SW Louisiana Forecast Discussion...There's quite a lot on the weather menu this week. However, at Mother Nature's restaurant we don't get to choose what we want. Perhaps, somewhere in all of this I am about to divulge to you, the loyal viewer, we can find something you like...
If you like dreary, foggy days, then today was your day! Low-level moisture in place in the wake of the early weekend low pressure which brought another round of rain. We really lucked out in regards to that system, as additional activity failed to develop Saturday. However, our neighbors to the East around New Orleans were not as lucky, and there was significant flooding Saturday in many parts of New Orleans Metro. Dry weather has persisted since Saturday afternoon across the forecast area. However, very little in the way of sunshine has occurred. The original forecast for today did offer a glimmer of hope for some sunshine, but that has not been the case with the pesky low cloud deck remaining in tact. With all the moisture in place in the lower levels and a weak return flow off the warm Gulf over the relatively cooler land area, fog was an issue overnight into this morning, and this will be the case once again tonight into Monday. Fog will be the big issue tonight, but some low-level drizzle may accompany the fog as is typical with beaucoup low-level moisture in place. Temperatures will continue to be temporarily above normal for mid-December with lows into the 50s area wide. The fog never scoured out for many coastal locations today, and it remains over these areas and offshore poised to move inland tonight. I expect fog to encompass nearly the entire forecast area in some capacity by morning. A Dense Fog Advisory is in effect through 6a.m. Monday. More mixing of the atmosphere is expected beyond that time to allow the fog to scour out.
Monday will bring the return of rain across the area after a brief respite this weekend. It appears that we'll receive 2 rounds of rain this time around as a conglomeration of synoptic features sets up to produce said rainfall. First, the very active El Nino pattern continues across the Gulf Coast, and once again this will help energize the prevalent "Pineapple Express" or Subtropical Jet Stream. This will generate cyclogenesis over the Gulf waters once again, and a trailing warm front Monday morning. These will lift to the NE in tandem across the coastal waters, and into the forecast area Monday afternoon. This will result in the development of shower and thunderstorm activity by Monday afternoon. Some scattered "streamer" activity is possible during the morning hours on Monday, but the majority of the rainfall should come after noon. The warm front will move slowly inland Monday, and by midday it will reside along a NE-SW line just North of the forecast area. At this same time, the next sharpening trough and attendant cold front out West will continue its Eastward advancement. A surface low will develop over the Red River Valley In the warm sector, periodic perturbations embedded in the Subtropical Jet Stream will stream across the area out ahead of the cold front.
What does this mean for the forecast area? Rain will become likely during the afternoon hours Monday as the surface low moves up the coast. Rain will be heavy at times, and with a significant lifting mechanism in place thunderstorms are possible. The added effects of daytime heating will aid in thunderstorm genesis. I don't anticipate severe weather initially due to a lack of instability, but certainly thunderstorms are in the offing. The first round of rain should commence near lunch time, and last for the afternoon hours. As the Gulf low shifts Eastward, a temporary dry slot will move over the region. A dry period should be in place for the evening hours until around midnight or so. The second round of rain and storms will be with the front itself, but with copious amounts of low-level moisture in place extensive coverage of shower and thunderstorm activity is expected. Instability values will increase as the onshore flow strengthens in response to the cold front and advancing Red River Valley low. Heights (pressures) will continue falling through the day in response to the imposing system. Heavy rainfall is expected and the threat of organized convection will be increased with said instability in place. Severe weather can't be entirely ruled out, but I expect that it will be on an isolated basis. It is mid-December which typically isn't a prime time for severe weather, but with an El Nino pattern in place you can't completely negate this possibility. The main threat will be from the expected heavy rainfall and potential flooding threat. 1-3" of rainfall is expected across the scheme of the forecast area, with isolated amounts in excess of 5". This will add insult to injury as the grounds are already very saturated, and it won't take a whole lot to create some flooding problems. This is in particular concern for lower Acadiana, where some places received around 10" of rain last week, and then we had the additional rains early this weekend. The areas along and South of I-10 will stand the best chance to see flooding issues. However, urban and flooding in other localized areas will be possible for all areas. Pinning down specific rainfall amounts is near impossible, but a 1-3" average seems feasible. I feel models have a good handle on the situation. Mild temperatures are expected for Monday as the ongoing WAA strengthens. Maximums should be very near the 70 degree threshold. A Flash Flood Watch is in effect along and south of the I-10 corridor, but it could be extended further Northward pending revisions to the forecast. The Flash Flood Watch is in effect for Monday afternoon through Tuesday morning. Who ever dreamed that when the month started we'd be under Winter Storm Warnings/Winter Weather Advisories before we were a Flash Flood Watch? Lo and behold, that is exactly what has happened, with the snow back on the 4th and now the Flash Flood Watches for Monday.
