*Early Season Winter Storm On Tap Friday.*
Get your Cameras Ready!!! Send me your pics...BestWxMan1980@yahoo.com
SW Louisiana Forecast Discussion...This is a discussion that may look more like one you'd see up North this time of year, not South Louisiana.The players for the potential snow event are on the field. The burning question is will we get to play in the game? First, the easy part of the forecast...short-term.Today's forecast was right on track with brief sunshine into early this afternoon before the clouds returned right on schedule. After a cold start in the upper 30s to lower 40s, it was a cool afternoon with highs in the low to mid 50s. It will be overcast overnight as the potential winter storm gets its act together out West. It won't be terribly cold overnight, and it may not even seem like it's going to snow in less than 24 hours. Temperatures should be similar to last night with readings from the mid 30s to lower 40s. It will remain dry across the area overnight, but we'll be watching radar returns across West Texas.
Friday could be a magical day, and a day we never forget!!! When forecasting snow on the Gulf Coast, things can change at a moment's notice, and while my forecast confidence is high that it will SNOW, I reserve the right to change my mind at the last minute tomorrow depending on how this plays out. That being said, here is what I see. The short wave (upper level disturbance) embedded in the Jet Stream and current NW flow aloft at the surface is in transit tonight, and is situated over West Texas and Eastern New Mexico with areas of snow between Amarillo and Lubbock. This is part of the snow maker. The other part lies in the Gulf of Mexico. A surface low has begun to develop off the coast of South Texas East of Brownsville. This low will be moving ENE across the Gulf waters Friday and Friday night, and moisture will be surging Northward. Also, a surge of Arctic air from Canada behind another strong cold front is making its way towards the forecast area, and will be moving in Friday morning. All of these factors will congeal, and send moisture into the area over the top of the cold air at the surface. Additional lift and energy from the Subtropical Jet Stream will factor into this system as well. Snow will continue to develop and expand in areal coverage overnight and during the morning hours on Friday across Texas. As the short wave rounds the base of the digging trough, and the surface low advances closer to the forecast area, precipitation will begin mid-late morning Friday. IT should start as rain across the area, with a possible mix of snow even at the onset across Northern portions of the area where the colder air will be in place sooner. Temperatures will not warm up much at all before the rain begins with only lower 40s expected at best. As the rain commences, the temperature will begin falling back into the 30s, and continue falling until Saturday morning. As the temperatures fall back into the 35-37 range Friday afternoon, rain will begin to mix with snow around 3p.m. or so for the Lake Charles area. I will have a definitive precipitation time line shortly. The p-type should be all snow by the evening hours through overnight before ending early Saturday morning. Snow could be moderate to heavy at times across the forecast area, and snow should occur all the way to the coast, though it may stay mixed with rain a bit longer down there. The best chances of seeing accumulations will come after sunset Friday until the precipitation ends early Saturday. At this time, based on model output it looks like the heaviest amounts of snow will be along and north of the I-10 corridor with 1-2" possible around Lake Charles, and higher amounts of up to 3" possible North of the I-10 corridor. Up to an inch is possible along the coast. However, until the event actual begins pinning down actual accumulations will be near impossible. Some model guidance suggests 3-5" of snow across almost the entire forecast area, and as far back as Houston. I will play it conservative for now, and stick with 1-3" across the forecast area, but I would surmise that the 5" possibility could come to fruition somewhere in the forecast area. I will fine tune the forecast as the event begins on Friday. It is certain that the event will begin as rain. Here is the precipitation time line I promised you...This is for Lake Charles & Vicinity.
