SW Louisiana Forecast Discussion...The changes ahead of the major Arctic outbreak occurred right on schedule today. After a morning freeze across the area, clouds increased during the day with the entire area enveloped in overcast conditions by mid-afternoon. Temperatures moderated as well as the previous Polar high shifted Eastward into Dixie. This allowed for an Easterly fetch this afternoon which thwarted CAA and transitioned the area to a WAA regime. After the morning freeze with temperatures between 25 and 30, afternoon highs were warmer than the previous days with some 50s noted across the area, but much of the area remained in the 40s. It has been dry thus far across the forecast area, but there are several factors coming together tonight to produce the first rainfall of the new year. As the high drifted further East this afternoon and evening winds have became SE across the majority of the area, and in areas where they haven't done so just yet, they will overnight. All of this is ahead of the major Arctic blast which will arrive Thursday morning.
A surface low and trailing warm front has formed across South Texas and into the Gulf waters and is lifting NE tonight. This combined with Subtropical Jet Stream Energy and embedded short waves is resulting in increasing isentropic ascent (overrunning) across the forecast area. As the warm front and associated surface low lifts NE and attracts more Gulf moisture, a theta-E ridge (tongue of warm, moist air) will move out in advance of it. The overcast conditions will remain overnight as you would expect, and as the isentropic lift continues to intensify rain will become likely overnight. Most of the rain should be light to moderate at times, and a heavy rainfall event is not expected, nor is any severe weather. Instability is very sparse across the forecast area, and it is essentially the presence of a lifting mechanism that will lead to the development of the rain across the area. The warm front and associated surface low will continue making good progress to the NE overnight, and track across the forecast area in the early morning hours. The leading edge of the Arctic air mass is denoted by the potent cold front, which as of 6Z Thursday (Midnight CST Thursday), was in the vicinity of Dallas-Fort Worth, and was screaming SE at around 30-35 mph. The air mass has modified immensely across the forecast area with most locations in the 40s as of this writing. On a typical night, the temperatures slowly fall, but tonight will be an exception. The WAA regime ahead of the Arctic blast will result in temperatures holding near steady or only changing a few degrees one way or the other. They may drop initially as rain begins to fall due to some evaporative cooling and moistening up of the boundary layer that always occurs in this situation, but then as the front approaches and the WAA regime intensifies, temperatures will rise a few degrees until frontal passage. Readings should hover between 45 and 50 for the early morning hours.
The front, currently near Dallas as I've stated, will be in the forecast area before sunrise on its current pace. The ETA of arrival for the cold front into the Lake Charles area should be between 12 and 14Z Thursday (6-8 a.m.). This air mass behind this front is of true Arctic nature, and we'll be getting more than just an average glancing blow this time. Part of the reason for this is because of a majority of the contiguous 48 states being covered in snow at this time. Snow is the ground into the Ozarks of Oklahoma and Arkansas. This won't allow for much modification of the air mass, as you would typically expect from an Arctic air mass heading for the Gulf coast. The temperatures in the source region have been in the -30s and -40s this week, and this is the air that is spilling into the country tonight. When we last spoke last night, the Arctic front had just had its passport checked and cleared customs at the Canadian border as was pushing into Montana. Here we are about 24 hours later and the front is in the DFW Metroplex. To give you an idea of how powerful this front is...it's 64 in Brownsville, TX, but in Amarillo, TX it's 16 at this hour. Wind chills in the Panhandle have dropped to below 0. This is the biggest Arctic outbreak that will affect our region in 14 years...February 1996 was the last time!
Thursday morning will dawn on the mild side for much of the area. The front may have already cleared NW portions of the forecast area by sunrise, but most of us will still be in the relatively warm spectrum of things. Off and on rain will be occurring as the overrunning continues ahead of the front. Rainfall amounts should generally be 1/2" or less. Temperatures may reach the upper 40s to lower 50s ahead of the boundary, but not much rise is expected before the door to the Arctic is open wide. Once the front pushes on through, temperatures will drop off the table. Falling temperatures are expected for the rest of the day in the wake of the front, and we'll be near freezing by 4-5 p.m. The rainfall will come to an end in the afternoon as overrunning comes to an end with drier air punching in. There will be some post-frontal rains as the overrunning continues for awhile until the drier air reaches the mid and upper levels ending the rain. Rain will be the predominant precip type across the entire area, however, there is still a window of opportunity for the rain to change over to snow across much of the area (mainly north of I-10) before all precipitation ends by late afternoon. The best chance to see some snow will between noon and 4p.m. It is a small window, and certainly no accumulations are expected anywhere in the forecast area. It will just be a pretty sight to behold if indeed it does occur. The extremely cold air will be the story. A very tight pressure gradient will be present behind the Arctic front, and winds will shift from SE to NW and increase to over 30 mph at times Thursday afternoon. This will make for a very blustery day. Wind chills will come into play after lunch, and continue to become more of a problem as the day wears on. By evening, we'll feel like we're living in the Great Plains or Mid West somewhere as wind chills drop into the 10s. Skies will clear late afternoon as the Arctic high slides down the front range of the Rockies ushering in the drier air at all levels.Temperatures will reach the freezing mark Thursday evening, and then it becomes a struggle to get back to freezing well into the weekend.
