Tuesday, February 9, 2010

The Return of Winter...Active Pattern Continues...Frozen Precip Later This Week???

Monday, February 8, 2010

WHO DAT! WHO DAT! The Saints Miracle Season is Complete...Saints 31 Colts 17...The New Orleans Saints won Super Bowl XLIV to claim their first ever NFL Title and the first ever professional world championship in professional sports for the city of New Orleans and the great state of Louisiana! We are so proud of you, boys! Bless you, boys! Congratulations!

SW Louisiana Forecast Discussion...February 2010 has been a chilly one so far, as has the winter of 2009-2010 overall. The trend will continue this week, and then some. After a mild day with highs reaching the lower 60s with mostly cloudy skies, a strong cold front is slicing through the area tonight. A line of showers and thunderstorms marks this boundary with some lightning and strong winds, but no severe weather has occurred or is expected. Rain chances are quickly tapering off, and will be almost non-existent by 2-3a.m. Moisture levels increased throughout the day, and a weak warm front lifted NE through the forecast area through the day. This created the instability and lift necessary to produce the expected rainfall. The front is moving through very quickly, and this has helped to limit rainfall amounts to an inch or less across the area. A sharp temperature gradient exists across our great state with 60s out ahead of the boundary over Acadiana and into SE Louisiana, while temperatures have dropped into the 30s in NW Louisiana. Temperatures are beginning to drop here in Lake Charles, as CAA takes over in the wake of the Arctic front. Tumbling temperatures will be the name of the game in the wake of the front, and we will be fiercely reminded that it is still winter. Temperatures will fall into the upper 30s to lower 40s across the forecast area overnight. Some intermittent light rain or drizzle can't be ruled out behind the front, but for the most part the significant rainfall is over for now across the majority of the forecast area. Winds will increase as well behind the front with NNW winds over 25 mph at times after midnight. A wind chill factor will come into play as well by Tuesday morning with readings down into the 20s at times.

Tuesday will be a dry day, but clouds will be hesitant to vacate the region at first. Some clearing will be noted during the day, but it may take much of the day for skies to completely clear with a large low cloud deck hanging back over Texas. Even if we end up with more sunshine than expected, it will be a very cold day Tuesday. CAA will continue as a large high who's source region is from Canada builds down into the region. Don't expect temperatures to get out of the 40s. This is much closer to the normal low than the normal high. The actual high will occur at midnight in the mid 50s, but as the CAA strengthens after midnight temperatures will begin a more rapid free fall until after sunrise. Only a slow rise is expected with temperatures topping out between 45 and 48. Winds will remain quite gusty through the morning hours as the presence of a strong pressure gradient exists. Winds will slack off in the afternoon as the high nudges into the area. Skies clear Tuesday evening, and this will set the stage for an area wide freeze Tuesday night. Temperatures should fall into the mid 20s across the northern portion of the forecast area, and be tempered upwards toward the coast with readings right around freezing. Please be sure to take the necessary freeze precautions. (pets and plants). Pipes shouldn't be an issue this time around. This air mass isn't quite as cold as the one from a month ago, but there is also a significant snow pack down into the Ozarks which will limit air mass modification as the cold air is transported into the area. Other than it being cold, quiet weather is in store for the Tuesday night period. If you are going to New Orleans to celebrate with the Saints in the victory parade, bring a coat. It should be in the mid 40s at parade time with temperatures falling into the upper 30s before it's over. Cold and dry weather is expected for Wednesday as well, but the benign weather will once again be short-lived as the ever progressive pattern of the winter of 2009-2010 continues to rear its ugly head. The day should start Sunny with the freezing temperatures across the area, but clouds will increase during the day as our next system approaches. Highs should top out in the mid to upper 40s, well below normal once again. There is some question as to how fast we'll cloud back up again, and this will dictate how warm we get (relatively speaking). If it starts clouding up sooner than expected at this time, then highs will be in the lower end of the 40s, but if the clouds are delayed til later in the day then 50 is feasible. For now, I'll split the difference, but either it is sure to be cold. Winds won't be as much of an issue, but there will be some to factor into the equation as there will be a pressure discrepancy with the approach of the next system.

