SW Louisiana Forecast Discussion...The pesky remnant low of Tropical Depression 5 continues to be the main influence on the weather across the forecast area. This is the kind of situation that can bust an entire forecast. It has really depended upon exactly where you were as to how much rain you've received over the last couple of days. We have really missed out on things here in the Lake Charles area, with just trace amounts since Tuesday. While areas further to the N and E, have seen torrential rains with over 10" in some places around Avoyelles Parish. While rainfall was limited in immediate SW Louisiana, there was a nice cloud shield in place, with the nearby convection in place. This helped keep temperatures in check with highs only reaching the mid to upper 80s with very limited amounts of sunshine. Most of the rain from today has diminished tonight, however, with the low still spiraling over the Mississippi Delta Region near Natchez, MS, nocturnal rains should fire up over night. Deep moisture remains in place. Essentially, the same air mass that has been in place since Tuesday remains in place. Therefore, rain chances will remain in the forecast for the overnight hours with generally Mostly Cloudy skies expected. Overnight minimums will be similar to the previous nights with readings in the mid to upper 70s on average. Areas which saw more rainfall today, could wind up a few degrees cooler than that, but a fairly uniform temperature regime should be in place for Thursday morning.
The same synoptic set up will prevail through Thursday as the remnant low only slowly lifts out to the NE. A deep flow of tropical moisture will continue to pump in off the warm Gulf waters. Therefore, the forecast for Thursday will be similar to Wednesday. High rain chances will be in place for the entire area, and anyone will stand the chance to see heavy rain over 2", however, I stress that once again it is a pattern that favors many of the same areas which were clobbered Wednesday being in line for a repeat performance Thursday. It is ultimately impossible to pinpoint at this time where the heaviest rains will occur, but once convection re-fires there will certainly be a heavy rain axis. The potential for more heavy rain will exacerbate the flooding situation in Central Louisiana down into portions of Acadiana (mainly the Eastern 1/3 of the area.) A Flash Flood Watch remains in effect for this area. Certainly, some heavy rain could occur in immediate SW Louisiana, but the Western portion of the forecast area is not included in the Flash Flood Watch at this time. Convection should be ongoing at sunrise, and it will grow in coverage and intensity through the morning as daytime heating is added into the equation. Enhanced rain chances and extensive cloud cover once again will limit the daytime heating potential once again. High temperatures should be at or just below average ranging from the upper 80s to lower 90s. It will continue a nice break from the intense heat that has dominated the forecast this summer. Convection will begin to dissipate late in the afternoon as the effects of daytime heating come to an end. The deep tropical moisture will remain in place, and rain chances will certainly not be reduced to zero yet. The remnant low will reluctantly push further into the Magnolia State Thursday and Thursday night, but once again the chance for overnight convection will be present. Overnight lows will be in the usual mid to upper 70s yet again.
Friday now appears the day of transition. The remnant low will continue to lift out to the NE, and the subtropical ridge of high pressure that has been a prominent feature this summer will begin to build back into the area. There will still be copious amounts of moisture in place, as it usually takes awhile for deep tropical moisture to vacate the region. Therefore, expect another decent chance of showers and storms, though it should be on a more scattered nature. Rain chances will be better than average, and should more or less be limited to the late morning through late afternoon hours. I suspect that a few nocturnal storms, and early morning storms will be possible given the deep tropical moisture. More peaks of the sun will be the offing for Friday, and temperatures should respond accordingly with maximums back closer to the norm for mid-August. Lower to middle 90s should be realized across the entire forecast area. Any heavy rains over the Eastern half of the area will still likely aggravate the flooding situation, so stay tuned. Rain chances will be highest over the current Flash Flood Watch area as they will be in closer proximity to the evacuating remnant low. Convection wanes with the loss of daytime heating, so no worries for any plans you may have Friday night.
