SW Louisiana Forecast Discussion...The advertised elongated Gulf trough is controlling the weather across the forecast area on this Wednesday evening. Scattered showers and storms dot the landscape at random at this hour, and have been sporadic across the entire forecast area all afternoon. Granted, the coverage has not been as great as the previous forecast indicated it would be. Of course, all of this convective activity is thermally induced, and the elongated trough has helped to act as a trigger or focus mechanism for additional development. It was still a hot late July day as you would imagine with temperatures easily into the 90s once again. The chance for any shower or storm will continue through the evening hours, but all convection should receive a cease and desist letter within an hour or two after sunrise. Overnight lows should be very similar to what they have been for the majority of the summer...mid to upper 70s. A light onshore flow will prevail through the overnight hours.
The latter half of this work week offers a drier solution as riding processes take shape once again. The mid and upper levels will dry out, but of course the moist layer at the surface will remain intact. The end result will be a reduction in the daily probabilities of rain chances. Thursday will essentially be a day of transition as the ridge builds in, and the departing Easterly wave moves out of the picture. This translate into a day where the forecast area should see about average coverage of the typical scattered afternoon convection. The sea breeze should initiate the initial shower and thunderstorm activity by mid-day, with additional storms firing during the afternoon strictly on a hit or miss basis as the convective temperature is realized. The average chance for rain this time from day to day is 30%, and I see no reason to deviate from this number for Thursday. High temperatures again also trend above normal as we lower the risk of storms. Average highs should be in the low to mid 90s on Thursday with heat indices running in the 102-107 range during the afternoon.
The atmosphere continues to dry out further as we head into Friday with the ridge having a firm grip on the atmosphere. Also, aiding in drying out the atmosphere is what should be some sort of tropical system over Florida by that time. This is Invest 97L which I mentioned yesterday. The good news is that the system is less organized today than it was 24 hours ago. It is trying to maintain itself, and fight off some shear to the NW of the system. More on the system itself shortly in the tropical update. Regardless of what this system does as far as development is concerned, it will continue to move WNW and is on a course to enter the Gulf of Mexico this weekend, most likely late Friday or Saturday. The circulation around this system will allow drier air to stream into the area. Only a very slight chance of afternoon showers and storms is expected on Friday and Saturday as the atmosphere will remain largely capped, and most of the vertical growth will be prohibited. Mostly Sunny to Partly Cloudy skies are expected each day. Temperatures will trend above normal as well with readings expected to be in the mid to upper 90s. The tropical surge will continue its W to WNW motion at the same time, and should be in the Eastern Gulf waters by Saturday afternoon. Any stray storm that does develop Friday or Saturday will decay by nightfall...the usual summer deal.
The forecast for the latter half of the weekend into early next week is up in the air. It all hinges on the developments of Invest 97L. The weather will become more adverse the stronger this tropical entity gets. For now, it appears that it is a given that moisture will increase across our part of the world as we head into the second half of the weekend. The ridge will begin weakening on Saturday as the tropical moisture bumps into it. Further fine tuning is likely over the next few days, but for now the forecast will certainly reflect the increasing moisture for the Sunday-Monday time frame. Rain chances could very well end up in the likely category, but at this time I will kind of broadbrush it due to the high amount of uncertainty. Both Sunday and Monday will see higher rain chances, but at this point the jury is still out on which day will be the most likely that we'd see rain...again it all practically depends on the future developments of 97L. Most of the forecast models do suggest it will reach the Gulf, and the current forecast is based on an average of the models as well as the official NHC forecast. As far as how strong this system will be, there are many parameters to be discussed, and I will do that in the tropical section as mentioned a few moments ago. Certainly though, the increased rain chances and the threat for some heavy tropical downpours will be realized based on the current projections. Temperatures will decrease as a result of the increased tropical moisture. Expect highs to be a bit cooler than the average with readings near 90 both days. The rest of the forecast period is also in question. The first surge of tropical moisture should be out of our hair by Tuesday, but if some models are correct there might be another influx of deep tropical moisture hot on its heels to move our way by the end of the forecast period on Wednesday. There is still much speculation on this idea as well. Nevertheless, rain chances will remain at or above normal through the end of the forecast period. I will drop them back slightly for Tuesday to indicate the brief reprieve, but they should only increase again on Wednesday. Partly to Mostly Cloudy skies are expected for Sunday-Wednesday with rain chances possibly extending into the likely category each day except Tuesday. High temperatures will remain at or just below the norm, and low temperatures will likely continue to trend above normal through the forecast period. July is our wettest month, and if some of the current projections are correct this last week of July would certainly foot that bill. Looking beyond the scope of this 7 day forecast just briefly, a return to a nearly normal summer pattern should take over by month's end after the secondary surge of tropical moisture vacates the region. Hot and humid conditions will prevail, and all eyes will continue to be on the tropics as we enter August, the beginning of prime time hurricane season.