Cold Rain--- 10a.m. Temp 40
Rain/Snow Mix--- 2p.m. Temp- 37
All Snow--- 5p.m. Temp- 33
Snow Ends--- 3a.m. Saturday Temp- 30
The colder air will begin filtering into the region Friday morning, and as the rain begins to fall the air column will cool as some evaporative cooling takes place. Any accumulation of snow will be historic for the region, as this will be the earliest such occurrence of accumulating snow across the area. It would surpass the snowfall of 2008 by one week to establish a new record. It would also be historic in that accumulating snow has never occurred on back to back years in December. In 1948 and 1949 snow accumulated in back-to-back years at Lake Charles. This would also be only the 17th measurable snow in recorded history for the city of Lake Charles. That is, amounts of at least 0.01". Snow will accumulate on grassy and elevated surfaces first. This includes roofs, trees, cars, and bridges and overpasses. Yes, it is very promising and exciting for the prospects of snow, and it will a great time and fun night for all. I hope you enjoy it with your family and friends. It will be the perfect snow for making a snowman and throwing snow balls...just like last year!!! However, the reverse side of this is that travel problems and treacherous travel will be induced by the snowy conditions Friday night through early Saturday morning. As the temperatures fall to below freezing Friday night, any snow that has melted will re-freeze, and the continued snow fall will stick. This will likely initiate icy roads across much of the area. Bridges, overpasses, and other elevated roadways will be the first to ice up, and this could occur even with surface temperatures just above freezing. Later on, secondary roads and many city streets could develop icy spots especially if the snow lasts longer or is heavier than expected. The bottom line is, that travel is not recommended Friday night through early Saturday. Anything that falls and sticks will remain through about mid-morning Saturday when temperatures warm above freezing.
With the impinging early season, unprecedented winter storm the National Weather Service has issued the following watches/warnings/advisories.
*The Winter Storm Watch that was in effect for the entire forecast area has been discontinued.*
*A Winter Storm Warning is now effect North of the I-10 corridor in SE Texas and SW Louisiana. This includes Tyler, Jasper, Newton, and Hardin Counties in SE Texas, and Beauregard, Allen, Vernon, Rapides, Avoyelles, Evangeline, and St. Landry Parishes in SW Louisiana.* For SE Texas, the Winter Storm Warning is in effect beginning at Noon. While for SW Louisiana, the Winter Storm Warning is in effect from 6p.m. Friday to 9a.m. Saturday.
*A Winter Weather Advisory is in effect for the remainder of the forecast area from 6p.m. Friday until 9a.m. Saturday.* This includes Jefferson and Orange Counties in SE Texas, and Calcasieu, Cameron, Jefferson Davis, Acadia, Lafayette, Vermilion, St. Martin, Iberia, and St. Mary Parishes in SW Louisiana.
In the Winter Storm Warning area, accumulations of 2" or greater is expected, while 1-2" of snow is expected in the Winter Weather Advisory area. These advisories and warnings could be revised depending on how the event unfolds Friday. Travel is strongly discouraged Friday night as the roads become treacherous.
The first area wide freeze of the season will accompany this event. The Arctic air moving in will result in strong CAA during and after the snow, and temperatures by Saturday morning at sunrise will be in the 20s for almost everyone. The exception will be the immediate coast. Readings around 25 are expected near Alexandria and Fort Polk to around 28 for Lake Charles and Lafayette. Temperatures should bottom out in the 30-32 range along the coast. Wind will also be another issue on Friday and even more so Friday night into Saturday. A wind chill will be present throughout the day Friday. Winds will be out of the NNE during the day becoming Northerly overnight on the back side of the Gulf low. Wind speeds should be between 15-25 mph, to add insult to injury. Wind chill readings will drop throughout the day with morning readings in the 30-35 range, but by Friday night the wind chill should be in the 15-25 range, with a wind chill by early Saturday morning right around 15.
Forecasting snow is a very complex situation, and the slightest minute change in atmospheric conditions or moisture availability can change everything, and leave us with just a cold rain. Everything is in place for the snow, and I don't believe its a matter of will it be cold enough or will there be enough moisture. The atmospheric profile (air column) supports a rain/snow or all snow event. This is a rare set up for our part of the world. Often times, it is cold enough, but there's no moisture, or there's moisture but it's not cold enough. Other times, we have a set up that favors a sleet or freezing rain event as opposed to snow. I won't be specific about that set up here because that is not expected, but just to cite a prime example look no further than the Ice Storm of 1997. Just as I did last night, let's take a look at some model output for the window of opportunity for our snow...focusing on the GFS and NAM once again.
This is the GFS at 6p.m. CST Friday.
You can see it shows all snow across the area with the magical 540 line at 850 mb. along the coast up towards Woodville, MS to near Meridian, MS and Tuscaloosa, AL. Precipitation covers nearly all of Louisiana with an area of heavier precipitation from extreme SW Louisiana back through the Houston area. Rain will still be occurring at this time across SE Louisiana, as the coldest air will not have arrived there yet, but looks like ahead 6 more hours.