By Wednesday night, clouds increase in earnest as the next storm system begins to impinge upon the forecast area. This system (at least part of it) is currently evident on satellite imagery off the coast of the Pacific NW. This storm will continue the continuous parade of storms, and is diving SE tonight. It will move quickly via a strong Jet Stream through the Rockies and Great Plains, and round the base of a digging trough and across Texas and into our area the second half of the work week. The Subtropical Jet Stream will remain active over the area, and as the Pacific system moves our way, the same song and dance that we've seen so many times this winter will occur once again. Another The system will engender another Gulf low, and its eventual track remains to be seen. Moisture will be drawn Northward and as another cut off upper level low develops overrunning will prevail underneath the cold air at the surface. The orientation of the low will not allow for any return flow, therefore, the cold air will remain in place. Wednesday night minimums will be near freezing. This is where a whole degree of uncertainty comes in. Rain chances will return to the forecast, but the more widespread rain should hold off until Thursday during the day. However, there will be enough vertical ascent Wednesday night for rain to develop. The surface temperatures Wednesday night/Thursday morning could be cold enough to be supportive of frozen precipitation. The atmospheric profile suggests that if it does occur, it would be in the form of freezing rain and/or sleet. There is a certain degree of complexity with this forecast, and forecasting winter weather is challenging to say the least. I feel as though models are a few degrees too warm, and would concur that the sleet or freezing rain possibilities may come to fruition. Snow appears out of the question at this time for this time frame at least here along I-10. North Louisiana looks to possibly see some very significant snow with this next storm. Overrunning will continue to strengthen through the night, thus precipitation chances will reach the likely category by Thursday morning. Another reason why I believe some frozen precip will occur in this time frame is because of wet bulbing or evaporative cooling. The air mass should be dry enough initially that as precip begins, it will evaporate thus cooling the air column a few degrees while at the same time increasing boundary layer moisture.

Rain is inevitable for Thursday as the Gulf low intensifies and tracks Eastward. It's ultimate track will determine what kind of weather we see. The current track would favor the significant snow threat for North Louisiana, while it leaves our area on the fence as far as seeing any wintry precip. Rain could be heavy at times with an additional 1-2" of rain expected. Any sleet or freezing rain early Thursday morning will change over to all rain by mid-morning. It is too early to suggest how much if any ice would accumulate. I'll take another stab at this issue tomorrow. No severe weather is expected, but precipitation will likely cover the entire state by this time. Temperatures will be hard pressed to make it to 40 degrees on Thursday. A low tracking closer to the coast would decrease any winter weather threat initially as a slug of warmer air would move into the region, while a low that tracks away from the coast over the Gulf would increase the threat for winter weather, and also the likelihood of snow. Exactly what track the low takes is uncertain as models diverge on this idea. Perhaps, for now the way to play it is to split the difference, and go for a track that keeps the possibility of frozen precip in the mix, but doesn't make snow likely. Winds will also be an issue as the Gulf low advances and tightens the pressure gradient resulting in winds over 20 mph out of the NE around the circulation of the low. Timing discrepancies exist as well, but the worst of the weather should be over with by late Thursday. However, rain and precip chances will continue into Friday most likely.


A better chance of frozen precipitation could occur Thursday night and Friday morning on the back side of the low. The back side of the low will help pull down even colder air as is usual, and with a snow pack expected to be even further South at that time, even less air mass modification is expected. I am not ready to jump on the idea of snow yet, but one more day of watching the model runs, and I may have to nibble. I certainly will keep the chance for a mixed bag of precipitation in the forecast with the idea that it will be all snow from Alexandria Northward. The rain chance will continue as the surface low departs, and the upper level low continues to approach. It will take until sometime Friday afternoon for all the moisture to leave the area as the ULL is cut off from the main flow. Don't get your expectations up on seeing anything frozen just yet, this is shear speculation, and models have been consistent enough with it since the weekend that you can't ignore it, but I think we'll have a lot better idea come tomorrow when we're in the cold air and we'll see how the air mass behaves. With the clouds and rain temperatures won't change much from Thursday to Thursday night with only about a 4-7 degree diurnal range at best. Thursday night/Friday morning minimums will be kept in the mid 30s at this point, but again if the low tracks in the right position even this will be cold enough for snow. Friday maximums will once again struggle to reach 40, and I will undercut guidance by several degrees. Numerical guidance is completely out to lunch when it comes to high temperatures for this period due to the fact that in that time frame models are skewed towards climatology. All precip, liquid or frozen, or whatever should end Friday afternoon as the upper level low and surface low ushering in drier air just in time for the weekend. Stay tuned! The wind will continue to be pretty stiff as well adding insult to injury. Wind chills will be in the lower to middle 20s much of the day.

This is a very important weekend indeed...It's Mardi Gras and Valentine's Day! Many Mardi Gras festivities kick off Thursday or Friday depending on where you are. Any Thursday activities don't look so good, but by Friday night the weather looks promising just cold. Skies clear Friday night and there will be another area wide freeze heading into Saturday morning as the Arctic air remains firmly entrenched over the area. Again, I will undercut guidance as temperatures are just too warm at this time. Mid 20s are possible as far South as I-10, but for now I will be a bit conservative and forecast upper 20s, similar to Wednesday morning. This active pattern has brought us an incredibly wet winter, but at least for the most part in 2010 so far our weekends have been nice. That will be the case again this weekend with plenty of sunshine expected both Saturday and Sunday. However, the Arctic air isn't going anywhere. Highs on Saturday with full sunshine will only reach the mid 40s. Another freeze is on tap for Saturday night heading into Valentine's Day on Sunday. Bundle up if you are heading out to Mardi Gras festivities. It will be weather for cuddling with your "valentine." A much weaker system embedded in the active STJ will likely help to increase clouds Sunday afternoon, but it should remain dry. There will be some hint of a warm up at that time as well, but temperatures will still be well below normal with highs approaching 50. The end of the forecast period (Lundi Gras) offers another chance of rain, albeit much smaller than the one that awaits us this week. The next embedded short wave should be much weaker, but should certainly generate enough lift and forcing to produce some cold rain. There will a cold front associated with this system as well, and this will keep the cold weather in place through Mardi Gras Day itself next Tuesday. The chance of rain on Monday has the potential to carry over to Mardi Gras, but it looks like the system will be a fast mover, and it'll be out of here in time for the culmination of the 2010 carnival season. Highs on Monday will be in the 40s once again with lows in the 30s. Another shot of frozen precipitation is possible for Northern Louisiana at this time. Mardi Gras is just beyond the scope of the 7 day, but warrants a look for sure at this point. The early prognostication is Mostly Cloudy, Cold, and Windy with a 20% chance of a shower. Highs should be in the mid 40s while lows will be in the mid 30s....brrr! In closing, here's an aside...the 2 heaviest snowfalls in history across SW Lousiana occurred during this week...February 8-14. 22" of snow fell at Lake Charles on February 14-15, 1895 and 5" fell at Lake Charles on February 12-13, 1960. So, don't give up hope, but don't get them up either at this point!


