Deep South Winterwx Discussion 2015-2016

#4521 Postby **northjaxpro** » Fri Jan 24, 2014 5:19 pm

The WFO in Tallahassee has finally come around for now to introduce possible wintry precip late Tuesday into early Wednesday in their late afternoon AFD:

The main story is the potential for wintry precip on Tuesday
night. Both the 24/00z ECMWF and 24/12z GFS agree on the large
scale pattern, featuring a positively tilted upper level trough, a
weak area of low pressure in the Gulf, and an Arctic airmass.
However, as with almost all cases of wintry weather in this part
of the country, the fine details are what really make the
difference, and there are HUGE differences in the vertical
temperature profile between the GFS and ECMWF. One can see this
just by examining the 850 mb temperatures on 12z Wednesday, which
range from -5C on the 24/00z ECMWF to +4C on the 24/12z GFS for
Tallahassee. The GFS forecast soundings in BUFKIT look more like
freezing rain soundings for areas that can manage to get a surface
temp below freezing. Meanwhile, the ECMWF looks more like snow. At
this point still being several days away, there are way too many
uncertainties with this potential unusual event to be too
specific, other than to say that there is a chance of a mix of
precip types across a large part of the area. Behind this system,
another cold airmass appears likely

Jag95 · #4522 Postby **Jag95** » Fri Jan 24, 2014 5:21 pm

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE MOBILE AL
356 PM CST FRI JAN 24 2014

...A WINTER WEATHER ADVISORY IS NOW IN EFFECT FOR PORTIONS OF
INTERIOR SOUTHEAST MISSISSIPPI AND A SMALL PORTION OF COASTAL ALABAMA
THROUGH 9 PM CST THIS EVENING...

.TEMPERATURES HAVE STRUGGLED TO WARM DURING THE DAY ON FRIDAY...AND
HAVE ALREADY DROPPED TO BELOW 32 DEGREES OVER PARTS OF THE REGION...
ESPECIALLY FROM MOBILE COUNTY ALABAMA WESTWARD THROUGH STONE...
GEORGE...PERRY AND GREENE COUNTIES OF SOUTHEAST MISSISSIPPI. ANOTHER
ROUND OF PRECIPITATION IS EXPECTED TO MOVE INTO THE ADVISED AREA FROM
THE WEST THROUGH 9 PM THIS EVENING...WITH A MIXTURE OF LIGHT SLEET
AND SNOW POSSIBLE. ALTHOUGH NO WIDESPREAD TRAVEL PROBLEMS ARE ANTICIPATED...
WITH TEMPERATURES ALREADY BELOW FREEZING SOME SPOTTY MINOR ACCUMULATIONS
ON BRIDGES AND OVERPASSES COULD OCCUR THIS EVENING.

For next week: :cheesy:

Monday Night: A slight chance of rain before midnight, then a slight chance of snow, freezing rain, and sleet. Mostly cloudy, with a low around 29. Blustery, with a north wind 15 to 20 mph. Chance of precipitation is 20%.

Tuesday: A slight chance of snow and sleet. Mostly cloudy, with a high near 39. North wind around 15 mph, with gusts as high as 20 mph. Chance of precipitation is 20%.

Tuesday Night: A 20 percent chance of snow. Mostly cloudy, with a low around 24. North wind 10 to 15 mph.

SeGaBob · #4523 Postby **SeGaBob** » Fri Jan 24, 2014 6:31 pm

My area is has been placed in a 20% chance of snow by the NWS in Charleston, SC Tuesday Night/Wednesday early afternoon... hopefully the trend will go even higher.

Also have 18z models been run yet?

SeGaBob · #4524 Postby **SeGaBob** » Sat Jan 25, 2014 9:37 am

Any more model runs? Our NWS says the models have shifted further east...

#4525 Postby **northjaxpro** » Sat Jan 25, 2014 10:12 am

Awaiting the 12Z runs. Remember, the EURO runs severely underestimated the shortwave energy which just impacted Texas and Louisiana. The energy was supposed to get suppressed southward, and instead pieces of the shortwave ejected much farther eastward that what the models showed. Freezing rain and sleet was reported as far east as Mobile, AL and portions of the western Florida panhandle. Sleet fell all the way east here in Jax during the wee hours this morning.