The forecast for Thursday night through the weekend is very cold! Beginning Thursday night record cold is expected as the coldest air mass in 14 years effects the region. Clear skies and continued strong CAA with gusty North winds Thursday night will make for a very brutal night and a frigid Friday. Temperatures will continue the downward spiral Thursday night reaching eventual lows in the mid 10s to lower 20s across the forecast area. Even the coastal waters will experience hard freeze conditions. Winds will continue out of the NNW over 20 mph at times, and this will create dangerous wind chills in the single digits into Friday morning. Friday will be very cold, and I believe it is looking more and more likely that we won't get above freezing. An active Subtropical Jet Stream will likely stream some cloud cover over the area. With such a cold air mass in place, we'll already be struggling to warm even with full sunshine, however, the clouds will just help thwart any attempt at a warm up. Parts of the area may not even reach 30 degrees, and yes that's the actual temp I'm talking about. Wind chills will remain in the likely Wind Chill Advisory criteria with readings in the single digits to around 15. Friday should remain precipitation free, but there is a slight possibility of a few snow flurries if there is enough moisture available via the Subtropical Jet. The clouds should thin out by Friday night as the Subtropical Jet is suppressed over the Gulf. The Arctic high will continue dropping to the SE as the Polar Vortex will be centered over the Great Lakes. The pressures will reach ear-popping levels, and the temperatures will reach teeth-chattering levels. Teens are expected nearly area wide Friday night into Saturday the exception being the coastal areas where 20s are expected. Winds will have calmed down some, but it won't be dead calm just yet. The wind chill readings will be in the single digits once again. I expect mid 10s down to the I-10 corridor for Saturday morning lows while lower 10s seem likely up towards Alexandria. Record lows are expected both Friday and Saturday mornings.
It's going to be a cold weekend for the 2nd weekend of 2010. Saturday will once again be a day where the temperature struggles to make the freezing mark. The Arctic high pressure will be supplanted over the region, and lots of sunshine is expected, however you will likely want to spend this weekend hibernating! Winds will continue to diminish Saturday as the CAA weakens with the high edging closer to the area. The prolonged freeze will continue. There is still some speculation as to whether Saturday or Sunday morning will be the coldest morning across the forecast area. A lot of this hinges on the orientation of the high at that time. I am hinging on Sunday morning being the coldest morning at this point due to nearly calm winds and clear skies Saturday night with the strong Arctic high nearly overhead. Records may not be threatened on Sunday morning as these values are in the low to mid 10s across the area, but it will be close. Mid 10s are likely for most locations with the coldest locations across the forecast area possibly getting as cold as 10. After another near record cold start to the day Sunday, some modification is expected Sunday afternoon with highs finally getting above freezing barely. The high will remain very close by throughout the day. The entire weekend should be clear, though there is still some hint of a short wave moving across underneath the frigid air mass on Saturday. If this occurs, some snow flurries are possible. However, moisture will be very limited due to the cold air mass in place, so it may produce nothing more than clouds. Stay tuned!
Another very cold night/morning is in store for the Sunday night/Monday morning period. The incredibly cold air mass will finally begin its modification as the orientation of the high shifts to our NE. Skies should be clear, and winds will be light. Expect lows from around 20 to 25 with an apparent temperature near the same value. Monday will be another dry day, but air mass modification will continue only slowly. Arctic air masses don't modify as rapidly as a typical cold air mass does, and models don't pick up on this. Therefore, I am undercutting guidance for Monday and forecasting highs in the low to mid 40s. Clouds will increase during the day as our next weather maker gets its act together. Gulf air will move back into the area by Monday night, enough so that a chance of cold rain will be introduced after midnight. Temperatures should be above freezing all areas but 30s are expected for all except the coast. As another cold front approaches the area by Tuesday, rain chances will increase in response to forcing and some isentropic lift. There is the possibility of a Gulf low at this time, and this overspread rain across the area. While temperatures will no longer be bitterly cold at that time, it will still be below normal with highs only in the lower 50 at best. The cold front moves through late Tuesday into Wednesday, and this is when the highest chance of rain will occur. Colder air will infiltrate the region once again Wednesday as another shot of Arctic air looms, but it won't be as cold as the upcoming air mass. An overrunning situation sets up behind the front keeping in a chance for cold rain at the end of the forecast period. Highs cool back down into the 40s while morning lows stay above freezing. Beyond the forecast period, the isentropic ascent will remain in place for the rest of the work week as models hint at possible Gulf cyclogenesis with the cold air in place at the surface. This will keep things wet and cold. Stay tuned and stay warm!!!
