SW Louisiana Forecast Discussion...The first round of rain & storms moved in right on schedule today around the lunch hour as a warm front lifted Northward. The rain & storms aided in dissipating the fog across the area which had persisted since Sunday evening. Rain occurred across the entire area, but the heaviest amounts ran from near Sabine Pass to Lake Charles to near Opelousas. In this area 1-3" of rain occurred, and with grounds already saturated across the area urban flooding was a problem this afternoon. Some strong thunderstorms occurred with strong winds, lightning and thunder. However, instability was marginal, and no severe thunderstorms occurred. It was a very mild day as expected with highs around the projected target of 70 after morning lows in the mid 50s. This was one of the few days of above normal temperatures this month...don't look for this trend to continue! Skies are overcast at the moment in the "lull" between rain makers. Some fog has re-formed over the area, and this will continue until the resumption of the rain.
The rain will return after midnight Tuesday as the strong cold front approaches the area. Widespread shower and thunderstorm activity will occur as a large convergence zone is established across the forecast area. Scattered activity has developed in the vicinity of the front back towards the Houston area. Training of storms over the same areas will occur once again exacerbating the flooding situation. Pinpointing exactly where the heaviest rain axis will set up is not an exact science, but it could very well be near the same areas that saw the heaviest rain this afternoon as leftover outflow boundaries across this area aid in development. The heavy rain will be the main threat, but some strong storms are possible as well as instability has increased a bit along with convective available potential energy (CAPE). Wind shear is lacking, which negates a tornado threat. The main threat from the thunderstorms will be the flooding threat and strong winds. No severe weather is anticipated, but there could certainly be some lighting and thunder that might give you a rude awakening towards morning. The front has been making good progress through Texas, however, due to a strong SW flow aloft over our area. The front will move through the region early Tuesday morning. It currently extends from near Shreveport to Lufkin to just North of Houston. It will ooze to the SE overnight, and enter the forecast area between midnight and 2a.m. It should reach Lake Charles proper between 4a.m. and 6a.m., and enter the coastal waters between 7 and 9a.m. Tuesday. The front combined with upper level energy over the Texas Panhandle will aid in the regeneration of the thunderstorms overnight. Widespread showers and thunderstorms (cumulilform) ahead of the front will transition to widespread rain behind the front (stratiform). Additional rainfall totals will average 1-3" while totals upwards of 5" can't be ruled out somewhere in the forecast area. The expected additional rainfall will keep the ongoing Flash Flood Watch in effect across a large portion of the forecast area. The exceptions to this watch are Beauregard and Vernon Parishes in Louisiana and Jasper, Tyler, Hardin, and Newton Counties in SE Texas. Rain chances will be maxed out across the area after midnight through at least noon on Tuesday before any improvement is noted. A mild temperature regime will continue tonight ahead of the strong cold front. Expect low temperatures to fall into the mid to upper 50s across the forecast area as colder air slowly begins to trickle into the region behind the front.
CAA strengthens during the day Tuesday, and I get the idea that the models may be underestimating the strength of the cold air behind it. Therefore, the temperature forecast for Tuesday is a tricky one. A very small diurnal range is expected, and with clouds and rain continuing for a large portion of the day temperatures may continue to fall. I will reflect this in the official forecast. I suspect we'll be in the mid to upper 50s first thing Tuesday morning, but fall through the 50s into the upper 40s by Tuesday evening. Rain will begin tapering off after noon, but light rain and/or drizzle will be possible for the remainder of the day. CAA will continue to intensify as an Arctic high pushes down into the Great Plains. Drier air will finally filter into the mid and upper levels by Tuesday night shutting off the faucet. Tuesday night will be much colder across the area, and the short-lived warm spell will be over. The reality of mid-December will be in full force at this time. Some clearing should occur for Tuesday night, but I can't guarantee that we'll clear out completely...I'll talk about why in a moment. Low temperatures will fall into the mid 30s to lower 40s for Wednesday morning. Strong Northerly winds around 20 mph will make it feel colder Tuesday night/Wednesday morning. Expect wind chills to be in the 20s and 30s across the forecast area. A rain-free forecast is indicated for Tuesday night, but by the time the rain ends Tuesday afternoon storm totals could be near 10" in some areas.
