Interesting New Orleans Wx Discussion

[Opal storm]

I'm looking at some of the forecasts for Christmas and it looks like it will be warm and rainy here,maybe even thunderstorms on Christmas Eve.

[southerngale]

The good GFS giveth and the bad GFS taketh away.

Ain't that the truth! That should be in the title of these southern snow-wishing threads.

[cctxhurricanewatcher]

The good GFS giveth and the bad GFS taketh away.

The GFS did the same thing with our 2004 Christmas snow down here.

[Janie2006]

The good GFS giveth and the bad GFS taketh away.

Ok, thats really funny!

[Lindaloo]

and of course... the 12z is warmer with less precip. Blah. Story of my life.

That could change tomorrow. Our hurricane saying is "It ain't over til the fat lady sings"

[PTrackerLA]

Not surprised that the models have trended warmer, look for a turn to colder or maybe even warmer as we trend closer. I remember back with the 2004 event the possibility of snow would completely disappear only to reappear with the next model run as we lead up to the event. With all that being said, I feel we'll be left with a cold rain while areas further northward could see a significant snow/ice event. At least it SHOULD get much colder for Christmas which is encouraging.

[Opal storm]

New Orleans still not giving up on the chance for frozen precip.But despite that it sounds like it could be a very wet Christmas along the Gulf coast.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
303 PM CST MON DEC 18 2006

.DISCUSSION...

OVER THE WEEKEND AND INTO EARLY NEXT WEEK ANOTHER PERIOD OF MESSY
WEATHER APPEARS TO BE IN THE OFFING...HOWEVER THE MODELS DIFFER
WITH THE TIMING OF FEATURES. THE GFS HAS BECOME MORE PROGRESSIVE
WITH THE NEXT CLOSED MID/UPPER LEVEL LOW FORECAST TO DEVELOP OVER
THE SOUTHWEST CONUS...WHICH IS NOW FARTHER NORTH THAN PREVIOUS
RUNS...AS MORE ENERGY DIVES SOUTH ACROSS THE WESTERN U.S. LATE IN
THE WORK WEEK. THIS FEATURE THEN EJECTS EAST NORTHEAST ACROSS TEXAS AND
AND THE LOWER MISSISSIPPI VALLEY OVER THE WEEKEND WITH MORE ENERGY
MOVING THROUGH THE BACKSIDE OF THE UPPER TROUGH FORMING ANOTHER
CLOSED LOW OVER THE LOWER/MID MISSISSIPPI VALLEY BY CHRISTMAS. THE
ECMWF IS CONSIDERABLY SLOWER. AS THE SYSTEM OVER THE WEEKEND EJECTS
NORTHEAST...CYCLOGENISIS IS ADVERTISED BY THE GFS TO TAKE PLACE
OVER THE NORTHWEST GULF WITH THE SURFACE LOW MOVING EAST NEAR THE
LOUISIANA COAST SUNDAY. A SOMEWHAT SLOWER SOLUTION THAN THAT OF
THE GFS WILL BE FOLLOWED FOR THIS PACKAGE. ALTHOUGH IT IS STILL
EARLY AND TIMING COULD BE AN ISSUE...THE GFS FORECASTS ABUNDANT
MOISTURE WITH THIS SYSTEM AND LOCALLY HEAVY RAIN COULD BE A THREAT
SUNDAY. THICKNESSES ARE FORECAST TO DROP SHARPLY CHRISTMAS
NIGHT...MONDAY NIGHT...WITH THE POSSIBILITY OF SOME FROZEN
PRECIPITATION AFFECTING PARTS OF THE GULF COAST STATES BEFORE THE
SYSTEM MOVES OFF TO THE EAST.

&

[Opal storm]

From the Mobile AFD today:

.LONG TERM...STILL A LOT OF MODEL SLOP WITH THE FRONT STALLING EARLY
IN THE WEEKEND AND WILL THE AIRMASS WILL BE COLD ENOUGH OVER ANY PART
OF THE FA TO SEE ANY FREEZING/FROZEN PRECIP.

Very brief long term forecast,I guess they will wait and see what the models do before getting too detailed on this weekend's forecast.

