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SW Louisiana Forecast Discussion...Winter has returned with a vengeance after a brief hiatus. The much advertised strong cold front rolled through the forecast area with ease this afternoon. A thin line of showers moved through just ahead of this Arctic front. There was not much rainfall expected with the front, and that is exactly how it played out as the atmosphere remained largely capped. The cold front put an abrupt end to the relatively mild weather of the past few days, and temperatures are taking a downward spiral tonight. High temperatures actually warmed to above normal levels reaching the mid to upper 60s in most locations until the front came through at mid-afternoon. Skies remain overcast for the time being, and there is leftover moisture in the boundary layer as the deeper cold air lags behind for a time. This will result in patches of light rain or low level drizzle for much of the night, but the odds of any measurable precipitation are only about 20%. Additional totals will be from a trace to a few hundredths of an inch. The boundary layer begins to dry out after midnight as the cold air becomes deeper, thus all rain chances will come to an end. Skies will begin a slow clearing in the early morning hours of Friday as a strong area of high pressure slides down the base of the Rockies towards the Gulf Coastal Plain. Temperatures will fall steadily all night long, eventually bottoming out in the low to mid 30s across the area. The northern half of the region is under a Freeze Warning as temperatures will undoubtedly be below freezing for about 3-6 hours. We will not only have the cold temperatures to deal with, but also the wind. Winds have increased significantly in the wake of the front due to the typical pressure anomalies. Winds are gusting over 20 mph quite consistently, and this trend will continue through the night. This will add insult to injury as wind chills will fall into the upper 10s to lower 20s by sunrise...brrr! A wind advisory has been issued by the National Weather Service for the parishes and counties along and South of I-10.
A period of benign weather is on tap as we round out this work week and head into the weekend. It will remain on the cold side with highs and lows both below normal. CAA continues in earnest on Friday. High temperatures will fall short of the 50 degree mark despite sunshine for the majority of the day. Clouds will linger in the morning hours, but we should be completely cleared out by noon or so. Winds will gradually subside through the day as a strong 1040 mb. high moves much closer to the area. It will be in the vicinity of the Red River Valley by Friday afternoon. The stage will then be set for another freeze for Friday night-Saturday morning. This one will affect all areas. Hard freeze conditions will likely be met North of I-10 with a moderate freeze here in the Lake Area. The coastline will experience a light freeze with temperatures bottoming out around 31 or 32 first thing Saturday morning. The wind will calm down overnight as the area of high pressure moves into East Texas. The lighter winds and clear skies will aid in radiational cooling. It will be the opposite of tonight which is an advective cooling event. The wind chill (apparent temperature) will be very close to if not the exact same as the actual temperature since the winds will be very light by sunrise Saturday.
Saturday will be a beautiful day even with the cold start. This Arctic air mass is not nearly as cold as its predecessor from last week, and we're also only receiving a glancing blow. Therefore, air mass modification will be an easier process. The full sunshine expected on Saturday will help temperatures warm up to the mid 50s, that's still below normal, but it'll certainly feel better than the mid 20s in the morning. Modification continues Saturday night, but it'll still be on the cold side with a light freeze for all but the coastline. Clear skies will remain in place, and CAA will cease with a predominant Easterly flow in place. Frost seems like a good bet for Sunday morning with light surface winds and clear skies in place. Sunday won't be too bad of a day, but if I had to pick a day this weekend it would be Saturday. Sunday will start out nice and clear with the cold start, but clouds will increase as the day progresses. A very fast upper level pattern exists across the contiguous 48 states, and our next system will already be moving into range on Sunday. We will transition from Mostly Sunny to Mostly Cloudy by day's end, and I wouldn't rule out some isolated showers in the afternoon hours as low level moisture and lifting increases. This next system is a cold front as well, but there will be a short wave ejecting out ahead of this system due to the active Jet Stream. This will bring rain chances back into the forecast for the Sunday night period. High temperatures on Sunday will remain below normal levels reaching the mid to upper 50s across the area.