Here once again are the record lows, expected lows, record low maximums, and expected highs for the Friday-Sunday period for your perusal.
Friday January 8
Record Low: 21- 1996 Projected Low: 18
Record Low Maximum: 35- 1968 Projected High: 31
Saturday January 9
Record Low: 22- 1962 Projected Low: 17
Record Low Maximum: 38- 1973 Projected High: 32
Sunday January 10
Record Low: 15- 1962 Projected Low: 16
Record Low Maximum: 24- 1962 Projected High: 37
Stay tuned for more on this cold outbreak!
Preliminary Numbers & Zone Forecast:
LCH 53/28 18/31 17/32 60 70 0 0 0 0
LFT 52/29 19/32 16/31 60 70 0 0 0 0
BPT 55/27 18/30 18/32 60 70 0 0 0 0
AEX 48/25 16/29 13/28 60 70 0 0 0 0
POE 48/26 17/29 14/29 60 70 0 0 0 0
ARA 54/30 20/32 18/31 60 70 0 0 0 0
*Hard Freeze Watch in effect Thursday Evening through Saturday Morning.*
Tonight...Cloudy and Warmer with rain becoming likely. Temperatures holding steady in the mid 40s or slightly rising overnight. SSE wind 10-15 mph. Chance of rain 60%.
Thursday...Cloudy with rain likely in the morning. Turning Windy and Very Cold before noon. Rain possibly mixing with snow and sleet from around noon until 4p.m. before ending. No snow or sleet accumulation. Skies clearing late. High around 53 early in the morning before falling into the lower 30s by evening. SSE wind 10-15 mph early, becoming NNW at 20-25 mph with gusts over 30 mph at times by mid-morning. Chance of precipitation 70%. Wind chills in the 10s in the afternoon.
Thursday Night...Clear, Windy, and Very Cold. Record Lows. Low 18. NNW wind 20-25 mph and gusty. Wind chills 0-5 degrees.
Friday...Mostly Sunny early, becoming Partly Cloudy and Very Cold. High 31. NNW wind 15-20 mph and gusty. Wind chill 5-15.
Friday Night...Clear and Very Cold. Record Lows. Low 17. North wind 10 mph. Wind chill 5-15.
Saturday...Sunny and Very Cold. High 32. North wind 5-10 mph. Wind chills 15-25.
Drew's 7 Day Outlook for Lake Charles & Vicinity
Thursday
1-7-10
Low: 53
High: 28
Precip: 70% Rain AM/Rain/Snow Mix PM...Before Ending
Wind: SSE/NNW 10-30
W.C.: 10s PM
Friday
1-8-10
Low: 18
High: 31
Precip: 10%
Wind: NNW 15-20
W.C.: 5-15
Saturday
1-9-10
Low: 17
High: 32
Precip: 0%
Wind: N 5-10
W.C.: 15-25
Sunday
1-10-10
Low: 16
High: 37
Precip: 0%
Wind: NE 5-10
W.C.: 10-25
Monday
1-11-10
Low: 24
High: 45
Precip: 0%
Wind: E 10-15
W.C.: 15-30
Tuesday
1-12-10
Low: 35
High: 51
Precip: 40%
Wind: SSE 10-15
W.C.: 25-35
Wednesday
1-13-10
Low: 38
High: 44
Precip: 60%
Wind: NNE 15-20
W.C.: 20-25
...Marine Forecast...
*Gale Watch in Effect.*
Thursday...West winds 15 to 20 knots becoming north 15 to 25 knots in the afternoon. Seas 3 to 5 feet building to 4 to 6 feet in the afternoon. Rain likely in the morning...then a chance of rain in the afternoon.
Thursday Night...North winds 20 to 25 knots. Seas 4 to 6 feet. A slight chance of rain in the evening.
Friday...North winds 15 to 25 knots becoming 15 to 20 knots in the afternoon. Seas 3 to 5 feet subsiding to 3 to 4 feet in the afternoon.
Friday Night...North winds 15 to 20 knots. Seas 2 to 4 feet subsiding to 2 to 3 feet after midnight.
Saturday...North winds 15 to 20 knots. Seas 2 to 3 feet.
Good night and God bless!
-DM-
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