[BreinLa]

Hey PT Rob says maybe some frozen precip

[Janie2006]

From the Mobile AFD today:

.LONG TERM...STILL A LOT OF MODEL SLOP WITH THE FRONT STALLING EARLY
IN THE WEEKEND AND WILL THE AIRMASS WILL BE COLD ENOUGH OVER ANY PART
OF THE FA TO SEE ANY FREEZING/FROZEN PRECIP.

Very brief long term forecast,I guess they will wait and see what the models do before getting too detailed on this weekend's forecast.

KMOB is just joining in on the annual holiday teasing event.

[Opal storm]

Mobile still mentioning "freezing/frozen precip" in the AFD.IMO I think temps will be too warm.

.LONG TERM [SUNDAY THROUGH WEDNESDAY]...THIS LOW WILL TRACK TO THE
NORTHEAST TOWARD THE FLORIDA PANHANDLE/BIG BEND REGION SUNDAY AND
SUNDAY NIGHT...INCREASING RAIN CHANCE ONCE AGAIN. IN THE WAKE OF
THIS LOW PRESSURE...THERE REMAINS A SLIGHT CHANCE FOR PRECIPITATION
TO CONTINUE CHRISTMAS DAY INTO EARLY TUESDAY WITH WRAP AROUND
MOISTURE PRESENT...AND A SERIES OF UPPER AIR DISTURBANCES MOVE EAST
ACROSS THE REGION IN THE COOLER AND MORE STABLE SIDE OF THE SYSTEM.
STILL DEBATING WHETHER OR NOT THE AIRMASS WILL BE COLD ENOUGH OVER
ANY PART OF THE FCST AREA TO SEE ANY FREEZING/FROZEN PRECIP
CHRISTMAS DAY NIGHT. TEMPERATURES WILL CONTINUE TO DROP BELOW NORMAL
LATE IN THE FORECAST PERIOD. /22

[southerngale]

Don't fall for it, Opal Storm. Don't fall for it.

[Janie2006]

It appears that the NWS forecasters are still having problems ironing out the forecast for Christmas. This afternoon's AFD from New Orleans continues to indicate uncertainty:

AN EMBEDDED SHORT WAVE AHEAD OF THE NEXT SYSTEM MAY HAVE A SLIGHT
WEST FLOW BEHIND TO PUSH THE MOISTURE AXIS EAST FRIDAY INTO FRIDAY
NIGHT. FRONTAL WILL LIKELY PUSH THROUGH THE FRIDAY AND STALL OVER
THE COASTAL WATERS/NORTH GULF. ANOTHER STRONG UPPER LEVEL LOW WILL
DIVE ACROSS NORTHERN MEXICO EARLY SATURDAY AND DEVELOP A SURFACE
LOW ALONG THE OLD BOUNDARY/NORTH GULF. RAIN CHANCES WILL HIGHER
FOR SOUTH ZONES THAN NORTH ZONES SUNDAY INTO SUNDAY NIGHT. UPPER
LEVEL TROUGH/SYSTEM AND SURFACE LOW WILL MOVE EAST OVER AREA EARLY MONDAY.
HOWEVER...ANOTHER SHORT WAVE IN THE NORTHERN STREAM IS EXPECTED TO
QUICKLY DIVE SOUTH RIGHT BEHIND THE PREV SYSTEM. THIS SYSTEM FOR
MONDAY NIGHT IS COLD CORE...ABOUT -30C OVER SOUTH MISSISSIPPI
MONDAY NIGHT. WRAPAROUND MOISTURE FROM PREVIOUS MAY OR MAY NOT BE
ENOUGH TO SQUEEZE OUT MIXED PRECIPITATION ACROSS EXTREME SOUTH
CENTRAL MISSISSIPPI AND COASTAL MISSISSIPPI. WE WILL KEEP IT DRY
FOR NOW FOR CHRISTMAS NIGHT. A DRY FORECAST IS EXPECTED AFTER
TUESDAY AND WEDNESDAY.

The same uncertainty seems to be in place at KJAN (Jackson) and KMOB (Mobile). A portion of Mobile's afternoon AFD has been posted in the thread.