The GFS at Midnight CST Saturday.
Snow is occurring almost all of Louisiana with rain/snow mix for New Orleans and areas South of Lake Pontchartrain. The back edge of the snow is near Houston on this run. There are still minor timing differences concerning the start and end of the precipitation. As you will see on the NAM below for the same time frames...6p.m. and Midnight CST Friday-Saturday, it is very similar with the placement of the 540 line and the areas of snow.
The NAM at 6p.m. CST Friday:
The heavier snow is lined along the SE Texas Coastal Plain into extreme SW Louisiana. The 540 line runs near Victoria, TX to Lake Charles to Woodville, MS and into Northern Alabama.
The NAM at Midnight CST Saturday:
At midnight on the NAM, significant snow is occurring across the entire forecast area. The back edge of the snow is near Houston, very similar to its GFS counterpart. It is a rain/snow mix for SE Louisiana on this run as well. The 540 line runs from Vermilion Bay to Hammond to Montgomery, AL. The one thing we don't know with forecast models is what does it look like in between the times shown? The models run 4 times a day, and each one goes out to a different time frame. The NAM goes from 0 hrs. to 84 hrs. (3.5 days). While the GFS goes from 0 hrs. to 384 hrs. (16 days). It runs in 6, 12, and 24 hr. increments. Therefore, anything between 0z and 6z is not shown by these models.
Each model run will vary a bit, but we're less than 24 hours out from the event now, and more often than not models don't waver too much in the short range. There will continue to be questions about accumulations until the event comes to fruition, but the forecast confidence is high that it will snow. With the consistent model runs such Monday, the models have gained more credibility. I am humble enough to admit that forecasting snow is a difficult task anywhere, but especially along the Gulf coast, and to say that we won't know exactly what's going to happen until we can just look out the window and see it, and stop depending on radar downstream.
Get your cameras ready! I want to see your snow pictures. I hope to take plenty of them myself whether I am here at home or out snow chasing. Send your pictures to me via e-mail. BestWxMan1980@yahoo.com. I will post them here on the blog this weekend, and of course give you proper accolades. Now onto the rest of the forecast discussion...
The weekend...As stated above, any snow that falls and accumulates Friday/Friday night will remain in place through mid-morning Saturday as temperatures will be very cold to start the day Saturday. Skies will quickly clear out behind the snow. Morning temperatures will definitely be in the 20s, but it is the afternoon temperatures that could be a challenge depending on how much snow cover, if any, there is to start the day. Snow cover would keep temperatures colder than forecast, and models don't pick up on this very well. I will undercut guidance for this reason, and keep highs in the low to mid 40s for now. It'll be cold either way to say the least for Saturday. The winds will gradually diminish during the day as the low pressure pulls further away. Wind chill readings will be around 15-20 in the morning as stated earlier, and in the 30s in the afternoon. All snow should melt by noon Saturday if not sooner. Along with the current Winter Advisories in place across the area, I expect that a Freeze Warning will be issued as well since Saturday morning will be the first freeze of the season across the forecast area. Clear skies will prevail for Saturday, but some clouds could return for the Saturday night period as the ever progressive weather pattern continues. It will be another cold night Saturday night, but not near as cold, and an area wide freeze is not expected, though the coldest locations could see freezing temps again. Mid 30s seem logical for the rest of us. Air mass modification begins on Sunday as another system in the everlasting parade moves into view. A chance of showers returns to the forecast as another Gulf low, albeit much weaker, develops. This will bring a chance of rain with cool temperatures in place. Highs should eclipse the 50 degree mark and top out in the mid 50s. Showers will most likely occur in the afternoon and overnight hours Sunday.
Chances of rain remain in place for the start of the new work week with the Gulf low passing by. Such timing of when the rain will commence and vacate the region is marred by some uncertainty at this point with the progressive El Nino pattern in place. A break looks to occur at some point Monday, but when exactly that will be shall be determined in a later forecast. No doubt air mass modification will continue as the overall flow becomes zonal temporarily. A digging trough and associated cold front will be approaching for Tuesday, and another chance of rain is inserted at this time. Mild weather is expected ahead of the front with daytime highs in the 60s and lows modifying into the 50s. A return to colder weather comes right back on Wednesday behind the latest front on Tuesday. It could have some Arctic connections, but again I will broad brush that for now. Wednesday could be a day of overrunning as the front hangs up for a bit along the coast before getting the added boost it needs with another NW flow embedded short wave. Cool and cloudy should suffice for Wednesday with a chance of showers. Strong high pressure from Canada builds in by Thursday, and it will be quite chilly as some modified Arctic air builds in. Another freeze could occur toward the end of next week, but without precipitation.
