*Significant Winter Storm Will Affect the Forecast Area Tonight. Precipitation Type Will Vary Depending Upon Your Location.*
SW Louisiana Forecast Discussion...Yuck! That's likely how anyone would describe today's weather. Rain, mostly light has been falling all day and into tonight and has been mixed with sleet periodically throughout the day. This has occurred even as far south as New Orleans. Some snowflakes have also been reported in portions of the area. Temperatures hovered around 40 all day, and it was windy as well to add insult to injury. Wind chills have been, and are still in the 20s. The surface low has developed and it moving NE paralleling the NW Gulf, and the cold core cut off upper level low is traversing the Big Bend region of Texas tonight. It will continue moving Eastward, and move into Louisiana Friday morning. Precip will continue until this ULL moves to our East. The precip is a given with chances maxed out overnight through early Friday. The complexity of the situation involves what type of precipitation as I've made mention of all week.
Rain will be the predominant and perhaps only p-type along and south of the I-10 corridor. Although, I still believe that as the ULL moves into close proximity of the area Friday morning that the dynamic cooling associated with this feature will transport some colder air downward to the surface as the precip continues to fall. This should be enough to allow for a changeover from rain to a mix of sleet/snow and perhaps ending as all snow. This would occur after 3a.m. and last until about 10a.m. Friday. Rain mixed with sleet will occur until that time. No accumulation of sleet is expected as temperatures remain above freezing in the mid 30s. There will be a small window of opportunity for some minor accumulations on grassy and elevated surfaces especially if the snow (if it occurs at all) falls heavily. The more significant winter weather threat will remain North of I-10. Sleet and snow will be the predominant p-type from Jasper and Newton Counties in SE Texas and for Beauregard, Allen, Evangeline, and St. Landry Parishes in SW Louisiana. Accumulations will be minimal at first due to the mixed nature of the precip and still some rain from time to time, however, after midnight accumulations between 1-2" are expected in this area as a transition to all snow should occur with the colder air moving into the region. Some icy roads will develop especially north of Hwy. 190. Further North, from Toledo Bend Country to Vernon, Rapides, and Avoyelles Parishes snow and sleet are occurring now, but in many of these areas, i.e. Alexandria, precipitation has been all snow for a few hours now. Accumulations are occurring around Alexandria over towards Marksville with some icy roads from sleet between Alexandria and Leesville. Significant accumulations of snow will occur in this area. Some locations could see as much as 4-6" of snow overnight as the snow will continue through the pre-dawn hours into mid-morning Friday. It is snowing all the way back towards Dallas and Waco. Dallas has had a record day today with over 8" of snow in many places. The entire Northern half of Louisiana is covered in snow tonight with amounts of 2-4" already from Shreveport to Monroe. The band of heavier snow will set up in the deformation zone, which I've discussed in the previous 2 blog entries. Based on analysis, this deformation zone should be somewhere in the NE portion of the forecast area, across SW Mississippi, and into the Northern Florida Parishes. This will be a major winter storm for the South with accumulating snow expected all the way down to Mobile, AL and Pensacola, FL on Friday. Snow accumulations could exceed 2" in some places from Baton Rouge to Slidell, and even New Orleans could see some flakes before it's all over with Friday morning. Someone in Louisiana could wind up with over 8" of snow before the event ends Friday morning, but it won't be in SW Louisiana.While I expect much of the area to see some frozen precipitation, it is a very borderline situation along I-10, and the threat for anything frozen is nearly non-existent in coastal parishes. A few sleet pellets could occur down towards Cameron, but for the most part it'll be a cold rain. Atmospheric soundings suggest the changeover to all snow will occur after midnight North of I-10, and any changeover to all snow for Lake Charles & Vicinity should be around sunrise when the atmospheric sounding will be more favorable for snow. I stress once again, that it is a very fine line for the I-10 corridor, and I am not convinced one way or the other that we'll see snow here in the Lake Area.
The surface low is advancing, and some holes have developed in the massive precip shield covering the state and SE Texas. Isentropic lift has weakened somewhat momentarily to allow for this to occur, however, a strengthening Jet Stream and the approaching ULL will create a renewed increase in the precipitation after midnight. Temperatures are in the 30s areawide, and the freezing line at the surface is slowly sliding into the forecast area. As of 11p.m. it extends from just north of POE to just north of AEX, and it will slowly sag Southward through the night. The warm layer of air aloft is eroding from North to South across the forecast region as well, and the rain/snow line currently runs from near Jasper in SE Texas to Woodworth to Natchez, MS bending SE towards McComb, MS into the extreme Northern Florida Parishes of SE Louisiana. This, too, will slowly nudge southward towards the I-10 corridor in the pre-dawn hours. Surface temperatures will likely fall below freezing for the Northern half of the area, and this is certainly where the highest accumulations will be, and the biggest travel problems as well. Surface temperatures across the Southern half of the area should remain just above freezing (33-35). Thus, limiting possible accumulations and also limiting any icy threat on area roadways for Friday morning. The expected p-types have prompted different advisories from the National Weather Service. A Winter Weather Advisory is in effect for Beauregard, Allen, Evangeline, and St. Landry Parishes in Louisiana, and Jasper, Newton, Tyler, and Jasper Counties in SE Texas. Further North, a Winter Storm Warning is effect for Vernon, Rapides, and Avoyelles Parishes in SW Louisiana. No warnings or advisories are in effect for the remainder of the forecast area, but as you can see by this map below there are winter storm warnings in effect from Texas to the Gulf Coast of Florida and over to the coast of the Carolinas.