The remainder of forecast period trends drier. The third full weekend of August promises to be very much like the first two, very hot and mostly dry. The culprit will be the building high. This will act as a mechanism of suppression. It will essentially vaporize any thunderstorms that try to develop over the weekend. One can expect no more than an isolated storm or two during the peak heating hours on Saturday. Partly Cloudy to Mostly Sunny skies are expected. Sunday will be very hot, but unlike Saturday there may be a glimmer of hope for some late day convection. All it takes this time of year is the presence of a trigger mechanism. Models suggest such a trigger mechanism may sag into the area by late Sunday (a weak, decaying cool front). This front will wash out across North Louisiana, but could certainly be close enough to send a complex of storms in our general vicinity. It is something to watch for closely, and in anticipation of this occurring a higher rain chance is reflected for this time period, albeit it's not anything out of the ordinary for late August (30%). The front will only act to serve as a potential rain maker. Don't even think about it passing through SW Louisiana. The ridge will be the dominate weather feature, so the heat will be the main story with highs reaching the upper 90s once again. Heat indices will easily surpass the danger threshold of 105 this weekend as well.
The same synoptic pattern remains in place to start the new work week Monday. The ridge continues to amplify (build) over the area, and especially to our West while an East Coast trough continues to dig towards the SE U.S. This will help keep the decaying frontal boundary in place to our North, and may result in another chance for a late day thunderstorm complex to move into the region from the NE. For the most part though, expect the drier pattern to continue with highs well above the lower 90s average for this time of year. We should easily see high temperatures in the upper 90s for most locations with the hottest localities eclipsing the century mark yet again. Heat Advisory criteria could certainly be met beginning this weekend, and definitely as we head into next week. Skies will generally start out Mostly Sunny, and become Partly Cloudy during the peak heating hours as the cumulus clouds try to build up. Morning lows should continue to average somewhere in the 75-80 range each day. Rounding out the forecast period on Tuesday and Wednesday, will be more of the same. The upper ridge remains in check. The decaying frontal boundary should be all gone by then, and this will decrease rain chances but to nearly next to nothing. I will keep in a slight chance for both Tuesday and Wednesday with the general idea that a few thermally enhanced storms will develop during the afternoon, but it will be an iffy proposition around these parts by that time. High temperatures will continue their above average trend ranging from the mid to upper 90s with a few 100s thrown in the mix, and overnight lows will be in the same 75-80 range. A brief look at the extended shows a fairly typical late August pattern to round out the month. This could certainly change as it is hard to pinpoint minor synoptic scale features that can influence the daily rain chance that may be present that far out.
Preliminary Numbers & Zone Forecast:
LCH 77/91 78/95 77/96 30 70 20 40 10 10 0
LFT 78/90 78/93 78/95 30 70 30 60 20 10 0
BPT 77/92 79/96 78/97 20 60 20 30 10 10 0
AEX 75/91 75/96 77/98 30 60 20 30 10 10 0
POE 75/91 76/95 77/98 30 60 20 30 10 10 0
ARA 78/89 79/91 78/94 30 70 40 60 20 10 0
Tonight...Mostly Cloudy with a 30% chance of showers & thunderstorms mainly towards sunrise. Low 77. Light SW wind.
Thursday...Mostly Cloudy with showers & thunderstorms likely. Locally heavy rain possible. High 91. SSW wind 10-15 mph. Chance of rain 70%.
Thursday Night...Mostly to Partly Cloudy with a 20% chance of showers & thunderstorms. Low 78. Light SW wind.
Friday...Partly to Mostly Cloudy with a 40% chance of showers & thunderstorms. High 95. SW wind 10-15 mph. Heat index values 103-108 in the afternoon.
Friday Night...Mostly Clear. Low 77. Light South wind.
Saturday...Partly Cloudy to Mostly Sunny. High 96. SW wind 10 mph. Heat index values 103-108.
Thursday 8/19/10 Daily Planner
6a.m.
Weather: Mostly Cloudy, Very Humid. Some Rain Around.
Temp: 77
Rain: 30%
Wind: SW 3
9a.m.
Weather: Mostly Cloudy. Rain Becoming More Widespread.
