Wednesday, October 28, 2009
SW Louisiana Forecast Discussion...All signs continue to point to trouble tonight. A very quick turnaround is underway after a very short-lived drying trend, low-level moisture is increasing with a vengeance tonight. After a dry day with some sunshine, clouds have increased in earnest tonight and a pre-warm frontal atmosphere has enveloped the forecast area tonight. After a cool start with readings in the lower 50s, it was a warm afternoon with highs approaching 80. As of this moment, a few showers have developed across the forecast area with heavier activity over the Gulf as the warm front begins to lift Northward towards the forecast area. Showers and a few thunderstorms will move inland overnight as a strong WAA pattern continues, and the risk of rain will increase after midnight. Temperatures will be much warmer than last night, and they may actually begin rising once again overnight. The actual low will be near the current readings in the lower 70s with temperatures holding steady or rising a bit overnight. Rain chances will increase proportionally overnight with about a 30-40% chance before midnight increasing to 50-60%. after midnight. The warm front will lift through the forecast area overnight, and the entire forecast area will be in the warm sector by morning. With the warm front lifting Northward, a few thunderstorms will develop, and there will be a potential for some of these to reach severe limits. This is a pretty common occurrence with warm fronts. Another sign of the changing weather tonight is the strong wind. Southerly winds are intensifying as pressures fall across the forecast area in response to the deepening trough, and a fairly strong anticyclone over the SE U.S. The wind will continue to intensify on Thursday. Some minor coastal flooding will be possible as well as the strong Southerly winds cause tidal back up along the SW Louisiana coast; more on this in a bit. A more significant severe weather threat hangs in the balance for Thursday afternoon through early Friday. Tonight's rain will be just the beginning of a prolonged heavy rain and severe weather event.
In a situation like this, it is prudent to break it down day by day, and that is what I'll do, starting with Thursday. Conditions will worsen throughout the day with scattered showers and thunderstorms expected during the morning transitioning to numerous to widespread showers and thunderstorms in the afternoon as Jet Stream energy out ahead of the main trough sends upper level disturbances across our area from West to East. At the same time, cyclogenesis will occur in the Southern Plains, and this will only help to energize the atmosphere. A very strong Jet Stream with 70-80 kt. winds aloft will create wind shear. The end result of this will be the threat for severe weather especially during the afternoon through overnight hours. Damaging winds and isolated tornadoes will be the main threats, and I would expect a Tornado Watch to be issued for all or part of the forecast area at some point during the day. Winds will increase throughout the day as well with the strengthening storm system out West. Some gusts close to 40 mph will be possible with sustained winds over 20 mph throughout the day. As the surface low moves further East, and the trough rounds the base of the Rockies, instability in the atmosphere will increase, thus increasing the likelihood of severe weather. I will talk more on the severe weather threat in just a moment. Heavy rainfall is expected with such a high moisture content in place with the vigorous WAA pattern in place. A Flash Flood is in effect beginning Thursday morning, and will remain in effect into Friday. Several inches of rain will occur across the area, and many areas will see totals in excess of 5" with the highest amounts possibly exceeding 10" before this event is over. All of this rain will not be limited to Thursday, and there is virtually no skill in pinpointing exactly where the heaviest rain axis will be. Based on forecast models, the highest rainfall totals will be over the Western half of the forecast area from Lake Charles to Beaumont and from the coast to Toledo Bend. Certainly a heavy rain, and flood threat will occur across the entire forecast area, but based on current projections lighter amounts will occur to the East of Lake Charles. The soil is saturated across the entire area, so it won't take much rain at all to aggravate the flooding situation especially in SW Louisiana and SE Texas where the heaviest rains fell on Monday. A graphic showing rainfall accumulation through Saturday follows.
The severe weather threat reaches its maximum potential in the Thursday night time frame as the strongest Jet energy moves into the forecast area just ahead of the front. Rich Gulf air will be firmly entrenched with dew points exceeding 70 degrees across the forecast area. This is more than sufficient to support severe thunderstorms. The cold front will be sliding ESE across Texas, and be nearing SE Texas before midnight Friday. Out ahead of this line, a supercell environment may exist, that is, individual thunderstorms that become severe. Any storm that does develop in the pre-frontal warm sector will have the chance to reach severe limits, and if it bumps into an area of higher wind shear, some tornadoes are likely. Supercell thunderstorms produce the majority of all tornadoes. A squall line will initiate along the front across Texas, and move Eastward into the forecast area overnight. It should be noted here, that this line will deceivingly appear to be racing towards our area as it is effected by a faster upper level low and steering currents over Texas in closer to the deepening trough. However, as the line moves to the East the MCS will begin slow down and possibly stall out somewhere in or very near the forecast area as the steering currents collapse with the system bumping into the strong SE U.S. anticyclone. An environment that favors multiple lines is possible as embedded disturbances continue to eject out from the main system. Therefore, the highest risk of flooding and severe weather will come overnight Thursday in a 12 hour window from 6p.m. Thursday to 6a.m. Friday. Warm temperatures will remain for Thursday and Thursday night with highs reaching near 80 degrees while temperatures Thursday night only drop back to near 70. I do expect the highest rains to occur Thursday night, and at this time I will forecast the highest risk for severe weather in the forecast area to run along and North of the I-10 corridor as the best dynamics will be displaced a bit further inland from the Gulf of Mexico. I believe the heaviest rain axis will run along a SW to NE line from Houston to Lake Charles to Monroe. I strongly urge everyone to very vigilant of the weather these next couple of days. I recommend having a plan in place should flooding or severe weather occur in your area. It is a good idea to have a NOAA Weather Radio in your home, it will alert you when severe weather is expected to affect your parish or county. If you don't have a Weather Radio then I would suggest leaving on your TV or radio Thursday night when you go to sleep so you have some way of knowing what's going on. I also encourage you to text or call me if you have any weather related questions or comments...anytime day or night! I will be up all night Thursday night if I have to be, but I promise you I am totally committed to being here to serve you. I have once again included the SPC's graphic highlighting the risk of severe weather for Thursday and Thursday night.