This excitement of snow, and the troublemaker of a storm will be exiting the region by noon Friday, thus ending all chances of precipitation. Precipitation ends from West to East during the afternoon. This will allow for much improved weather conditions heading into Mardi Gras weekend. Clouds will hang around for much of the afternoon Friday, and there could perhaps be a snow flurry or two with any residual moisture in place. Not much warming is expected on Friday, and I don't believe we'll make it much above 40 across the area. Areas further North where snow will have fallen, and may be on the ground Friday morning will struggle to warm up even more so with temperatures likely no warmer than 35. A low stratus deck will be in place thanks to the usual warp-around cloudiness behind a low, and the presence of the typical low-level temperature inversion. Also, modest CAA will be in place, and this will also preclude any sufficient warm up. Some clearing will be noted late in the day, and the sun could peek out before day's end especially across the Western half of the area. High pressure quickly builds in for Friday night allowing for completely clearing skies and cold temperatures. An area wide freeze will occur Friday night with lows in the upper 20s to around freezing. This poses a bit of a problem for areas where heavy snow occurs...some snow melt will occur with temperatures above freezing Friday afternoon after the precip ends, however, not all of it will melt. The snow that did melt will likely re-freeze overnight into Saturday morning. This would result in black ice across the northern half of the area. Black ice will surely make for treacherous travel over these areas. The heavy snow itself will create some travel problems in the Winter Storm Warning area. Black ice will not be a problem for the southern half of the area as any snow will melt quickly Friday afternoon, and with drier air moving in sublimation will likely occur. Clear skies and a building high will make for a very cold start to the all important Mardi Gras weekend. Wind chills Friday night will be in the 20s, so bundle up heading out to any parades and other activities.
Sunny skies are expected on Saturday, although it will remain cool after the cold start. Highs should be in the low to mid 50s. This is still below normal for mid-February. Clouds will come right back overnight Saturday as a very quick moving system approaches for Sunday. Saturday night lows will still be on the cold side with temperatures down into the 30s again. The aforementioned system will not have ties to the Gulf of Mexico. A NW flow aloft will be established in the wake of this winter storm. This will result in a very fast moving short wave and associated cold front (Alberta Clipper) making its way into and through the area. Moisture return ahead of this fast mover will be limited, but the system itself is potent enough with its associated cold air aloft that it will be able to conjure up a brief chance of showers in the Sunday evening/Sunday night time frame. It will be far less significant that the current system. It shouldn't put a damper on any Mardi Gras parades. Temperatures ahead of this clipper will continue to moderate reaching the mid to upper 50s for highs. Clouds will increase through the day with the chance of rain in the evening hours on Valentine's Day. As quick as it comes in, it's up and gone. The slight chance of rain is maintained for Sunday night, but conditions will be turning sharply colder that night. Strong high pressure will build in its wake resulting in skies clearing overnight Sunday. The cold pattern will continue thanks to this latest front. Minimums heading into Monday will be at or just below the freezing mark.
The clipper system also signals an overall pattern shift at least temporarily. This is great news with the culmination of Mardi Gras during this forecast period. The controlling high will dominate the weather for Lundi Gras/President's Day and Mardi Gras. It will be cold on Monday and with CAA in place temperatures will struggle to get out of the 40s. You will need to bundle up as an area wide freeze is expected. This has the potential to be a hard freeze, depending on how the high orients itself of the forecast area. The clear and quiet weather will continue. The low for now for Monday stand at around 25 for AEX and POE, to around 28 at LCH, and 31 Cameron. It will be one of the coldest Mardi Gras Days in recent memory. High pressure continues to build in and will strengthen over the area, thus providing for a nice day, but cold. Highs should be around 50. The clear skies and quiet weather will prevail not only for Mardi Gras, but through the rest of this forecast period. This will be very welcomed across the area since we've been so wet this winter. It looks cold and clear for the big Krewe of Krewes Parade in Lake Charles Tuesday night. Bundle up, but leave the umbrella in the truck! Clear skies will be present, and temperatures will be in the 40s for much of the parade, but could drop into the upper 30s before it's over. CAA ceases on Mardi Gras Day, and the stage will be set for another very cold night across the forecast area. Another morning freeze will occur for Ash Wednesday morning. Temperatures should be right around 30 for a minimum. Air mass modification begins as the high weakens and shifts East. The upper level pattern seems to flatten out or go zonal after delivering another Arctic blast Sunday. Ash Wednesday highs should be in the low to mid 50s. A weak return flow commences Wednesday night as the high shifts into the SE U.S. Moisture will be slow to increase as the clipper should have pushed the 'gunk' way out into the Gulf. Dry weather will be maintained through the end of the forecast period with only some clouds noted by Thursday. The air mass modification will be slow with another cold morning on Thursday with readings in the mid 30s, while highs reach the mid to upper 50s. This is still well above the seasonal norms. Looking beyond the scope of this forecast, briefly, the next chance of showers & thunderstorms looks to arrive a week from Friday as a strong cold front moves through with another El Nino type system. Temperature modification will continue, but winter isn't over, and the unseasonably cool and unsettled pattern will return before the month is over.