Temp: 82
Rain: 50%
Wind: SW 6
Noon
Weather: Mostly Cloudy. Numerous Showers & Storms.
Temp: 87
Rain: 60%
Wind: SW 12
H.I.: 95
3p.m.
Weather: Showers & Storms A Good Bet.
Temp: 91
Rain: 70%
Wind: SW 13
H.I.: 100
6p.m.
Weather: Mostly Cloudy. Showers & Storms Diminishing.
Temp: 87
Rain: 50%
Wind: SW 11
H.I.: 97
9p.m.
Weather: Mostly Cloudy. Very Humid. A Scattered Shower or Two.
Temp: 83
Rain: 20%
Wind: SW 3
Drew's 7 Day Outlook
Thursday
8-19-10
Low: 77
High: 91
Rain: 70%
Wind: SW 10-15
H.I.: 95-100
U.V.: 9- High
Friday
8-20-10
High: 95
Rain: 40%
Wind: SW 10-15
H.I.: 103-108
U.V.: 11- Very High
Saturday
8-21-10
Low: 77
High: 96
Rain: 10%
Wind: SSW 10-15
H.I.: 103-108
U.V.: 11- Very High
Sunday
8-22-10
Low: 78
High: 97
Rain: 30%
Wind: SSW 10
H.I.: 105-110
U.V.: 11- Very High
Monday
8-23-10
Low: 77
High: 98
Rain: 30%
Wind: S 10
H.I.: 105-110
U.V.: 11- Very High
Tuesday
8-24-10
Low: 79
High: 99
Rain: 20%
Wind: SSW 10
H.I.: 105-110
U.V.: 11- Very High
Wednesday
8-25-10
Low: 78
High: 98
Rain: 20%
Wind: SSW 10-15
H.I.: 105-110
U.V.: 11- Very High
...Tropics...
The tropics are eerily deceptive on this hot August night. We are watching a couple of minor tropical waves at the moment, but no development is imminent. Things will undoubtedly heat up within the next 10 days or so. No tropical cyclone formation is expected through Friday.
...Marine Forecast...
Tonight...Southwest winds 5 to 10 knots. Seas 1 to 2 feet. A chance of showers and thunderstorms.
Thursday...Southwest winds 10 to 15 knots. Seas 1 to 2 feet. Showers and thunderstorms likely.
Thursday Night...Southwest winds 10 to 15 knots. Seas 1 to 2 feet building to 1 to 3 feet after midnight. A slight chance of showers and thunderstorms.
Friday...Southwest winds 10 to 15 knots. Seas 1 to 3 feet. A chance of showers and thunderstorms.
Friday Night...South winds 10 to 15 knots. Seas 1 to 3 feet. A slight chance of showers and thunderstorms.
Saturday...South winds 5 to 10 knots. Seas 1 to 2 feet. A slight chance of showers and thunderstorms.
...Tide Data...
Thursday Tides @ Calcasieu Pass
Low: 7:10a.m. 6:24p.m.
High: 2:27a.m. 10:02a.m.
...Toledo Bend Pool Level...
167.65'
...Lake Charles Climate Summary...
Wednesday, August 18, 2010
Low: 78
Normal Low: 74
Record Low: 66-1992
High: 86
Normal High: 91
Record High: 105-1909
Rainfall
Today: Trace
Month to Date: 0.30"
Normal Month to Date: 2.65"
Year to Date: 22.68"
Normal Year to Date: 35.89"
Record: 2.00"- 1897
Sensible Weather Observed Today:
Light Rain
One Year Ago (2009)
Low: 77
High: 86
Rain: 0.16"
5 Years Ago (2005)
Low: 76
High: 95
Rain: 0.00"
10 Years Ago (2000)
Low: 72
High: 96
Rain: 0.00"
Sunrise Thursday: 6:42a.m.
Sunset Thursday: 7:50p.m.
...Lunar Table...
Full Moon- Tuesday August 24
Last Quarter- Wednesday September 1
New Moon- Wednesday September 8
First Quarter- Wednesday September 15
Have a Great Thursday & God Bless!
-DM-
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