SW Louisiana Forecast Discussion...A strong cold front moved through the area this morning, and it has been a day of CAA across the forecast area. Temperatures were much cooler than Tuesday, and much closer to normal for maximums for early December. The daytime temperatures didn't move much as the CAA negated the sunshine. The high temperature for the day occurred before sunrise ahead of the front, and the low hasn't been achieved just yet as CAA continues across the forecast area. It was a fairly nice day with plenty of sunshine this morning into the afternoon, however, high clouds streamed into the area via the Subtropical Jet Stream. A dry weather regime is expected for the next 24-36 hours as high pressure briefly rules the weather across the NW Gulf Coast. The air mass sliding into the area now is of Arctic origin, but with the overall flow the core of this Arctic air will bypass our region. We'll receive only a glancing blow from the cold weather tonight with lows ranging from the upper 20s to upper 30s. For Lake Charles & Vicinity, and other locations along I-10 temperatures will be close to freezing. Patchy frost is possible, but the air is super dry with dew points in the 20s. The high clouds streaming overhead will also serve as an inhibiting factor for frost. The orientation of the surface high will not allow winds to go dead calm overnight, so a wind chill will be a factor in the morning. Winds of 5-10 mph will result in wind chill readings in the mid-upper 20s....brrr!
Thursday should turn out to be the prettiest day of the week as high pressure will be in control. The only fly in the ointment will be the active Subtropical Jet Stream which will keep clouds streaming across the forecast area in the upper levels. These clouds will filter the sunshine for much of the day. After the cold start, it will remain on the cold side for the day as temps struggle to reach the 50s. Lower 50s seem like a good call at this point with a continued offshore flow, and the streaming high clouds. Mid and low-level cloudiness is hovering just offshore, and this will be moving inland late in the day Thursday ahead of our next weather maker scheduled to arrive Friday. It will remain dry for Thursday night, but not quite as cold. It'll still be chilly with lows down into the 30s again, but remaining above freezing. The offshore cloudiness will move in as the next system gets its act together to our SW. The pattern that we have seen so many times all ready this season, will repeat itself as we get into Friday.
An approaching short wave embedded in the predominant zonal flow will energize the aforementioned Jet Stream, and result in Gulf cyclogenesis once again. This will bring rain chances back into the forecast during the day Friday, and they will persist into Saturday as it stands now. Friday should start dry, but scattered light rain should commence around noon. Rain will become likely in the afternoon, but should mostly stay on the light side as a warm layer of air overrides the cold air at the surface (isentropic lift). The surface flow should remain either offshore or parallel to the coast. (East) The rain will increase in intensity and be heavy at times Friday night into Saturday as the low tracks close to the coast. Not much has changed as far as the onset of the rainfall, however the biggest change to this forecast is that models indicate a slowing down of the Gulf low's Eastward progression overnight Friday. For this reason, rain chances in the likely category are maintained into Saturday. 1-2" of rain is anticipated from Friday noon to Saturday noon. Higher amounts in excess of 3" can't be ruled out near the coast in the area that will be in closest proximity to the Eastward tracking Gulf low. This is just going to be a solid rain event, and no severe weather is anticipated as the warm sector remains over the Gulf. It will add to what has already been a wet start to the month of December and meteorological winter. It will continue to feel like winter as well for Friday with highs barely reaching the 50s along I-10, and likely staying in the 40s to the North. Air mass modification will begin Friday night as the low moves through the Gulf, and a WAA regime is established to erode the cold Canadian air. The pressure gradient will increase as well as the Gulf low strengthens and moves through the Northern Gulf waters. A strong East wind will likely persist along the coast from Friday afternoon through Saturday afternoon, and a coastal flood threat can't be ruled out. Inland flooding will be possible as well in areas that receive the highest rainfall especially given the fact the heavy rains occurred Monday night/Tuesday morning across lower Acadiana. Grounds are fairly saturated across the entire forecast area, and it won' take much heavy rain to create localized urban flooding. Stay tuned!