Preliminary Numbers & Zone Forecast:
LCH 76/94 77/95 77/96 0 30 0 20 0 20
LFT 77/94 76/95 77/96 0 30 0 20 0 20
BPT 77/95 77/96 76/97 0 30 0 20 0 20
AEX 75/96 75/97 75/98 0 20 0 20 0 20
POE 75/95 76/96 75/98 0 20 0 20 0 20
ARA 78/93 77/93 78/95 0 30 0 20 0 20
Tonight...Partly Cloudy becoming Mostly Clear. Low 76 Light SE wind.
Thursday...Partly Cloudy with a 30% chance of scattered afternoon showers & thunderstorms. High 94. SSE wind 10-15 mph.
Thursday Night...Mostly Clear. Low 77. Light SE wind.
Friday...Partly Cloudy with just a 20% chance of a scattered afternoon shower or storm. High 95. SSE wind 10-15 mph. Heat index value 102-107 in the afternoon.
Friday Night...Mostly Clear. Low 77. Light NE wind.
Saturday...Partly Cloudy with just a slight 20% chance of a scattered afternoon shower or storm. High 96. NE wind 10-15 mph. Heat index value 103-108 in the afternoon.
Thursday 7/22/10 Daily Planner
6a.m.
Weather: Mostly Clear
Temp: 76
Rain: 0%
Wind: SE 3
9a.m.
Weather: Partly Cloudy
Temp: 83
Rain: 10%
Wind: SSE 7
H.I.: 91
Noon
Weather: Partly Cloudy, Scattered Storms Developing
Temp: 89
Rain: 30%
Wind: SSE 11
H.I.: 97
3p.m.
Weather: Partly Cloudy, Scattered Showers & Storms
Temp: 94
Rain: 30%
Wind: SSE 13
H.I.: 103
6p.m.
Weather: Partly Cloudy
Temp: 90
Rain: 20%
Wind: SSE 12
H.I.: 100
9p.m.
Weather: Mostly Clear
Temp: 84
Rain: 0%
Wind: SSE 5
H.I.: 91
Drew's 7 Day Outlook
Thursday
7-22-10
Low: 76
High: 94
Rain: 30%
Wind: SSE 10-15
H.I.: 100-105
U.V.: 10- High
Friday
7-23-10
Low: 77
High: 95
Rain: 20%
Wind: SSE 10-15
H.I.: 102-107
U.V.: 11- Very High
Saturday
7-24-10
Low: 77
High: 96
Rain: 20%
Wind: NNE 10-15
H.I.: 103-108
U.V.: 11- Very High
Sunday
7-25-10
Watching the Tropics
Low: 77
High: 91
Rain: 50%
Wind: ESE 15-20
H.I.: 100-105
U.V.: 9- High
Monday
7-26-10
Watching the Tropics
Low: 77
High: 90
Rain: 60%
Wind: SSE 15-20
H.I.: 98-103
U.V.: 8- High
Tuesday
7-27-10
Low: 76
High: 93
Rain: 40%
Wind: SSE 10-15
H.I.: 101-106
U.V.: 9- High
Wednesday
7-28-10
Low: 77
High: 92
Rain: 50%
Wind: SSE 10-15
H.I.: 97-102
U.V.: 8- High
...Tropical Update...
The tropics are certainly showing signs of heating up. As I touched on briefly in the forecast discussion, we continue to monitor Invest 97L in the Caribbean. The system has struggled to get better organized over the last 24 hours. A strong upper level low to the NW of the system is producing significant enough wind shear over the Central Caribbean that is inhibiting development. Remember, wind shear doesn't make for a favorable environment to develop. The system is trying to get more organized, and this will likely be the story for the next 24 hours. The environment over the Caribbean is not incredibly favorable for development over the 24 hours, but as the upper level low pushes off to the WNW, the environment over the Western Atlantic and Caribbean will gradually become more favorable for development. There is currently some dry air entrainment and wind shear impacting the west side of the circulation, and the present low-level center is displaced from the deep convection. The low-level center is exposed to the WSW of the main convection. If the shear relaxes, then the center will try to re-form underneath the deep convection. This would be a sign of better organization, and the chances of development would increase. Invest 97L will be in the general vicinity of The Bahamas Thursday, and near or over portions of South Florida on Friday. Of course, interaction with landmasses will inhibit development. However, I believe that as 97L moves into a more favorable environment through Friday, some slow development will occur. An Air Force Hurricane Hunter will investigate the system on Thursday. As of right now, there is a medium chance or 40% chance of development.