Beyond Tuesday morning, the overall pattern shifts for the remainder of the forecast period. Hopefully, we will get some much needed to time to dry out. We will need it as it appears that when this event is over we will already have exceeded our normal monthly total for December in all locations. Some locations have already surpassed the climatological rainfall average for the month. Dry and cool to cold weather is expected Wednesday through Sunday as a large Canadian high pressure system moves down the base of the Rockies and into Texas. The cold air behind the front will have us reaching for our coats once again. Temperatures will cool off quite nicely beginning Tuesday night with lows into the mid 30s to mid 40s across the forecast area. It will remain quite windy as well as CAA processes continue into Wednesday. Wind chills by Wednesday morning will be in the mid 20s to mid 30s. Wednesday will be a cool day with highs only reaching the low to mid 50s under a full December sun. CAA wanes during the day as the large surface high settles over SE Texas by Wednesday evening. This will set the stage for a cold night Wednesday night/Thursday morning. Frosty conditions are expected across the area with a light freeze across the Northern half. Lows should be in the 30s area wide by sunrise Thursday. Conditions for Thursday afternoon should be tad warmer with maximum approaching 60.
High pressure will control the weather through Friday, so expect more cold night and pleasant afternoon with clear skies aside from a few streaming high clouds via the Subtropical Jet. Have you found something in all of this that suits your fancy yet? If not, the weather changes again over the pre-Christmas weekend. It is likely to remain dry, but by week's end a surge of Arctic air will be poised to make a run for the Gulf coast in the prevailing NW flow aloft. A dry Arctic front should move through Saturday with the only sensible weather changes expected should be a few clouds and an increase in winds. It will be morning with seasonably cold temperatures in the upper 30s to near 40. However, afternoon highs will struggle. Models currently depict lower 50s for Saturday, but beyond 5 days the numerical guidance shifts back towards climatology (normal). What this means is that the current projected high of 53 for LCH on Saturday is likely too warm. I will undercut guidance based on this. This temperature forecast is also based on the fact there is some very cold air over Canada. Of course, this air will modify as it heads towards the Gulf coast, but there will be a decent snow pack well down into the Mid West, so this will slow the modification process. I will forecast upper 40s for Saturday. A wind chill will certainly come into play as well as winds increase out of the NNW in the afternoon behind the boundary. An area wide freeze is in the offing for Saturday night/Sunday morning. This does have the potential to be a hard freeze. I will be a bit conservative at this point with the low for this period, but it certainly could well down into the 20s as opposed to the upper 20s I currently have forecasted. It will remain cold and dry for the end of the forecast period as a strong 1036 mb. high controls the weather across Louisiana on Sunday. Afternoon highs should be close to 50, still some 10 degrees below the normal values for mid-late December. We're not quite into range to give an accurate depiction for Christmas 2009, but the overall trend continues to be for colder than average. Christmas will appear within the 7 day forecast period coming up on Friday. As you can see, we certainly do have a little bit of everything on the forecast menu this week, but any rumors about more snow in the near future can be put to bed right here and right now!
This Date in Weather History...December 13: 1987...A major winter storm was blasting parts of the Southern Rockies and Southern High Plains. 25" of snow fell at Cedar Crest, NM. Wind gusts into category 3 hurricane strength range of 124 mph were reported NE of Albequerque, NM. 22.4" of snow fell at El Paso, TX included 16.8" in 24 hours. This established a single storm record for the city. The city typically only received 18.4" of snow in an entire winter season.