For Friday, the system continues to dominate our weather, and models show one very hesitant system. The front will slowly trudge through the forecast area as the steering currents will favor a gradual Eastward progression. However, once the front pushes through this will not mark the end of the rain. Models indicate that while the front will push through Friday morning, the dynamics to produce heavy rain and some thunderstorms will remain in place with copious amounts of instability remaining in place across the forecast area. The severe threat and heaviest rainfall threat should shift Eastward into Acadiana at this time, but the flooding threat will continue for all of the forecast area. Another 1-2" of rain is expected on Friday as the system slowly pushes out of our area. We will switch from a very strong WAA regime to a CAA regime in the wake of the front on Friday, and as a result temperatures will be at their highest early in the morning, before falling steadily throughout the day. We'll see readings near 70 early falling through the 60s during the day. Rain will continue throughout the day, and be heavy at times as a period of overrunning is expected behind the sharp trough and cold front. Models keep delaying the departure of the rain, and now most of them keep lingering showers into Saturday morning, but I am reluctant to call for this at this point. However, that being said, I will extend the rain chances into Friday night based on the model output. This means that there may very well be rain around for High School Football, and the fields will certainly be muddy if not flooded. A very serious flooding situation could develop before all of this is over. Conditions slowly improve Friday night with rain tapering off from widespread to intermittent as drier air in the upper levels finally moves in as the trough gets an extra kick from a strong area of high pressure moving out of the Rockies. Overnight lows for Friday will be well down into the 50s. It will remain windy as well for Friday with sustained winds over 20 mph once again with gusts over 30 mph, but out of the NNW instead of SSE. This should end the threat of coastal flooding. Our attention then will turn to a river flooding situation which will likely extend into next week.
Saturday-Sunday...Drastic improvement! Clouds will linger early in the day, but clearing should occur during the day. It will remain windy and be much cooler with highs in the mid 60s at best, but depending on how long clouds linger it could barely reach 60. I will forecast ample sunshine by the afternoon hours on Saturday, and it should be a beautiful evening for Halloween. It will be cool with lows down into the 40s that night. Winds will be gusty once again on Saturday on the order of 15-20 mph as a tight pressure gradient remains in place behind the departing system. High pressure will dive SE out of the Red River Valley, and anchor over Central Texas by Saturday night resulting in relaxing winds. For Sunday, a beautiful start to November is expected with high pressure in control. After a cool start with temperatures in the mid 40s, afternoon highs will be very comfortable near 70.
For the rest of the forecast period, Monday through Wednesday....A much needed drying period will be present as the large anticyclone controls the weather, and slowly moves from West to East across the Gulf coast. Temperatures will only slowly moderate with 40s and 50s for lows, and 70s for highs for each day Monday through Wednesday. No rain is expected during this time. Looking to the extended, the dry period should continue through much of the first week of November. A return flow may return around a week from Friday as the high shifts into the SE U.S. The next rain maker may affect us over the weekend of November 7-8, but that is shear speculation at this point. The most important thing for us right now is to concentrate on the next couple of days.
Tropics: Quiet.
Preliminary Numbers & Zone Forecast:
LCH 72/81 61/72 50/64 60 100 100 100 70 0
LFT 72/82 64/73 52/62 60 100 100 100 70 0
BPT 75/82 60/72 51/66 60 100 100 100 70 0
AEX 69/80 56/66 47/59 40 90 100 100 70 0
POE 70/80 57/66 48/60 40 90 100 100 70 0
ARA 74/81 65/75 54/63 70 100 100 100 70 0
*Flash Flood Watch in effect through Friday.*
*Coastal Flood Advisory in effect through Friday.*
*Lake Wind Advisory in effect on Thursday.*
Tonight...Cloudy, Windy, and Much Warmer. Scattered showers and thunderstorms becoming more numerous late. Heavy rainfall possible at times. Temperatures holding steady or rising a few degrees between 70 and 75. SSE wind 15-20 mph and gusty. Chance of rain 60%.