The impacts of land and a marginally favorable environment will likely keep Invest 97L from becoming a strong system, but I do believe it will become a Tropical Depression by Friday, and Tropical Storm Bonnie or Colin over the weekend. The future track and intensity of 97L remains uncertain, but as I stated previously it should be near or over portions of Florida on Friday. After this point, Invest 97L is forecast to enter the Gulf of Mexico over the weekend, and continue on a WNW heading around the base of the Bermuda High. Much of the model guidance is clustered on Louisiana, and the official forecast based on the forecast models from the National Hurricane Center bring the center of Invest 97L in the general vicinity of Louisiana late in the weekend or early next week. This forecast seems logical, but what is uncertain is the intensity forecast. The models diverge on their intensity forecast. Some models leave the system as an open wave while the majority of them suggest a Tropical Storm will form. A few outliers suggest a minimal hurricane will develop. Given the current marginally favorable environment and the expected interaction of land, it is feasible at this point in time to believe that this will remain a weak system. I believe this system will become a tropical storm over the weekend. Heavy rainfall will occur over the Caribbean and portions of Florida, Cuba, and the Bahamas through Friday. Based on the current track, the system is expected to increase moisture and elevate rain chances across our area by Sunday. It remains to be seen how much rain we will see from this system here across the forecast area. Certainly, a stronger system would mean more adverse conditions, but at this point whether it's a tropical wave, depression, or tropical storm will essentially just make it a heavy rain producer. Of course, conditions will be more adverse along the coast and over the coastal waters as an increase in winds and seas will be noted. Even a weak system on this track, will pose problems for the cleanup operations of the Gulf oil spill. There is still a possibility that the best case scenario will unfold, but this seems unlikely at this point. The best case scenario would be for the shear to win out and tear the tropical wave apart. If this were to occur, then there would not be much left of the circulation, and ultimate dissipation would occur especially given the interaction with land. Stay tuned for more information in regards to this system.
Elsewhere, no tropical cyclone formation is expected through Friday.
...Marine Forecast...
Tonight...Southeast winds 15 to 20 knots. Seas 2 to 3 feet. Scattered showers and thunderstorms.
Thursday...Southeast winds 10 to 15 knots. Seas 1 to 3 feet. A slight chance of showers and thunderstorms.
Thursday Night...Southeast winds 10 to 15 knots. Seas 1 to 3 feet.
Friday...Southeast winds 5 to 10 knots. Seas 1 to 3 feet subsiding to 1 to 2 feet in the afternoon.
Friday Night...Southeast winds 5 to 10 knots becoming east after midnight. Seas 1 to 2 feet.
Saturday...Northeast winds 10 to 15 knots. Seas 1 to 2 feet. A chance of showers and thunderstorms.
...Tide Data...
Thursday Tides @ Calcasieu Pass
Low: 8:06a.m. 7:24p.m.
High: 3:26a.m. 11:05a.m.
...Toledo Bend Pool Level...
168.18'
...Lake Charles Climate Summary...
Wednesday, July 21, 2010
Low: 77
Normal Low: 75
Record Low: 65-1910
High: 93
Normal High: 91
Record High: 99-1937
Rainfall
Today: 0.00"
Month to Date: 3.04"
Normal Month to Date: 3.44"
Year to Date: 18.56"
Normal Year to Date: 31.71"
Record: 4.50"-1917
Sensible Weather Observed Today:
None
One Year Ago (2009)
Low: 73
High: 89
Rain: 0.45"
5 Years Ago (2005)
Low: 75
High: 94
Rain: Trace
10 Years Ago (2000)
Low: 75
High: 96
Rain: 0.00"
Sunrise Thursday: 6:26a.m.
Sunset Thursday: 8:13p.m.
...Lunar Table...
Full Moon- Monday July 26
Last Quarter- Tuesday August 3
New Moon- Tuesday August 10
First Quarter- Monday August 16
Have a Great Thursday & God Bless!
-DM-
Gosh Drew the tropics are really busy-thanks for doing such a great job at keeping us posted...! Shantele
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