We will certainly turn colder during the day Tuesday, but will we get to enjoy some cold & dry weather for once? I am starting to doubt this possibility for the mid-week forecast period. Another digging short wave is evident on satellite imagery across the Desert SW tonight, and this will be moving to the East in the established flow across the Gulf coast. This short wave along with the active Subtropical Jet Stream could conjure up another Gulf low Wednesday night into Thursday. There is some skepticism with the models regarding whether or not this solution will occur. I am confident enough based on past experiences so far this season, that this solution may very well be correct. If there is a low, then the question is how far North does it track as some model guidance suggests the low remaining well to the South keeping moisture over the Gulf waters, and no more than overcast conditions over land. Wednesday should be a decent day, and dry for the most part with the Arctic air to our North. I expect highs to struggle to reach 50. Some intervals of sun is about the best way I can word it. It certainly doesn't look like it'll be clear at that time. High cloudiness will stream in from SW to NE across the area ahead of the next perturbation. I will keep rain chances out of the forecast for Wednesday for the time being, but depending on the speed and track of the Desert S.W. I may have to insert significant rain chances for Wednesday. However, it should be noted that the rain, if any, at mid-week will be much much lighter than what we've experienced today. CAA will continue on Wednesday despite the cloud cover and possible light rain. Temperatures will struggle to reach the 50 degree threshold. Once again, I stress that it is possible the current temperature forecast could be a bust depending on the extent of cold air to our North. Temperatures may not get out of the 40s, if we are colder than currently forecast. I will insert rain chances back into the forecast for the Wednesday night/Thursday period as the depicted Gulf low slides by to our South. Rain could become likely around overnight Wednesday. It should generally be that pesky light rain/drizzle for the most part with the best dynamics well offshore in the warm sector along a stationary front. I'll take another gander at Thursday tomorrow to see if the rain chances will indeed be back in the forecast or if we'll get to see some sunshine.
Earlier forecasts reflected near freezing temperatures for Thursday morning. This will not be the case now, with the area of low pressure expected to develop, and at the very least cloud cover will be present. This will keep temperatures reaching their maximum potential that is normally present under a clear sky. It will still be a cold start to Thursday, with another high bust potential on temperatures expected. At present, I will forecast mid 30s to lower 40s across the area. If rain is more significant on Wednesday night, then temperatures will be warmer than forecast, but if less rain occurs than a temperature closer to the freezing mark will be expected. Thursday will see Mostly Cloudy skies and a chance of cold rain in the forecast. Temperatures will struggle to surpass 50 degrees, and I will hold the maximum down several degrees below guidance based on the possibility of the underestimation of the cold air by the models, continued CAA, and the clouds and showers. This surface low should be a quick mover, and conditions should be improving late Thursday. Colder than average temperatures will prevail for this period with lows Thursday night down into the 30s with clearing skies.
Finally, the sun should be impeded on Friday as strong Canadian high pressure builds in to round out the forecast period. This will take us into pre-Christmas weekend. Dry weather with seasonably afternoon temperatures is in the offing for Friday (near 60). A brief moderation in temperatures occurs on Friday night as the strong Canadian high slides Eastward taking the main thrust of the cold air with it. A seasonably cool night is in store under clear skies and a subtle return flow. The return flow will be short-lived as another cold front will move through on Saturday. This front should move through dry, but it will pack quite a punch as it will be of Arctic origin. Right now, it looks like fropa will occur between late morning and mid afternoon Saturday. Mostly Sunny skies are expected with only an increase in wind expected to be the only sensible weather behind it. Some increased subsidence ahead of the front may allow for temperatures to reach normal levels, but CAA will quickly take over sending temperatures back the other way by Saturday night. The weekend ends on a cold note with an area wide freeze expected for Sunday morning. Once again here, the forecast models are too warm. They often have trouble with shallow Arctic air masses. Sunday should be dry and clear, but how cold will it be? This is still up for some debate as the models deliberate with each other on the extent of cold air.
The typical behavior of some numerical guidance is to trend back towards climo (normal) after 4 days. This can often lead to serious errors in forecasting. There is more data that must be analyzed when an Arctic air mass is infiltrating the contiguous 48 states. For now, I will forecast a low around 30 for Sunday and Monday as Arctic air filters into the region. I will forecast the coldest air with this blast to bypass us to the East, but it will still be very cold on Sunday and Monday. The air mass will certainly be cold enough to bring another bonified freeze to the area both mornings. Sunday highs should be in the upper 40s to lower 50s across the area. Not much change expected for Monday as the Arctic high slips closer to the forecast area. 20s are expected across a large portion of the forecast area. No precipitation chances are yielded for the Saturday-Monday period. at this time as the Arctic air mass will push all low-level moisture well out into the deep Gulf waters. There's no guarantee that we'll shunt the thrust of the Subtropical Jet Stream far enough South of us to keep high clouds out of here for a few days. However, rain chances shouldn't be a problem for this period. There lies even more dispute with the models beyond the forecast period. From what I see, all signals point to ever colder weather entering the picture just beyond this forecast period around the 23rd after a short modification trend next Tuesday. Christmas 2009 has the potential to be very cold with a hard freeze possible down to the coast. There is a lot that remains to be seen with this, but we're getting close to Christmas Day being within range of the forecast. I expect a colder than average and wetter than average pattern to continue the rest of the year. Stay tuned for more on the flooding potential through Tuesday!