Preliminary Numbers & Zone Forecast:
LCH 34/40 30/53 34/57 100 70 0 0 0 0
LFT 34/39 29/52 33/56 100 70 0 0 0 0
BPT 35/42 31/55 35/58 100 60 0 0 0 0
AEX 31/35 28/50 32/54 100 70 0 0 0 0
POE 31/36 29/51 32/54 100 70 0 0 0 0
ARA 35/41 31/53 34/56 100 70 0 0 0 0
*Winter Storm Warning until 4p.m. Friday for Vernon, Rapides, & Avoyelles Parish.*
*Winter Weather Advisory until 4p.m. Friday for Beauregard, Allen, Evangeline, & St. Landry Parish, & Tyler, Jasper, & Newton County. *
Tonight...Cloudy, Cold, & Windy with a mixed bag of precipitation. Rain before midnight, then rain mixed with sleet until 3a.m., then rain mixed with sleet and snow after 3a.m. Mix possibly changing over to all snow after sunrise. Minor sleet and snow accumulations possible. Low 34. NNE wind 15-20 mph and gusty. Wind chill 20-25. Chance of precipitation 100%.
Friday...Cloudy, Cold, & Windy with rain and snow likely in the morning. Up to 1" of snow accumulation possible. Precipitation ending around noon. Some clearing late. High 40. North wind 15-20 mph and gusty. Chance of precipitation 70%. Wind chill 20-30.
Friday Night...Becoming Clear. Cold. Low 31. NWwind 10-15 mph. Wind chill 20-25.
Saturday...Sunny. High 53. W wind 5-10 mph.
Saturday Night...Becoming Partly Cloudy. Cold. Low 34. SW wind 5-10 mph.
Valentine's Day...Partly to Mostly Cloudy with a 30% chance of rain. High 57. SSE wind 10 mph becoming NNW 15-20 mph and gusty in the afternoon.
Friday 2/12/2010 Daily Planner
7a.m.
Weather: Rain/Snow Mix
Temp: 34
Precip: 70%
Wind: N 13
W.C.: 24
Noon
Weather: Flurries
Temp: 37
Precip: 40%
Wind: N 16
W.C.: 24
5p.m.
Weather: Mostly Cloudy
Temp: 38
Precip: 10%
Wind: N 12
W.C.: 28
Drew's 7 Day Outlook
Friday
2-12-10
Weather: Rain/Snow Mix...Dusting to 1" Possible
Low: 34
High: 40
Precip: 70%
Wind: N 15-20
W.C.: 20-30
Saturday
2-13-10
Weather: Sunny
Low: 30
High: 53
Precip: 0%
Wind: W 5-10
W.C.: 20-25
Sunday
2-14-10
Valentine's Day
Weather: Partly to Mostly Cloudy w/ a Quick Shot of Showers
Low: 34
High: 57
Precip: 30%
Wind: SSE/NNW 10-20
Monday
2-15-10
President's Day
Lundi Gras
Weather: Sunny & Cold
Low: 31
High: 47
Precip: 0%
Wind: NNW 10-15
W.C.: 20-30
Tuesday
2-16-10
Mardi Gras
Weather: Sunny, Cold
Low: 28
High: 52
Precip: 0%
Wind: N 5-10
W.C.: 25-35
Wednesday
2-17-10
Ash Wednesday
Weather: Sunny
Low: 30
High: 55
Precip: 0%
Wind: NE 5-10
W.C.: 25-40
Thursday
2-18-10
Weather: Partly Cloudy
Low: 38
High: 58
Precip: 0%
Wind: ESE 10
...Marine Forecast...
*Small Craft Advisory.*
Tonight...Northeast winds 20 to 25 knots. Seas 4 to 6 feet building to 5 to 7 feet after midnight. Rain.
Friday...North winds 15 to 20 knots. Seas 5 to 7 feet subsiding to 4 to 6 feet in the afternoon. A chance of rain in the morning.
Friday Night...North winds 15 to 20 knots decreasing to 10 to 15 knots after midnight. Seas 3 to 5 feet subsiding to 2 to 4 feet after midnight.
Saturday...Northeast winds 5 to 10 knots. Seas 1 to 3 feet subsiding to 1 to 2 feet in the afternoon.
Saturday Night...South winds 5 to 10 knots. Seas 1 to 2 feet building to 1 to 3 feet after midnight.
Sunday...North winds 15 to 20 knots. Seas 2 to 4 feet. A chance of rain.
Good night and God bless!
-DM-
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