This progged low will finally be out of our hair as we head into Saturday night, and rain chances should come to an end Saturday afternoon as the low pushes towards SE Louisiana. Clouds will hang around for the remainder of the day, and hopefully begin to thin out Saturday night as drier air and weak high pressure moves in briefly. The air mass modification continues Saturday with morning lows in the mid 40s, and highs in the upper 50s. This is still just shy of normal for early-mid December. Dry weather returns for Saturday night and Sunday with temperatures switching from below normal back to above normal by Sunday as the zonal flow (W to E) strengthens across the Southern Plains. This will allow for a nice mid-December day with highs into the mid to upper 60s after a low around 50. A vigorous storm system across the Western U.S. will be marching Eastward at this time, and our break from the rain will be very brief. Clouds will roll right back in Sunday night with the impinging storm arriving for Monday. The presence of a return flow will be place ahead of this system as well. Winds will shift to onshore by late in the day Sunday and this will enhance the WAA regime that will already be ongoing.
Monday will likely start off dry, but as we get later in the day rain and thunderstorms will become likely as the rather robust Pacific storm system and its attendant cold front approaches. At this time, the models do not show the existence of a Gulf low, but the persistent zonal flow may cause the system to slow down as it moves into the forecast area Monday night. If this solution verifies, then rain chances will remain in the likely category for Tuesday. For now, the highest rain chances with this system will come Monday night as the front makes its way through the forecast area. Heavy rainfall will be possible at this time, and there should be enough instability and convective available potential energy (CAPE) for some thunderstorms. It remains to be seen if we'll have a severe weather threat, but with an active Subtropical Jet Stream in place I wouldn't rule it out. This is not forecasted at this time, as I see this as more of a heavy rain potential with 2-3" of rain expected area wide. Rainfall amounts for the Monday/Tuesday system will be pinpointed in further detail in the coming days.
I will retain rain chances into Tuesday as some overrunning moisture is progged to linger behind this boundary. This would keep it on the cool and wet side for Tuesday. Rain chances will be lower for this period, however, as the deeper moisture will be removed with frontal passage overnight Monday. A renewed CAA regime is established Tuesday, and this will take us through the end of the forecast period. Tuesday temperatures will struggle as the CAA intensifies. I will undercut model guidance at this point, as models typically have a hard time with temperatures beyond 4 days when dealing with below normal temperatures. Most numerical guidance trends back towards climatology beyond the aforementioned 4 days, and with lots of snow and cold weather up North, they will underestimate the strength of the cold air when it reaches the Gulf coast. This should be a front that taps into some of the Arctic air across the Northern half of the country. Certainly the air mass will modify on its way down, but it will be below normal especially for highs Tuesday. Morning lows will be around 50, but highs won't be much higher than that in the mid to upper 50s. A secondary front comes through on today, and clears things out in the mid and upper levels essentially ending the overrunning. A much colder night is in store for Tuesday Night/Wednesday morning with lows close to freezing again. A pattern shift at mid-week will hopefully allow for plentiful sunshine for a few days, but this is not a guarantee by any means. It will be cold with highs only near 50 and a stiff North wind prevailing. Beyond the forecast period, a cold pattern will persist. A significant freeze could occur in about a week or so. There is inconsistency across the board with the timing of the next El Nino winter pattern storm system. The consensus, however, has been for a threat for rain every 2-4 days in this pattern, and I see no reason to shy away from this idea through Christmas at the very least.
Today in Weather History...December 9: Significant Weather 3 years in a row on this date. In 2006, record cold temperatures occurred at many reporting sites across SW Louisiana as an Arctic air mass was entrenched across the area. The minimum of 24 at Lake Charles set the record for the date. Records also occurred at Alexandria (18) and New Iberia (24). Lafayette and Beaumont didn't achieve records for the day. Fast forward one year to 2007, an unseasonably warm stretch of weather occurred in early December across the region. New record highs were established for the date at Lake Charles at 82 and Alexandria came in at 83 while Beaumont joined the record party at 80. Finally, just last year in 2008, severe weather struck parts of the forecast area as a strong cold front moved through the state. Tornadoes were reported in the Alexandira-Pineville area.