This next system should provide a better shot at more beneficial rain after today's subpar rainfall totals. Better lifting and dynamics will be in place overnight Sunday into Monday as the short wave and front work in tandem to produce the expectant rainfall. Mostly general rains are expected, but there may be enough instability for a few rumbles of thunder. The risk of convection will be greater up above the surface due to isentropic ascent. The pattern favors slantwise convection. Models are diverging on timing and strength with this system. The GFS suggests a faster and weaker system with less rainfall while the European (ECMWF) suggests a slower and stronger system with more rainfall. I surmise that it is best to take an average of the models at this point. The best opportunity for rainfall will come overnight Sunday through about noon Monday. Rainfall could potentially be heavy briefly, but again I believe this type of set up will generally support just a soaking rain. Rainfall amounts up to an inch are possible. The forecast will reflect likely rain chances for Sunday night and Monday. While air mass modification will occur with a subtle return flow in place, it won't be all that warm. Temperatures will be around normal for lows in the upper 30s to lower 40s. Temperatures may very well be confused on Monday dependent upon the timing of the latest front. This front will essentially re-enforce a Canadian air mass over the area. Temperatures may fall during the day Monday, and I believe models are a tad warm given the timing and strength of the system. Models may very well be underestimating the amount of cold air this front will pull down via the NW flow aloft. Temperatures will be hard pressed to rise much, and I will undercut guidance holding maximums in the 40s at best for now. It will become quite windy as well in the wake of the front, so Monday may very well turn out to be quite a raw day.
Conditions improve Monday night, but we will continue the trend of below normal temperatures thanks to renewed CAA behind the morning front. Skies will clear as high pressure slides down the lee side of the Rockies. Overnight lows will be close to the freezing mark. An active Subtropical Jet Stream may prevent us from going completely clear as some high cloudiness streams overhead, but certainly drier air at the surface will preclude any rain chances for the Monday night and Tuesday period. The NW flow aloft will continue, and with a good deal of sunshine expected Tuesday we won't warm up all that much. It will remain breezy as well with the typical pressure differences in place yet again. The colder air will work its way into the Gulf. This will be a similar pattern to the one we experienced between the 10th and 14th of the month. The air mass may not be quite as cold as it was then, but we will certainly need coats and winter wraps. Forecast highs for Tuesday will generally be in the mid to upper 40s, well below the lower 60s normal. Another cold night is in store for Tuesday night with another light freeze expected for most, with the potential for hard freeze conditions North of I-10. The high clouds may limit ideal radiational cooling conditions. Some models indicate re-enforcement fronts to push a secondary surge of Arctic air towards the Gulf coast. This trend is being monitored.
Models are insistent on carving out another short wave in the active NW flow. This short wave will pass through the area at mid-week, however, it will be moving over a very moisture starved environment. Rain chances are negligible at this point, but there could be enough upward motion (lift) to generate some light cold rain on Wednesday. For now, the forecast just reflects an increase in cloud cover, and a reduction in temperatures. It will be a rather cold day with morning lows at or near freezing, and only warming to the mid 40s at best depending on how much cloud cover is present. What may end up happening, as is often the case with entrenched Arctic air, is that the precip may fall as virga. Remember, virga is precipitation that falls, but evaporates before reaching the ground. The timing of said short wave is still in question with some model runs suggesting it crossing the area on Tuesday into Tuesday night hot on the heels of the Monday system. For now, I will let the idea of this happening on Wednesday stand. Cold weather will be with us to round out this forecast period on Thursday, as a series of Canadian highs keeps a NW flow entrenched over the area. You can't ignore the cold air that continues to build up over Western Canada. Models have a hard time with this, so I get the feeling it will be colder than models currently depict. Skies should be clear for Wednesday night into Thursday as the short wave departs taking the cirrus shield with it. A morning freeze, possibly a hard one, is on tap for Thursday. Upper 20s are shown for now, with the idea that it could more like the mid 20s. Highs will be well below normal as well holding in the 40s even with plenty of sunshine. The offshore flow at the surface will be maintained. The colder than usual pattern with a continued fast upper level flow sending fronts forth every few days looks to continue beyond this forecast period, and for the rest of the month. Long range models indicate the possibility of a big time Arctic outbreak around the 1st of February, which if it occurs, could ultimately bring us the colder air so far this season. I'll be watching with two open eyes here in the Weather Center!!!
Preliminary Numbers & Zone Forecast:
LCH 34/49 27/55 31/58 20 0 0 0 0 0
LFT 35/48 27/54 30/57 30 0 0 0 0 0
BPT 36/50 28/56 32/58 20 0 0 0 0 0
AEX 30/45 23/51 28/55 20 0 0 0 0 0
POE 30/45 23/51 28/55 20 0 0 0 0 0
ARA 37/51 26/57 33/57 30 0 0 0 0 0
*Wind Advisory in effect until 6a.m. CDT Friday.*
Tonight...Mostly Cloudy, Windy, & Colder with patchy drizzle or light rain mainly before midnight. Slow clearing after midnight. Low 34. NNW wind 15-25 mph and gusty. Wind chills 15-25 by sunrise.