Preliminary Numbers & Zone Forecast:
LCH 54/70 55/58 38/53 20 80 90 80 0 0
LFT 55/70 56/60 37/54 20 80 90 90 0 0
BPT 56/71 54/58 39/55 20 90 80 70 0 0
AEX 51/68 50/54 35/50 20 80 80 80 0 0
POE 52/68 50/55 36/51 20 80 80 80 0 0
ARA 57/69 57/61 38/54 20 80 80 80 0 0
*Dense Fog Advisory in effect until 6a.m. CST Monday.*
*Flash Flood Watch in effect from Monday afternoon through Tuesday morning.*
Tonight...Mostly Cloudy with Dense Fog and drizzle forming before midnight. A slight chance of a shower after midnight. Fog reducing visibilities to less than 1/4 mile at times. Low 54. Light SE wind. Chance of measurable rain 20%.
Monday...Dense Fog early, burning off by mid-morning otherwise Cloudy with showers and thunderstorms becoming likely in the afternoon. Rain heavy at times in the afternoon. High 70. South wind 10-15 mph. Chance of rain 80%.
Monday Night...Showers & Thunderstorms likely especially after midnight. Heavy rain at times. Isolated severe storms possible. Low 55. Turning Cooler & Windy late. SSE wind 15-20 mph and gusty becoming NNW at 15-20 mph and gusty towards morning. Chance of rain 90%.
Tuesday...Showers & Thunderstorms likely in the morning. Heavy rain at times. Rain ending in the afternoon with skies clearing. Cooler & Windy. High 58. NNW wind 15-20 mph and gusty. Chance of rain 80%. NNW wind 20-25 mph and gusty. Chance of rain 80%. Total rainfall amounts 1-3".
Tuesday Night...Clear and Colder. Low 38. NNW wind 15 mph and gusty.
Wednesday...Sunny and Cool. High 53. North wind 10 mph.
Drew's 7 Day Outlook for Lake Charles & Vicinity
12-14-09
Monday
Low: 54
High: 70
Rain: 80%
Wind: South 10-15
Tuesday
12-15-09
Low: 55
High: 58
Rain: 80%
Wind: NNW 20-25
Wednesday
12-16-09
Low: 38
High: 53
Rain: 0%
Wind: N 10
Thursday
12-17-09
Low: 35
High: 57
Rain: 0%
Wind: N 5-10
Friday
12-18-09
Low: 38
High: 62
Rain: 0%
Wind: E 5-10
Saturday
12-19-09
Low: 42
High: 48
Rain: 0%
Wind: SE/NNW 15-25
Sunday
12-20-09
Low: 27
High: 51
Rain: 0%
Wind: N 10
...Marine Forecast...
Tonight...Southeast winds 5 to 10 knots. Seas 1 foot. Areas of dense fog. A slight chance of showers after midnight.
Monday...South winds 5 to 10 knots. Seas 1 to 2 feet. Patchy dense fog in the morning. A chance of rain and isolated thunderstorms in the morning...then rain likely and numerous thunderstorms in the afternoon.
Monday Night...South winds 5 to 10 knots. Seas 1 to 2 feet. Patchy fog in the evening. Scattered showers and thunderstorms in the evening...likely after midnight.
Tuesday...Northwest winds 10 to 15 knots becoming north 20 to 25 knots in the afternoon. Seas 1 to 3 feet building to 2 to 4 feet in the afternoon. Showers and isolated thunderstorms in the morning...then a chance of rain in the afternoon.
Tuesday Night...Northeast winds 20 to 25 knots. Seas 2 to 4 feet.
Wednesday...Northeast winds 15 to 20 knots. Seas 2 to 4 feet.
...Tide Data...
Monday Tides @ Calcasieu Pass
Low: 7:05a.m.
High: 2:53p.m.
...Toledo Bend...
170.45'
...Lake Charles Climate Summary...
Sunday, December 13, 2009
Low: 58
Normal Low: 44
Record Low: 18-1962
High: 62
Normal High: 64
Record High: 81-1933
Rainfall
Today: 0.00"
Month to Date: 4.38"
Normal Month to Date: 1.87"
Year to Date: 68.92"
Normal Year to Date: 54.46"
Record: 3.73"-1956
Sunrise Monday: 7:01a.m.
Sunset Monday: 5:14p.m.
Monday Hunting Times: 6:31a.m.-5:44p.m.
...Lunar Table...
New Moon- Wednesday December 16
First Quarter- Thursday December 24 (Christmas Eve)
Full Moon- Thursday December 31 (New Year's Eve)
Last Quarter- Thursday January 7
Good night and God bless!
-DM-
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