Tuesday, January 4, 2011
Rainy Morning, Turning Cooler, not Cold...
A weak upper disturbance is triggering an area of showers that will sweep across SE LA/MS before dawn and into midday Wednesday. Cooler and drier air will filter in behind this system, but the real cold air will stay well to our north. With sunshine back for Thurs-Friday, as long as you're dressed for it, the weather will feel great. Another system off the west coast tonight will streak our way by Sunday bringing our next chance for rain. Computer models continue to indicate colder air returning here for next week. Snow lovers stay tuned !
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3 comments:
ARE YOU SAYING IT GOING TO SNOW IF WE DO GET SNOW MAKE SURE IT IS ON A WEEKDAY SO MY NIECE CAN GET OUT OF SCHOOL
Bob
I have been reading about a major cold outbreak in about 12-15 days. Also read this earlier. Should I quit reading these things and getting excited? Thanks
This is from the N.O. NWS afternoon discussion for 1/5/11
LONG TERM...
CUT-OFF LOW WEST OF THE SOUTHERN CALIFORNIA COAST HAS STOPPED
RETROGRADING AND SHOULD BECOMING PROGRESSIVE AS ONE SHORT-WAVE
ROUNDS THE BASE OF THE TROUGH TONIGHT AND THE PIN-WHEEL SYSTEM
STARTS FEELING THE AFFECTS OF STRONG SUB-TROPICAL FLOW ON THE
EQUATOR SIDE OF THE CIRCULATION. MODEL JET PROGS INDICATE
100-120KT JET MAX ON DOWNWIND SIDE OF THE CIRCULATION DEVELOPING
THURSDAY WHICH SHOULD MAINTAIN ABOUT A 40KT SYSTEM SPEED AROUND
30N LATITUDE. THIS WOULD PUT IT IN THE CENTRAL GULF STATES AREA ON
SUNDAY. GFS SHOWS A WELL DEVELOPED NORTH GULF LOW WITH THIS SYSTEM
PASSAGE WHICH KEEPS MUCH OF THE FORECAST AREA IN THE COLD SECTOR
AND MARGINAL CONDITIONS FOR WINTRY PRECIPITATION PROSPECTS MAINLY
IN SOUTHWEST MISSISSIPPI NORTHWARD DURING THE DAY SUNDAY. THE
ECMWF IS FARTHER NORTH WITH SIMILAR FEATURE AND SLOWER...COMING
THROUGH SUNDAY NIGHT. GIVEN THE PERFORMANCE OF ECMWF LATELY...AND
IN COORDINATION WITH KJAN...OPTED TO GO CLOSER TO ECMWF TIMING
WITH A SLIGHT HEDGE TO COMPROMISE ON LOCATION OF SURFACE
LOW...THEREBY LEANING TOWARDS A SLEET AND POSSIBLY FREEZING RAIN
POTENTIAL ONSETTING SUNDAY EVENING INTO THE OVERNIGHT HOURS BEFORE
ENDING MONDAY MORNING. GFS SOUNDINGS ARE MORE SUPPORTIVE OF A MORE
COMPLEX WEATHER PICTURE AT MCCOMB AREA WITH A COLD RAIN
TRANSITIONING TO WET SNOW ON WET-BULB EFFECT...THEN TRANSITIONING
TO SLEET FOR QUITE A WHILE BEFORE WARM LAYER ALOFT LOWERS DUE TO
LATENT HEAT RELEASE TO SHRINK THE SUB-FREEZING LAYER ENOUGH TO
REDUCE TO EITHER A VERY COLD RAIN OR A PERIOD OF FREEZING
RAIN...DEPENDING ON SURFACE TEMPERATURE AT THE TIME OF PRECIP. AT
THIS TIME...SHOWED DOMINANT WEATHER SUNDAY NIGHT TO BE SLEET BUT
THIS IS USUALLY NOT THE CASE...OFTEN WITH SOME TRANSITIONAL
PRECIPITATION INVOLVED DURING THESE DYNAMIC SYSTEM PASSAGES. IN
LOUISIANA AND MISSISSIPPI COASTAL COUNTIES...TEMPERATURE PROFILES
LOOK TO STAY ABOVE FREEZING THE ENTIRE TIME TO PRETTY MUCH
MAINTAIN A COLD RAIN PROCESS THAT MAY BREIFLY TURN OVER TO SLEET
FOR A VERY SHORT DURATION PRIOR TO PRECIPITATION ENDING. MODEL
TRENDS WILL HAVE TO BE WATCHED...PARTICULARLY FOR TIMING AND
DEGREE OF COLDNESS...BUT CAUSATIVE SYSTEM IS CLEARLY TRACKABLE ON
SATELLITE IMAGERY IN EASTERN PACIFIC. AFTER THIS EVENT...MODELS
SHOW SOME STEADY MODIFICATION THROUGH NEXT WEEK AND SEEM TO HAVE
BACKED OFF ON INTENSITY OF ARCTIC AIRMASS INDICATED IN THE DAY7-10
PERIOD...THOUGH PATTERN IS STILL INDICATED AND FAVORED...BUT
INTENSITY OF SURFACE SURGE WAS UNDERCUT BY ABOUT 10MB OVER NW
CANADA LATE NEXT WEEK. MORE ON THIS IN FUTURE DISCUSSIONS. 24/RR
GREG...best analogy I can give you...Who reads and interprets the X-Ray? The doctor or the nurse? Don't quit reading the discussions. Just remember that beyond 3 days the forecasting skill level drops. Beyond 7 days, it's not much better than climatology. Still makes for fun reading !
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