Preliminary Numbers & Zone Forecast:
LCH 34/51 37/48 44/55 0 0 0 60 90 70
LFT 34/50 36/47 43/54 0 0 0 50 90 70
BPT 35/53 38/49 45/56 0 0 0 70 90 60
AEX 28/48 31/45 40/53 0 0 0 40 80 70
POE 29/49 32/46 41/53 0 0 0 50 80 70
ARA 35/52 38/50 46/57 0 0 0 50 90 80
Tonight...Partly Cloudy to Mostly Clear at times. Cold. Low 34. North wind 10-15 mph. Wind chill 23-28 by sunrise.
Thursday...Partly Cloudy and Cold. High 51. North wind 10-15 mph.
Thursday Night...Becoming Mostly Cloudy. Cold. Low 37. NE wind 10-15 mph.
Friday...Mostly Cloudy, Cold, and Windy. Rain developing and becoming likely in the afternoon. High 48. NE wind 15-20 mph and gusty. Chance of rain 60%.
Friday Night..Rain and a few thunderstorms likely. Rain heavy at times. Warmer. Low 44. East wind 10-15 mph. Chance of rain 90%.
Saturday...Cloudy with rain and a few thunderstorms likely in the morning. Rain tapering off in the afternoon. Warmer. High 55. ENE wind 15-20 mph and gusty.
Drew's 7 Day Outlook for Lake Charles & Vicinity
Thursday
12-10-09
Low: 34
High: 51
Rain: 0%
Wind: NE 10-15
W.C.: 23-28 A.M.
Friday
12-11-09
Low: 37
High: 48
Rain: 60%
Wind: NE 15-20
Saturday
12-12-09
Low: 44
High: 55
Rain: 70%
Wind: ENE 15-20
Sunday
12-13-09
Low: 49
High: 65
Rain: 0%
Wind: SE 10-15
Monday
12-14-09
Low: 53
High: 70
Rain: 70%
Wind: SSE 15-20
Tuesday
12-15-09
Low: 47
High: 54
Rain: 60%
Wind: NNW 15-20
Wednesday
12-16-09
Low: 31
High: 48
Rain: 0%
Wind: NNW 10-15
...Marine Forecast...
*Small Craft Advisory.*
Thursday...Northeast winds around 20 knots. Seas 4 to 6 feet.
Thursday Night...Northeast winds around 20 knots. Seas 4 to 6 feet. A chance of rain after midnight.
Friday...Northeast winds 20 to 25 knots. Seas 5 to 7 feet. Showers likely and isolated thunderstorms.
Friday Night...East winds 20 to 25 knots. Seas 5 to 7 feet. Showers likely and isolated thunderstorms.
Saturday...Southwest winds 10 to 15 knots. Seas 3 to 5 feet. A chance of showers.
...Tide Data...
Thursday Tides @ Calcasieu Pass
Low: 4:33a.m. 4:50p.m.
High: 10:41a.m. 8:44p.m.
...Toledo Bend...
171.04'
...Lake Charles Climate Summary...
Wednesday, December 9, 2009
Low: 43 (midnight Thursday)
Normal Low: 44
Record Low: 24-2006
High: 70 (Early Wednesday)
Normal High: 64
Record High: 82-2007
Rainfall
Today: 0.00"
Month to Date: 3.81"
Normal Month to Date: 1.31"
Year to Date: 68.35"
Normal Year to Date: 53.90"
Record: 5.89"-1967
Sunrise Thursday: 6:58a.m.
Sunset Thursday: 5:13p.m.
Thursday Hunting Times: 6:28a.m.-5:53p.m.
...Lunar Table...
Last Quarter- Tonight- December 9
New Moon- Wednesday December 16
First Quarter- Thursday December 24 (Christmas Eve)
Full Moon- Thursday December 31 (New Year's Eve)
Good night and God bless!
-DM-
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