I don't think frozen precip is a great possibility in these parts. However, as of the moment, the slight potential still exists. The dreaded fat lady has not yet sung....even if she is warming up offstage.

[Opal storm]

They're just teasing us now.

Mobile 4:45am AFD

STILL MONITORING AS TO WHETHER OR NOT THE
AIRMASS WILL BE COLD ENOUGH OVER ANY PART OF THE FCST AREA TO SEE
ANY FREEZING/FROZEN PRECIP CHRISTMAS DAY NIGHT OR EARLY NEXT
TUESDAY.

[rsdoug1981]

I guess everyone's been too busy with the cruddy weather to post the afternoon teaser from the New Orleans NWS.

ANOTHER SYSTEM DIVES SOUTHEAST TO THE NORTH GULF CHRISTMAS NIGHT. IT HAS MOISTURE...RIGHT THICKNESS VALUES...SOUNDING AT 06Z ACROSS NORTH ZONES SUPPORT SNOW GRAINS/SNOW MIX FOR CHRISTMAS NIGHT JUST NORTH AND NORTHWEST ZONES...WILL ADDRESS IN LATER FORECAST PACKAGES.

The Jackson NWS has taken any mention of flurries out of it's forecast.

[Opal storm]

New Orleans AFD mention what GFS is showing.

GFS CONTINUE TO HINT AT A WINTRY MIX PRECIP CHRISTMAS NIGHT JUST
NORTH OF FORECAST AREA OR POSSIBLY NORTHERN ZONES WHILE ETA AND ECMWF
MODELS ARE NOT AS STRONG AND AS FAR SOUTH WITH THIS FEATURE. AFTER THE
GULF LOW AND ASSOCIATED SHORT WAVE PUSH EASTWARD...SOME WRAPAROUND
MOISTURE WILL BE PICK UP BY THE NEXT SYSTEM ACROSS MISSISSIPPI.
THE NEXT SHORT WAVE DEVELOPS INTO THE NEAR A LONG WAVE FROM HUDSON
TO LOWER MISSISSIPPI VALLEY CHRISTMAS. AT 5H...THE ASSOCIATED COLD
CORE OF -30 TO -34C TRACKS ACROSS NORTHWEST LOUISIANA 00Z TUESDAY
TO SOUTH MISSISSIPPI BY 06Z ACCORDING TO GFS. GFS MODEL SOUNDING
AT MCCOMB SHOWS A SATURATED LAYER FROM 950 TO 850MB AROUND -3 TO
-5C WHILE WARM LAYER...SLIGHTLY ABOVE 0C...RESIDED FROM THE
SURFACE TO 1500 FEET. PRECIP FALLING THROUGH THIS COLUMN WITH
LOWER WET BULB TEMP BELOW FREEZING AT NIGHT. IN ADDITION...THICKNESS
LAYER 5400M THICKNESS LINES WAS JUST SOUTH OF NEW
ORLEANS...HOWEVER ATM MUCH DRYER FARTHER SOUTH. MORE SHALLOW
THICKNESS OF 1000 TO 700MB SHOWED VALUES 2790 TO 2800 METER AROUND
06Z TUESDAY ACROSS EXTREME SOUTH MISSISSIPPI AND NORTHERN SECTIONS
OF EAST CENTRAL. QPF FIELDS SHOWS A 0.10 TO 0.15 INCH JUST NORTH
OF FORECAST AREA FROM 00Z TO 06Z TUESDAY. ON THE OTHER HAND...FLOW
IS NORTHWEST FROM THE SURFACE TO 500MB.MEANING...IF ANY PRECIP
OCCUR...AMOUNTS WILL BE LIGHT. VERY SHARP TROUGH WILL LIFT EAST
TUESDAY MORNING. ECMWF THICKNESS VALUES ARE NOT AS LOW AND PLACES
5400M LINE ACROSS CENTRAL MISSISSIPPI. WILL MAINTAIN 14 PERCENT
POPS FOR IN GRIDS AND CHANCE OF RAIN MONDAY NIGHT.

[AL Chili Pepper]

It's looking like at least SOMEBODY in the mid-south will be seeing some flurries over the long weekend. This could be fun to watch.

