Sunday, October 25, 2009
SW Louisiana Forecast Discussion...A significant pattern shift is expected this week. After a beautiful weekend with dry and pleasant weather in place thanks to high pressure in the wake of last Thursday's cold front, this will be changing in a hurry as we start the work week. Afternoon highs on this Sunday were seasonal in the mid 70s, with very light surface winds as the high pressure controlled the weather. The anti-cyclone pushed east of the forecast area during the day resulting in the establishment of the usual return flow on the back side of a high. A very light Southerly flow is in place across the forecast area tonight, and this will only intensify as we head into Monday. With the return flow in place across the area, a moderating temperature regime will take shape as you would expect in this pattern. Overnight lows will be much warmer than those of last night. Last night minimums were in the mid 40s to low 50s, whereas tonight minimums across the region will range from the mid 50s to low 60s. Cloud cover looms just offshore, and with the onshore flow growing stronger overnight, clouds will increase across the area as well as the deeper moisture surges northward ahead of the advancing storm system. As the deeper moisture moves in, a few showers can't be ruled out especially over SE Texas towards morning, but a dry forecast is expected for the most part overnight, and I will not include a chance of rain in the zone forecast. The area of deeper moisture will move in from the SW overnight, and overspread the forecast area by morning.
On Monday, several factors will move into place to set up another heavy rain and strong thunderstorm event across the area. Deep Gulf moisture combined with energy from the Subtropical Jet Stream, a deepening trough coming out of the Rockies, and an attendant cold front, and Gulf cyclogenesis will all work in tandem to set up this rainfall event. I will dissect the system in detail. Fairly quiet weather will start our day on Monday with just cloud cover and mild temperatures in place. Some scattered air mass showers are possible during the morning mainly over SE Texas. The next cold front is already en route, and showers and thunderstorms have developed across North Texas in response to this. Some of these thunderstorms have reached severe limits, and there is a Severe Thunderstorm Watch in effect for the Dallas-Fort Worth area. This is a harbinger of things to come across our area. All of the above ingredients will help add instability to the atmosphere. Rain chances will increase throughout the day Monday, becoming likely by Monday evening as the system approaches. The biggest threat across our area at this time with this system is likely going to be heavy rain and flooding. We're still trying to dry out from the heavy rainfall last Thursday. A severe weather threat is possible as well, but where this sets up at this time is a bit suspect due to the uncertainty in the actual track of the surface low over the Gulf. My logic is that the greatest threat for severe weather will be over SE Louisiana, which should be just to the right of the NE moving surface low. Areas along and to the right of the surface low will have the the highest atmospheric shear content (wind shear). This would create an environment favorable for some tornadoes. SW Louisiana isn't entirely off the hook for severe weather, as any jaunt further to the NW of this low would place our area in a more favorable environment for severe weather. Damaging winds and large hail can't be ruled out across the area either, but at this time I expect only isolated severe thunderstorms across our forecast area. Heavy rainfall is inevitable with this system. The aforementioned ingredients will discharge a lot of energy across our area with widespread showers and thunderstorms expected. Average rainfall amounts will be on the order of 2-4" once again, on top of similar amounts we experienced last Thursday. That being said, a flood threat is shaping up, and I expect Flash Flood Watches to be issued for the entire forecast area Monday morning. The SPC in Norman, Ok doesn't currently have any areas highlighted for severe weather on Monday or Tuesday, but that could change based on the latest forecasts tonight. It wouldn't surprise me to see a Tornado Watch or two on Monday night into Tuesday morning. Moderating temperatures will continue as the low-level onshore flow intensifies ahead of the approaching font. Expect Monday temperatures to top out in the mid 70s. It will quite breezy Monday as well with a tightening pressure gradient between systems. The arrival of the more numerous shower and thunderstorm activity should be mid-late afternoon. The period of Monday night will see rain chances max out as the system advances into the region.
Slow improvement is expected for Tuesday. Showers and thunderstorms will carry over into Tuesday morning as the system slows down a bit in response to the advancing Gulf low. This will keep showers and thunderstorms in the likely category through around mid-morning to possibly as late as noon on Tuesday. Conditions improve in the wake of the front Tuesday afternoon with rain ending and clouds clearing late in the day. This is a cold front of Pacific origins, so only a modest cool down is expected in the wake of the front. Somewhat cooler conditions are expected for Tuesday afternoon with highs in the upper 60s to lower 70s. There won't be much of a diurnal range at all on Tuesday thanks to the rain in the morning, and CAA pattern in the afternoon. A brief respite is in store for the Tuesday afternoon through Wednesday period. Pleasant weather prevails Tuesday night with seasonable temperatures down into the lower 50s. A nice day is expected Wednesday as high pressure briefly controls the weather once again. Highs should be in the mid to upper 70s. As quick as the high moves in, it moves out as a very progressive El Nino pattern continues. The return flow is re-established in earnest late Wednesday bringing back the clouds and humidity.
Models depict an even deeper trough hanging in the balance for the Thursday-Thursday night time frame. Showers and thunderstorms will certainly be inevitable once again, and another heavy rainfall event is expected. Severe weather could also be a very real possibility with this system as well, especially with the deepening trough. In an El Nino pattern, there is typically added energy from the persistent Subtropical Jet Stream, and you have to figure this will factor into the equation with this second system as well. I won't hit any specifics of this system too hard just yet, as it is prudent to get rid of Monday's system first. However, I will say that this system will likely only add to the flooding potential this week, as another several inches of rain is expected. There is some uncertainty as to how long it will take this system to depart. Some forecast models suggest that this system will slow down as a high pressure over the SE U.S. strengthens. It will slow down as it bumps into the controlling high. If this occurs, then it is likely that the threat for heavy rainfall and strong storms will continue into Friday. While other solutions, show improving conditions during the day Friday. At this point, I expect the worst of this system to be during the day Thursday, with some lingering shower activity behind the front on Friday before conditions improve Friday afternoon. A sharper trough with this second system, will likely mean a sharper cool down in its wake just in time for the weekend. Temperatures for the Thursday period will be very mild with lows well up into the 60s and highs approaching 80. Somewhat cooler weather moves in for Friday as the coolest air will be lagging a bit behind the front. Not much of a diurnal range is expected Friday, and I don't expect temperatures to get above 70 at this point.