This Date in Weather History: December 14, 1924...The temperature at Helena, MT, plunged 79 degrees in 24 hours, and 88 degrees in 34 hours. The mercury plummeted from 63 above to 25 below zero. At Fairfield MT the temperature plunged 84 degrees in just 12 hours, from 63 at Noon to 21 below zero at midnight.
Preliminary Numbers & Zone Forecast:
LCH 64/48 38/52 39/47 80 90 20 0 40 40
LFT 63/50 37/53 38/48 80 90 30 0 30 40
BPT 62/47 40/50 39/50 90 80 20 0 40 40
AEX 60/45 34/48 34/44 80 80 30 0 30 30
POE 60/46 35/49 36/45 80 80 20 0 30 30
ARA 65/52 41/53 40/49 90 90 40 0 30 50
*Flash Flood Watch in effect through Tuesday.*
*Dense Fog Advisory until 6a.m. Tuesday.*
Tonight...Cloudy with Areas of Dense Fog. Showers & thunderstorms likely after midnight. Rainfall heavy at times. Temperatures in the mid 60s overnight, before falling into the upper 50s around sunrise. South wind 5-10 mph becoming NNW at 15-20 mph and gusty late. Chance of rain 80%.
Tuesday...Cloudy with Showers and Thunderstorms Likely. Areas of Dense Fog dissipating early. Turning Much Cooler and Windy. Rain heavy at times in the morning. Rain tapering off to light rain and drizzle in the afternoon. High in the upper 50s in the morning falling into the upper 40s in the afternoon. NNW wind 15-20 mph and gusty. Chance of rain 90%. Total rainfall amounts 1-3" with isolated amounts up to 5" possible.
Tuesday Night...Mostly Cloudy and Colder. Low 38. NNW wind 15 mph and gusty. Wind chill readings 25-30 by sunrise.
Wednesday...Mostly Sunny early, becoming Partly Cloudy in the afternoon. Much cooler. High 52. North wind 10 mph.
Wednesday Night...Mostly Cloudy with a 40% chance of light rain after midnight. Low 39. NE wind 10 mph.
Thursday...Cloudy with a 40% chance of light rain. Cold. High 47. NE wind 10 mph.
Drew's 7 Day Outlook for Lake Charles & Vicinity
Tuesday
12-15-09
Low: 64
High: 48
Rain: 90%
Wind: NNW 15-20
Wednesday
12-16-09
Low: 38
High: 52
Rain: 0%
Wind: N 10
W.C.: 25-30
Thursday
12-17-09
Low: 39
High: 47
Rain: 40%
Wind: NE 10-15
W.C.: 30-40
Friday
12-18-09
Low: 37
High: 58
Rain: 0%
Wind: WNW 10-15
W.C.: 25-35
Saturday
12-19-09
Low: 41
High: 55
Rain: 0%
Wind: SW/NW 15-20
Sunday
12-20-09
Low: 30
High: 50
Rain: 0%
Wind: NW 10-15
W.C.: 20-25
Monday
12-21-09
Winter Solstice
Low: 29
High: 54
Rain: 0%
Wind: N 10
W.C.: 22-27
...Marine Forecast...
*Small Craft Advisory Tuesday.*
Tonight...East winds 5 to 10 knots. Seas 2 feet. Areas of dense fog with visibility 1 nm or less. Showers and thunderstorms likely in the evening. Showers and thunderstorms after midnight.
Tuesday...North winds 15 to 20 knots becoming northeast 20 to 25 knots in the afternoon. Seas 3 to 5 feet building to 4 to 5 feet in the afternoon. Areas of fog in the morning. Showers and thunderstorms.
Tuesday Night...Northeast winds 20 to 25 knots. Seas 4 to 5 feet. A slight chance of showers and thunderstorms.
Wednesday...Northeast 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.
Wednesday Night...Northeast winds 15 to 20 knots. Seas 3 to 4 feet. A slight chance of showers and thunderstorms after midnight.
Thursday...North winds 15 to 20 knots. Seas 1 to 3 feet. A chance of showers and thunderstorms.
...Tide Data...
Tuesday Tides @ Calcasieu Pass
Low: 2:54a.m. 1:36p.m.
High: 5:52a.m. 8:07p.m.
...Toledo Bend...
170.36'
...Lake Charles Climate Summary...
Monday, December 14, 2009
Low: 57
Normal Low: 43
Record Low: 24-1914
High: 70
Normal High: 64
Record High: 81-1971
Rainfall
Today: 1.39"
Month to Date: 5.77"
Normal Month to Date: 2.01"
Year to Date: 70.31"
Normal Year to Date: 54.60"
Record: 1.85"-1974
Sunrise Tuesday: 7:02a.m.
Sunset Tuesday: 5:15p.m.
Tuesday Hunting Times: 6:32a.m.-5:45p.m.
...Lunar Table...
New Moon- Wednesday December 16
First Quarter- Thursday December 24
Full Moon- Thursday December 31
Last Quarter- Thursday January 7
Good night and God bless!
-DM-
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