Thursday...Cloudy, Windy, and Unseasonably Warm with showers and thunderstorms likely. Some severe storms possible with locally heavy rainfall expected. Rainfall amounts 1-3". High 81. SSE wind 20-30 mph with gusts to near 40 mph. Chance of rain 100%.
Thursday Night...Cloudy, Windy, and Continued Unseasonably Warm with showers & thunderstorms likely. Severe weather possible with damaging winds and isolated tornadoes. Heavy rainfall expected with rainfall amounts 3-4". Low 72. SSE wind 20-30 mph with higher gusts. Chance of rain 100%.
Friday...Cloudy, Windy, and Turning Cooler with rain and thunderstorms likely. Severe storms possible early, and heavy rain likely at times throughout the day. High 72 then temperatures falling to 61 during the day. SSW wind 20-25 mph and gusty, becoming NNW at 20-25 mph and gusty before noon. Chance of rain 100%. Rainfall totals 1-2". Storm total rainfall amounts 5-10".
Friday Night...Cloudy, Windy, and Cooler with rain likely during the evening tapering off to light rain or drizzle overnight. Low 50. NNW wind 15-20 mph and gusty. Chance of rain 70%.
Saturday...Decreasing Cloudiness, becoming Sunny by afternoon. Cool and Windy. High 64. NNW wind 15-20 mph and gusty.
7 Day Outlook for Lake Charles & Vicinity
Thursday
10-29-09
Low: 72
High: 81
Rain: 100%
Wind: SSE 20-30
Friday
10-30-09
Low: 61
High: 72
Rain: 100%
Wind: SSW/NNW 20-25
Saturday
10-31-09
Halloween
Low: 50
High: 64
Rain: 0%
Wind: NNW 15-20
Sunday
11-1-09
All Saint's Day
Daylight Savings Time Ends...Fall Back
Low: 45
High: 68
Rain: 0%
Wind: NNW 10-15
Monday
11-2-09
Low: 47
High: 72
Rain: 0%
Wind: N 5-10
Tuesday
11-3-09
Low: 48
High: 73
Rain: 0%
Wind: N 5-10
Wednesday
11-4-09
Low: 50
High: 73
Rain: 0%
Wind: NNE 5-10
...Marine...
The impinging storm will create a very strong Southerly flow across the forecast area, and this will result in higher tide levels through Friday. Minor coastal flooding is expected with water levels possibly high enough to cover Highway 82 in Cameron Parish.
Synopsis...MODERATE TO STRONG SOUTHERLY WINDS WILL PERSIST OVER THE COASTAL
WATERS THROUGH THURSDAY NIGHT AS THE AREA LIES BETWEEN THE BERMUDA
HIGH OVER THE EASTERN GULF AND DEEPENING LOW PRESSURE OVER WEST
TEXAS. A COLD FRONT WILL ENTER THE WESTERN WATERS BY MID-AFTERNOON
ON FRIDAY...CROSSING THE WATERS THROUGH THE EVENING...THEN EXIT
THE EASTERN WATERS FRIDAY NIGHT. IN ITS WAKE...MODERATE NORTHERLY
WINDS CAN BE EXPECTED. WINDS WILL DIMINISH BY SUNDAY AS HIGH
PRESSURE MOVES PAST THE REGION.
Tonight...Southeast winds 15 to 20 knots becoming 15 to
25 knots after midnight. Seas 3 to 5 feet. Isolated thunderstorms early
in the evening. A chance of showers. A chance of thunderstorms after
midnight.
Thursday...South winds 20 to 25 knots. Seas 3
to 5 feet. Isolated showers and thunderstorms in the morning...then
numerous showers and thunderstorms in the afternoon.
Thursday Night...South
winds 15 to 25 knots. Seas 3 to 5 feet. A slight chance of showers and
thunderstorms in the evening...then rain and scattered thunderstorms
after midnight.
Friday...South winds 10 to 15 knots
becoming southwest 15 to 20 knots in the afternoon. Seas 3 to 5 feet.
Rain and scattered thunderstorms.
Friday Night...Northwest
winds 15 to 20 knots. Gusts up to 35 knots in the evening. Seas 2 to 4
feet. Rain likely and isolated thunderstorms.
Saturday...North winds 15 to 20 knots. Seas 1 to 3 feet. A chance of showers.
Tide Data...
Thursday Tides:
Low: 7:25a.m. 6:51p.m.
High: 12:04a.m. 12:04p.m.
...Lake Charles Climate Summary...
Wednesday, October 28, 2009
Low: 52
Normal Low: 55
Record Low: 35-1898
High: 77
Normal High: 77
Record High: 92-1927
Rainfall:
Today: 0.00"
Month to Date: 12.65"
Normal Month to Date: 3.55"
Year to Date: 59.63"
Normal Year to Date: 47.59"
Record: 3.24"-1985
Sunrise Thursday: 7:25a.m.
Sunset Thursday: 6:28p.m.
Good night and God bless!
-DM-