Preliminary Numbers & Zone Forecast:

LCH  40/47  28/48  32/40  40 0 0 0 40 100
LFT   41/48  27/48  31/40  60 0 0 0 30 100
BPT   39/49  30/48  33/41  20 0 0 0 50 100
AEX  36/45  25/44  29/37  30 0 0 0 30 100
POE  37/45  25/45  29/38  20 0 0 0 30 100
ARA  44/48  29/48  34/42  60 0 0 0 30 100


Tonight...Mostly Cloudy, Windy, & Colder with a 40% chance of light rain or drizzle. Low 40. NNW wind 15-25 mph and gusty. Wind chill near 30 by morning.

Tuesday...Mostly Cloudy with some clearing during the day. Cold & Windy. High 48. NNW wind 15-20 mph and gusty, diminishing during the afternoon.

Tuesday Night...Clear and Cold. Low 28. Light North wind.

Wednesday...Sunny early, becoming Partly Cloudy. Continued Cold. High 48. NE wind 5 mph.

Wednesday Night...Cloudy and Cold with rain developing overnight. Rain possibly mixed with or changing to sleet and/or freezing rain towards morning. Low 32. NE wind 10 mph. Chance of precipitation 40%.

Thursday...Cloudy, Cold, & Windy with Rain likely. Rain may start as or be mixed with sleet and/or freezing rain until mid-morning. High 40. NNE wind 15-20 mph and gusty. Chance of precipitation 100%.


Tuesday 2/9/10 Daily Planner

7a.m.

Weather: Mostly Cloudy, Cold
Temp: 40
Chance of Rain: 0%
Wind: NNW 15
Wind Chill: 30

Noon

Weather: Partly to Mostly Cloudy, Cold
Temp: 45
Chance of Rain: 0%
Wind: N 13
Wind Chill: 36

5p.m.

Weather: Mostly Clear, Cold
Temp: 46
Chance of Rain: 0%
Wind: N 12
W.C.: 35


Drew's 7 Day Forecast

Tuesday
2-9-10







Low: 40
High: 47
Precip: 0%
Wind: NNW 15-20
W.C.: 25-35


Wednesday
2-10-10








Low: 28
High: 48
Precip: 0%
Wind: NE 5
W.C.: 25-40


Thursday
2-11-10








Low: 32
High: 40
Precip: 100%
Wind: NNE 15-20
W.C.: 20-25


Friday
2-12-10








Low: 34
High: 38
Precip: 60%
Wind: NNW 15-20
W.C.: 15-25


Saturday
2-13-10









Low: 27
High: 44
Precip: 0%
Wind: N 10
W.C.: 20-30


Sunday
2-14-10
Valentine's Day
 

Low: 29
High: 48
Precip: 0%
Wind: NE 5-10
W.C.: 25-35


Monday
2-15-10
President's Day
Lundi Gras

Low: 35
High: 45
Precip: 40%
Wind: NNE 10-15
W.C.: 25-30


...Marine Forecast...

*Small Craft Advisory.*

Tonight...Southwest winds 15 to 25 knots becoming northwest 20 to 30 knots after midnight. Seas 3 feet building to 5 feet after midnight. Showers and isolated thunderstorms.

Tuesday...North winds 20 to 30 knots diminishing to 15 to 25 knots in the afternoon. Seas 5 feet subsiding to 3 to 4 feet in the afternoon.

Tuesday Night...North winds 15 to 20 knots. Seas 4 to 6 feet.

Wednesday...Northeast winds 10 to 15 knots. Seas 2 to 4 feet.

Wednesday Night...Northeast winds 10 to 15 knots increasing to 15 to 20 knots after midnight. Seas 2 to 3 feet building to 3 to 5 feet after midnight. A slight chance of rain.

Thursday...Northeast winds 15 to 25 knots. Seas 6 to 9 feet. Rain.


Good night and God bless!
-DM-

No comments:

Post a Comment