Stay tuned for more on Friday's Winter Storm.
Preliminary Numbers & Zone Forecast:
LCH 39/42 28/43 34/55 0 80 90 20 0 40
LFT 38/44 28/42 33/54 0 80 90 20 0 40
BPT 39/47 27/44 35/56 0 90 80 20 0 40
AEX 36/44 24/40 30/51 0 80 90 30 0 40
POE 37/43 25/41 30/52 0 90 80 20 0 40
ARA 40/46 29/44 34/54 0 80 90 20 0 40
*Winter Storm Warning in effect North of I-10 from 6p.m. Friday to 9a.m. Saturday.*
*Winter Weather Advisory in effect along and South of I-10 from 6p.m. Friday to 9a.m. Saturday.*
Tonight...Cloudy and Cold. Low 39. North wind 10-15 mph.
Friday...Cloudy, Windy, and Cold with Rain likely in the morning, becoming Rain and Snow Mix in the afternoon, before changing to all Snow during the evening. Snow accumulations up to 1". High 42. Temperatures falling into the mid 30s in the afternoon. North wind 10-20 mph and gusty. Wind chills in the 20s. Chance of precipitation 80%.
Friday Night...Snow Likely. Up to 2" of accumulation possible. Ice developing on roadways overnight. Snow ending after midnight. Very Cold with a Freeze. Windy. Low 28. North wind 15-20 mph and gusty. Wind chill 15-20. Chance of snow 90%.
Saturday...Becoming Sunny with a few lingering flurries early. Icy roadways until about mid-morning. Continued Cold. High 43. NE wind 10-15 mph. Wind chill 15-30.
Saturday Night...Clear early, but becoming Partly Cloudy overnight. Not as Cold. Low 34. East wind 10 mph.
Sunday...Partly to Mostly Cloudy with a 40% chance of showers in the afternoon.Warmer. High 55. SE wind 10 mph.
Drew's 7 Day Outlook for Lake Charles & Vicinity
Friday
12-4-09
Low: 39
High: 42
Falling to 33 by 5p.m.
Precip: 80%...90% Night
Wind: N 15-20
W.C.: 20-30
Saturday
12-5-09
Low: 28
High: 43
Precip: 20%
Icy Roads until Mid-Morning
Wind: NE 10-15
W.C.: 15-25
Sunday
12-6-09
Low: 34
High: 55
Precip: 40%
Wind: SE 10
Monday
12-7-09
Low: 46
High: 65
Precip: 50%
Wind: SSE 10-15
Tuesday
12-8-09
Low: 50
High: 68
Precip: 60%
Wind: SSE 15-20
Wednesday
12-9-09
Low: 48
High: 55
Precip: 60%
Wind: NNW 10-15
Thursday
12-10-09
Low: 32
High: 53
Precip: 0%
Wind: NNW 10-15
...Marine Forecast...
*Small Craft Advisory.*
Tonight...North winds 10 to 15 knots becoming northeast 15 to 20 knots after midnight. Seas building 3 to 5 feet after midnight.
Friday...North winds 20 to 25 knots. Seas 4 to 7 feet. A chance of rain in the morning...then rain likely in the afternoon.
Friday Night...North winds 20 to 25 knots. Seas 4 to 7 feet. Snow and rain in the evening...then a chance of rain and snow after midnight.
Saturday...North winds 20 knots becoming northeast 10 to 15 knots in the afternoon. Seas 4 to 6 feet subsiding to 2 to 3 feet in the afternoon.
Saturday Night...East winds 10 to 15 knots. Seas 1 to 3 feet.
Sunday...Southwest winds 15 to 20 knots. Seas 2 to 4 feet. A chance of showers.
I will end things here for tonight. The blog will return to normal over the weekend. Stay tuned for all the latest developments on Friday's winter storm.
Good night and God bless!
-DM-
