this week...

February has gotten off to a mild start and believe it or not, it's about to get much warmer. I expect temperatures in the 70s both Tuesday and Wednesday, which could knock off a couple of records. The record highs at RIC Airport are 76 degrees on Tuesday (set in 1991) and 71 degrees on Wednesday (set in 1938). Nighttime temperatures Tuesday night may not get much lower than 60 degrees. A cold front will bring about a change later in the week, offering some showers on Wednesday and cooler air for the region thursday and Friday. We've been watching for the return of colder air from Canada, but that may now be delayed. More on this in a new post later Monday...