[Opal storm]

New Orleans mentions the possibility for a few snowflakes or sleet pellets Christmas night as moisture wraps around the back side of the low.

3:59 am AFD

.DISCUSSION...AFTER A BRIEF RESPITE TODAY FROM THE RAIN AND CLOUDY SKIES...
CLOUDS AND RAIN WILL MAKE A QUICK RETURN TO THE FORECAST AREA LATER
TONIGHT AND SUNDAY. PLAN TO LEAN TOWARD THE GFS SOLUTION OF BRINGING
THE RAIN BACK INTO THE PICTURE SOONER AS THIS MODEL HAS BEEN THE
MOST CONSISTENT WITH THIS NEXT SYSTEM. WATER VAPOR IMAGERY SHOWS
THE SOUTHERN STREAM CLOSED MID/UPPER LOW OVER NORTHERN MEXICO
EARLY THIS MORNING. THIS SYSTEM IS FORECAST TO EJECT EASTWARD
ACROSS SOUTHERN TEXAS LATER TONIGHT AND SUNDAY AND ACROSS THE
LOWER MISSISSIPPI VALLEY SUNDAY. AS THIS OCCURS...CYCLOGENESIS IS
FORECAST TO TAKE PLACE OVER THE WESTERN GULF TONIGHT WITH THE
SURFACE LOW TRACKING EAST NORTHEAST NEAR THE SOUTHEAST LOUISIANA
AND MISSISSIPPI COASTS LATE SUNDAY AND SUNDAY NIGHT. WIDESPREAD
RAINFALL IS EXPECTED WITH THE APPROACH OF THIS SYSTEM BEGINNING
LATE TONIGHT OVER THE FAR SOUTHWESTERN SECTIONS OF THE FORECAST
AREA AND SPREADING EAST AND NORTH ACROSS THE REGION SUNDAY AND
SUNDAY NIGHT. LOCALLY HEAVY RAINFALL WILL AGAIN BE POSSIBLE WITH
THIS SYSTEM AND WITH THE GROUND ALREADY BEING SATURATED THE
ADDITIONAL RAINFALL WILL BRING WITH IT THE POSSIBILITY OF
FLOODING. THE ISSUANCE OF A FLOOD WATCH MAY BE REQUIRED IN A
SUBSEQUENT FORECAST PACKAGE. AFTER THIS UPPER FEATURE MOVES OFF TO
THE NORTHEAST...A DIGGING NORTHERN STREAM UPPER TROUGH/LOW WILL
SWING ACROSS THE LOWER MISSISSIPPI VALLEY CHRISTMAS DAY AND MONDAY
NIGHT WITH THICKNESSES FORECAST TO LOWER SIGNIFICANTLY. IT APPEARS
THAT MOST OF THE SUBSTANTIAL MOISTURE WILL HAVE SHIFTED EAST OF
THE AREA BEFORE THICKNESSES LOWER ENOUGH FOR ANY FROZEN
PRECIPITATION...HOWEVER A FEW SNOWFLAKES OR ICE PELLETS MAY BE
POSSIBLE ACROSS NORTHERN SECTIONS OF THE FORECAST AREA CLOSER TO
THE CENTER OF THE PASSING UPPER LOW MONDAY NIGHT. AT THIS TIME WE
WILL ONLY MENTION A SMALL CHANCE FOR LIGHT RAIN MONDAY EVENING
ACROSS NORTHERN SECTIONS OF THE FORECAST AREA.

[Janie2006]

And that's the bugaboo, Opal. At this point I think the moisture will have moved off to the east of New Orleans and Mobile before the atmosphere becomes cold enough to support winter precip. On the other hand, we're still a good 24 hours out, so let's see what happens!

[MGC]

The 0Z 24 Dec GFS and NAM at 48 hours both have the 850mb 0C and the 540 thickness south of the Miss Gulf Coast with some decent wrap around moisture. Ya gotta think we might get some white stuff out of this. Sure would be nice. Hopefully the low that is currently developing off the Texas cost will be stonger than forecast and track south of the mouth of the Mississippi River keeping us in the cold air. A stonger low should advect a little more colder air into the region hopefully allowing a bit of snow...MGC