Friday...Becoming Sunny & Cold. High 49. NNW wind 15-20 mph and gusty early, decreasing to 10-15 mph in the afternoon. Morning wind chills in the 20s.
Friday Night...Clear and Cold w/ an area wide freeze. Low 27. North wind 5-10 mph.
Saturday...Sunny & Warmer. High 55. NE wind 5-10 mph.
Saturday Night...Clear & Cold w/ a Light Freeze. Low 31. Light East wind.
Sunday...Sunny early, Increasing Cloudiness during the day. Warmer. High 58. SE wind 5-10 mph.
Friday 1/21/11 Daily Planner
6a.m.
Weather: Decreasing Cloudiness, Windy, & Cold
Temp: 34
Rain: 0%
Wind: NNW 18
W.C.: 22
9a.m.
Weather: Partly Cloudy & Cold
Temp: 38
Rain: 0%
Wind: NNW 15
W.C.: 27
Noon
Weather: Sunny & Cold
Temp: 43
Rain: 0%
Wind: NNW 12
W.C.: 35
3p.m.
Weather: Sunny
Temp: 49
Rain: 0%
Wind: NNW 10
W.C.: 45
6p.m.
Weather: Clear
Temp: 40
Rain: 0%
Wind: N 7
W.C.: 35
9p.m.
Weather: Clear & Cold
Temp: 34
Rain: 0%
Wind: N 5
W.C.: 32
Drew's 7 Day Outlook
Friday
1-21-11
Low: 34
High: 49
Rain: 0%
Wind: NNW 10-20
W.C.: 20-35
Saturday
1-22-11
Low: 27
High: 55
Rain: 0%
Wind: NE 5-10
W.C.: 25-40
Sunday
1-23-11
Low: 31
High: 58
Rain: <20%
Wind: E 10-15
W.C.: 25-40
Monday
1-24-11
Low: 40
High: 46
Rain: 60%
Wind: ENE/NNW 15-20
W.C.: 30s
Tuesday
1-25-11
High: 47
Rain: 10%
Wind: NNW 10-15
W.C.: 25-35
Wednesday
1-26-11
Low: 31
High: 44
Rain: 10%
Wind: NNW 10-15
W.C.: 25-35
Thursday
1-27-11
Low: 28
High: 45
Rain: 0%
Wind: N 10
W.C.: 25-35
...Marine Forecast...
*Small Craft Advisory in effect until 9a.m. Friday.*
Tonight...North winds 20 to 25 knots becoming 15 to 25 knots after midnight. Seas 3 to 5 feet.
Friday...North winds 15 to 20 knots becoming northeast 5 to 10 knots in the afternoon. Seas 2 to 4 feet subsiding to 2 to 3 feet in the afternoon.
Friday Night...North winds 5 to 10 knots. Seas 2 feet.
Saturday...North winds 5 to 10 knots. Seas 1 to 2 feet.
Saturday Night...Southeast winds 5 to 10 knots becoming around 10 knots after midnight. Seas 1 to 2 feet building to 2 to 3 feet after midnight.
Sunday...Southeast winds 10 to 15 knots. Seas 3 feet. A slight chance of showers in the afternoon.
...Tide Data...
Friday Tides @ Calcasieu Pass
Low: 9:31a.m. 10:09p.m.
High: 1:49a.m. 4:52p.m.
...Toledo Bend Pool Level...
163.91'
...Lake Charles Climate Summary...
Thursday, January 20, 2011
Low: 47
Normal Low: 41
Record Low: 19-1940
High: 68
Normal High: 60
Record High: 85-1914
Rainfall
Today: 0.02"
Month to Date: 3.02"
Normal Month to Date: 3.67"
Year to Date: 3.02"
Normal Year to Date: 3.67"
Record: 2.22"- 1993
Sensible Weather Observed:
Fog
Rain
One Year Ago (2010)
Low: 62
High: 73
Rain: 0.12"
5 Years Ago (2006)
Low: 59
High: 73
Rain: Trace
10 Years Ago (2001)
Low: 29
High: 47
Rain: 0.00"
Sunrise Friday: 7:08a.m.
Sunset Friday: 5:40p.m.
Hunting Times:
6:38a.m.-6:10p.m.
...Lunar Table...
Last Quarter- Wednesday January 26
New Moon- Thursday February 3
First Quarter- Friday February 11
Full Moon- Friday February 18
Have a great Friday & God Bless!
-DM-
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