*Blog to return to normal mode Monday.*
SW Louisiana Forecast Discussion...It's been a pretty weekend, and pretty cold! The coldest weather in 14 years is firmly entrenched across the forecast area. This will be the 4th consecutive night of hard freeze conditions, and the 6th night in the last week. It has been quite some time since we've seen some streak like this. Anything unprotected from the freezing temperatures this weekend has been zapped, and there has been associated water problems as well. The strong Arctic high has dominated the weather since Friday, and temperatures have only slowly moderated each day. Many locations didn't rise above freezing Friday with continued CAA and a cirrus shield over the area. Skies cleared Friday, and many locations dropped into the 10s. The weekend has been beautiful with not a cloud to be found, but highs struggled to reach 40 both days, with a few locations not rising above freezing on Saturday either. All locations made it above freezing this afternoon as the air mass slowly modifies. Record lows were set at many locations Saturday, and while this morning's temperatures were a few degrees colder, it was not a record cold morning as most records for January 10 are in the lower to middle 10s. Highs ranged from the upper 30s to lower 40s across the forecast area today. The Arctic high pressure, although, weakening, is centered over the state tonight. Therefore, it is going to be another night of hard freeze conditions. Light winds and clear skies will set up perfect conditions for radiational cooling. Low temperatures will be in record territory, but some upper 10s are possible once again in the coldest locations of the forecast area. Most locales should be around the low end of the 20s. The area should experience 12-16 hours of freezing temperatures, which is another bona fide hard freeze. Another hard freeze warning is in effect until mid-morning Monday.
Air mass modification is typically much slower when an Arctic air mass is involved, and that is precisely the case here. I talked all last week about how I believed the models were modifying the air mass too quickly, and you guessed it, they were! I term the modification process as slow. This will continue on Monday as the Arctic high slides to the East, and a subtle return flow will be noted. Afternoon temperatures will be a category or two higher than that of today with most locations at or exceeding the 50 degree threshold. With the large high pressure only slowly making end roads away from the area, expect another day of crystal clear skies. Wind will not be a factor, so while there will still be a noticeable nip in the air Monday afternoon, it will seem quite bearable to what it has been this weekend. Another cold night is in store Monday night as the retreating Arctic air is reluctant. A more pronounced Gulf flow will be in place due to the axis of orientation of the large high. Another freeze is expected for much of the area, but the immediate coast should avoid this one. Temperatures will range from the mid 20s to near freezing across the area. Skies should remain cloud free for this period.
At this same time, another much weaker re-enforcing shot of cold air will be working its way down the the spine of the Rockies. This re-enforcement should arrive during the day Tuesday, and will do little to affect sensible weather across the area. Moisture is very limited, and this front should move through without much fanfare. The front will bring a quick return of Northerly surface winds, but that's about it really. The modification process will temporarily halted by this front. Afternoon maxes will be very similar to that of Monday in the lower 50s. This re-enforcing shot of cold air will be more of a glancing blow, so a hard freeze is not expected as high pressure takes over briefly. A freeze will occur, marking the 6th straight night of freezing temperatures, and 8th overall this month. This will be a light freeze will minimums ranging from the upper 20s to around 32. The immediate coastline should escape a freeze once again. In other words, it will be similar to Monday night.
The clear and quiet weather will continue into the middle of the week before we see some changes. Wednesday will be another day featuring air mass modification. The weak re-enforcement high will slide Eastward during the morning hours after the light freeze, and a more significant return flow will be established. All the gunk has been shunted way out into the Gulf, and it will take quite some time for it to return. Therefore, the return flow will only help to slowly warm us up. Afternoon highs will once again be around the low to mid 50s. Clouds should begin to increase during the day as the southerly flow becomes more pronounced. Moderation increases in earnest for the Wednesday night-Thursday period. A pattern shift occurs at this point, with a split flow becoming established across the contiguous 48 states. That is, the Polar Jet will dominate the Northern half of the country, while the Subtropical Jet Stream returns and impacts the Southern half of the country. The transition period from the displacement of Arctic air to a warmer and wet period will occur in the Wednesday night-Thursday period. Temperatures will modify from below freezing to the upper 30s for Thursday morning. Clouds will be on the prowl across the area from SW to NE as our next storm system gathers, and gains strength.
The year has gotten off to a cold and dry start, but we'll make up for lost time by the end of the week. Rain chances will return to the forecast beginning Thursday afternoon. Cyclogenesis will occur in the Western Gulf of Mexico late Wednesday, and this low will slowly strengthen and ride up the coast. Also, an upper level low will form in the established split flow, and be cut off across the desert SW. Another cold front, and digging trough will be coming down the lee of the Rockies as well. What this means for the forecast area is the return of rain across the area. The forcing generated by the Gulf low will be the main focal point for rain, and isentropic ascent will be a factor on Thursday. Rain chances begin Thursday afternoon with air mass modification continuing. I expect highs to be between 55 and 60, very close to normal for mid-January. Rain chances increase further Thursday night with the low riding up the coast, and this will cause rainfall to increase and overspread the area. Could temperatures actually exceed normal by Thursday afternoon? It is possible even as warm air advection is realized across the area in response to the Gulf low. The WAA will result in much milder weather Thursday night with lows in the 40s.