As for the weekend....It looks very nice at this point with high pressure moving in, and hopefully setting us up for our third beautiful weekend in a row. Depending on just how sharp the trough is, there is the potential for temperatures next weekend to be the coolest we've seen so far this season. Lows could be well down into the 40s while highs remain shy of 70 degrees. It will be very welcomed by this time as we will certainly need some time to dry out after the two systems affecting us this week. This is good news for Halloween, and the plethora of activities planned that go with it. Not really weather related, but of note for next weekend, is the time change. Beyond the forecast period, as we head into November, believe it or not, the overall highly progressive pattern will continue with another strong system within the first few days of November. This is not a forecast of course, but it is a pattern and one that certainly seems favorable giving the active El Nino pattern that occurs around these parts. Stay tuned throughout the day Monday for more weather information!
Tropics: The tropics are quiet as can be as we enter the last 5 weeks of the season. It will likely stay that way as water temperatures continue to cool, and a highly sheared environment remains in place over the majority of the Atlantic basin in response to the strengthening El Nino.
Preliminary Numbers & Zone Forecast:
LCH 59/75 58/69 52/76 0 40 100 80 0 0
LFT 57/76 59/70 51/75 0 30 100 90 0 0
BPT 62/77 57/71 53/77 0 50 100 80 0 0
AEX 53/78 55/67 48/73 0 60 100 80 0 0
POE 53/78 54/68 49/74 0 60 100 80 0 0
ARA 58/77 60/70 54/77 0 30 100 90 0 0
Tonight...Increasing Cloudiness and Warmer. Low 59. Light SE wind.
Monday...Mostly Cloudy with Some Scattered Showers in the Morning. Scattered Showers & Thunderstorms in the Afternoon. Heavy Rainfall at Times. High 75. SSE wind 15-20 mph and gusty.
Monday Night...Cloudy with Showers and Thunderstorms Likely. Heavy Rainfall at times with localized flooding expected. Some Severe Storms Possible. Turning Cooler after Midnight. Low 58. SSW wind 15-20 mph and gusty. Chance of Rain 100%.
Tuesday...Cloudy with Showers and Thunderstorms Likely in the Morning. Rain Ending with Decreasing Cloudiness in the Afternoon. Cooler. High 69. NNW wind 10-20 mph and gusty. Chance of Rain 80% in the morning.
Tuesday Night...Clear. Low 52. Light NE wind.
Wednesday...Mostly Sunny. High 76. NE wind becoming SE 5-10 mph.
7 Day Outlook for Lake Charles & Vicinity
Monday
10-26-09
Low: 59
High: 75
Rain: 40% PM
Wind: SSE 15-20
Tuesday
10-27-09
Low: 58
High: 69
Rain: 80% AM
Wind: NNW 10-20
Wednesday
10-28-09
Low: 52
High: 76
Rain: 0%
Wind: NE/SE 5-10
Thursday
10-29-09
Low: 64
High: 78
Rain: 70%
Wind: SSE 15-25
Friday
10-30-09
Low: 65
High: 68
Rain: 60%
Wind: NNW 15-20
Saturday
10-31-09
Halloween
Low: 46
High: 64
Rain: 0%
Wind: NNW 10-15
Sunday
11-1-09
All Saints Day
Daylight Savings Time Ends...Fall Back!
Low: 43
High: 67
Rain: 0%
Wind: N 5-10
...Marine Forecast...
Tonight...Southeast winds 15 to 20 knots. Seas 3 to 4 feet. A slight chance of showers after midnight.
Monday...Southeast
winds 15 to 20 knots. Seas 4 to 5 feet. A slight chance of showers and
thunderstorms in the morning...then showers and thunderstorms likely in
the afternoon.
Monday Night...Southeast winds 15 to 20
knots becoming southwest after midnight. Seas 5 to 6 feet building to 6
to 7 feet after midnight. Showers and thunderstorms.
Tuesday...West
winds 15 to 20 knots. Seas 6 to 7 feet subsiding to 3 to 5 feet in the
afternoon. Numerous showers and thunderstorms in the morning...then a
slight chance of showers in the afternoon.
Tuesday Night...West winds 10 to 15 knots becoming south 5 to 10 knots after midnight. Seas 2 to 4 feet.
Wednesday...Southeast winds 15 to 20 knots. Seas 4 to 6 feet. A slight chance of showers and thunderstorms.
...Tide Data..
Monday Tides:
Low: 4:01p.m.
High: 12:04a.m. 11:58p.m.
...Lake Charles Climate Summary...
Sunday, October 25, 2009
Low: 50
Normal Low: 56
Record Low: 36-1999
High: 76
Normal High: 78
Record High: 92-1927
Rainfall:
Today: 0.00"
Month to Date: 7.27"
Normal Month to Date: 3.19"
Year to Date: 54.25"
Normal Year to Date: 47.23"
Record: 7.00"-1900
Sunrise Monday: 7:23a.m.
Sunset Monday: 6:31p.m.
Good night and God bless!
-DM-
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