While the rain will be scattered on Thursday initially, by Friday it will become widespread. The Gulf low intensifies, and may become vertically stacked. That is, low pressure in all levels...this will lead to a heavy rainfall threat. Heavy rain is expected on Friday as the low slowly moves up the coast, and into South Louisiana. It is far too early to hammer out specifics of this system, but the models are very consistent on this scenario. This looks to be the most vigorous storm system so far this season, and will certainly be El Nino enhanced. The ultimate track of the low will determine how bad the weather gets here. There is the potential for some severe weather, however, at this time I will not forecast such an occurrence. Confidence is high enough that a heavy rain and a flooding threat will be realized. Several inches of rain will be expected with this system beginning Thursday night. It may be a slow mover especially if the low becomes vertically stacked, and all of the aforementioned ingredients congeal. The worst of the weather associated with this system should come on Friday as the low ejects NE into South Louisiana. The eventual track of the low could bring it right over Lake Charles, or just to our East, that is my best guess right now. Rain and occasional thunderstorms can be expected Friday, and rain chances are already in the likely category. I believe rain chances will end up maxing out before the week is out. A temperature regime representative of normal for mid January is expected at this time with highs approaching 60 and lows in the mid 40s. Colder air will once again filter into the region on the back side of the low Friday night into Saturday. However, this will not mark an end to the precipitation as a great deal of forcing will remain in place as a result of overrunning. CAA becomes established once Friday night behind the low, and temperatures will drop back a category or two. The low will pull down some cold air in its wake, but the air mass in place at that time up North won't be near as cold as the current air mass, so it won't be cold enough for anything but rain. This low will not only be problematic over land, but over sea as well. High winds and seas will be noted beginning late Thursday through Friday over the Gulf waters.
As I said, the rain chances won't end as the low departs. The overrunning rains continue into the weekend with rain chances still in the likely category for Saturday. The threat of any convective rains should be over, but still with isentropic lift in place rain could be occasionally heavy. The CAA in the wake of the front will result in a very small diurnal range. It could turn out to be a day where temperatures are confused. It is a portion of the forecast period that will likely need some revisions later. The precipitation with this event should remain all liquid. However, by Saturday conditions will be quite raw. Temperatures will only muster the mid 40s at best as rains continue. Most of the precipitation should be light rain or drizzle. Rain chances will remain in the likely category for Saturday as well before any improvement is noted. The low will continue to pull away, and its wrap around moisture will continue to plague the area. Some improvement is in the offing for Saturday night with the departure of the low, and rain chances will be tempered downward beginning at this time. However, once again, I use the disclaimer that further revisions will likely need to be implemented for this period of the forecast. Saturday night should remain overcast, and I can't remove rain chances entirely. It will be a cold night, but nothing like we're enduring now.Minimums should be seasonably cold in the mid to upper 30s. Rain chances will diminish after midnight as I expect some drier air to move into the mid and upper levels shutting off the rain as our nemesis low turns up the East coast. The second half of the weekend looks promising at this point. While Saturday looks gloomy, and looks like a perfect day to watch the Saints playoff game, Sunday looks like a better day to do something outside after church. Clearing skies should occur during the day as a fresh area of high pressure moves in, and establishes a dry NW flow once again. Lack of Arctic air behind this system will make for a cool but not cold day with highs in the lower 50s...seasonable! Next week is trending cold once again as another shot of some Arctic air comes in, but again I stress nothing like this! It should certainly be cold enough for more freezing temperatures just beyond the scope of this forecast period. The active El Nino pattern will rear its ugly head again as we trend back towards that wet December pattern we experienced. The winter of 2009-2010 is going to the coldest winter we've had in some years!
Preliminary Numbers & Zone Forecast:
LCH 20/51 28/53 30/54 0 0 0 0 0 0
LFT 19/50 27/52 28/53 0 0 0 0 0 0
BPT 22/52 30/54 31/55 0 0 0 0 0 0
AEX 16/48 24/50 25/52 0 0 0 0 0 0
POE 17/49 25/50 26/52 0 0 0 0 0 0
ARA 21/52 27/53 29/53 0 0 0 0 0 0
*Hard Freeze Warning in effect until 10a.m. Monday.*
Tonight...Clear and Very Cold. Low 20. Calm wind.
Monday...Sunny and a bit Warmer. High 51. Light SE wind 5 mph.
Monday Night...Clear and Not as Cold. Low 28. Light SE wind.
Tuesday...Sunny. High 53. NNW wind 10 mph.
Tuesday Night...Clear and Cold. Low 30. Light NE wind.
Wednesday...Partly Cloudy. High 54. SE wind 10 mph.
Drew's 7 Day Outlook for Lake Charles & Vicinity
Monday
1-11-10
Low: 20
High: 51
Precip: 0%
Wind: SE 5-10
W.C.: 15-35
Tuesday
1-12-10
Low: 28
High: 53
Precip: 0%
Wind: NNW 10
W.C.: 25-40
Wednesday
1-13-10
Low: 30
High: 54
Precip: 0%
Wind: SE 10-15
W.C.: 25-40
Thursday
1-14-10
Low: 37
High: 57
Precip: 40%
Wind: SSE 10-15
W.C.: 30-40
Friday
1-15-10
Low: 44
High: 57
Precip: 80%
Wind: SSE/NNE 15-20
Saturday
1-16-10
Low: 38
High: 44
Precip: 70%
Wind: NNE 15-20
W.C.: 20-30
Sunday
1-17-10
Low: 34
High: 52
Precip: 20%
Wind: NNW 10-15
W.C.: 25-40
...Marine Forecast...
Tonight...Northeast winds 5 to 10 knots. Seas 2 to 3 feet.
Monday...Southeast winds 5 to 10 knots becoming south in the afternoon. Seas 1 to 2 feet.
Monday Night...Southwest winds around 5 knots becoming northwest after midnight. Seas 1 to 2 feet.
Tuesday...North winds 10 to 15 knots. Seas 2 feet.
Tuesday Night...Northeast winds 10 to 15 knots. Seas 2 to 3 feet.
Wednesday...Southeast winds 10 to 15 knots. Seas 2 to 4 feet.
Good night and God bless!
-DM-
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