My point here: I would wait until Monday to see what the models will layout for this potential event. CMC model performed very well with the Texas-Louisiana winter event, so I would not discount that model or NAM as well for this potential event coming by Tuesday-Wednesday of next week.

SeGaBob · #4526 Postby **SeGaBob** » Sat Jan 25, 2014 10:26 am

Thanks for your input...

I hope this is just a case of models losing it and then bringing it back. Can you post some 12Z runs when they become available?

CYCLONE MIKE · #4527 Postby **CYCLONE MIKE** » Sat Jan 25, 2014 10:29 am

Can't post it but the 12z Nam looks just as good maybe a bit better for se tx all along the gulf coast. LA looks like it could get hit pretty hard with an ice storm.

#4528 Postby **northjaxpro** » Sat Jan 25, 2014 10:38 am

Yeah, I just found the NAM 12Z. Very impressive overrunning precip scenario NAM is showing here all along the Gulf Coast region. It shows rather significant precip just along and south of the Louisiana coast. Man, if this verified, this would be quite an event for sure.

But, remember, NAM is a pretty good model for these type of synoptic winter-time systems. I definitely see this as plausible indeed.

SeGaBob · #4529 Postby **SeGaBob** » Sat Jan 25, 2014 10:41 am

Here's one i found of the 12Z NAM.. not sure if it's a good one or not though.

http://www.hpc.ncep.noaa.gov/hpcaq/namrefl/nam_sim_refl.php?cycle=12

CYCLONE MIKE · #4530 Postby **CYCLONE MIKE** » Sat Jan 25, 2014 10:43 am

And it actually starts at hr 72 here. Three days away but obviously a lot can still change. Would like to see the gfs back to showing more before I get too excited. But as you said potential is there for sure.

#4531 Postby **northjaxpro** » Sat Jan 25, 2014 11:14 am

6Z GFS. For now, GFS is back to showing potential snow across northern Florida and along the immediate SE Atlantic coast region, but keeps the moisture suppressed south in the GOM away from the coast.

Will watch to see if GFS will trend as time progresses more un line with EURO, CMC and NAM in having moisture further north along and inland of the Gulf Coast

timmeister · #4532 Postby **timmeister** » Sat Jan 25, 2014 11:19 am

Excerpt from the Area Forecast Discussion from the NWS in Jackson MS:

MONDAY THROUGH WEDNESDAY NIGHT...ALL GUIDANCE IS IN STRONG AGREEMENT
THAT FRIGID ARCTIC AIR WILL MAKE A RETURN TO THE ARKLAMISS FOR THE
EARLY TO MID WEEK...AND THERE ARE GROWING INDICATIONS THAT THE RISK
FOR AT LEAST LIGHT WINTRY PRECIPITATION IS ON THE INCREASE FOR AT
LEAST AREAS ALONG AND SOUTH OF THE I-20 CORRIDOR.

AS HAS BEEN THE CASE WITH MOST COLD FRONTS THIS WINTER SEASON...
EXPECT AN EARLY MORNING ARRIVAL FOR THE FRONT MONDAY. THIS WILL
MAKE TEMPERATURES TRICKY GIVEN THE STRONG MIXING THAT WILL TEND TO
NEGATE THE SURFACE COLD ADVECTION SOME INITIALLY IN THE
MORNING...ALTHOUGH THERE SHOULD BE MORE CLOUD POTENTIAL AND EVEN A
FEW SHOWERS ALONG/AHEAD OF THE FRONTTHIS TIME AROUND WHICH COULD
HASTEN THE COOLING TREND. FALLING TEMPERATURES ARE EXPECTED FOR THE
MOST PART MONDAY AFTERNOON WITH STRONGER COLD ADVECTION EXPECTED
MONDAY NIGHT THAT WILL LIKELY SEND TEMPERATURES INTO THE TEENS ALONG
THE HIGHWAY 82 CORRIDOR. THERE MAY BE GREATER FUNNELING OF THE COLD
AIR THROUGH THE UPPER DELTA REGION AND HAVE CUT TEMPERATURES THERE A
BIT. ON THE OTHER HAND...THICKER CLOUD COVER OVER SOUTHERN PORTIONS
OF THE ARKLAMISS COULD KEEP TEMPERATURES UP A LITTLE AND HAVE RAISED
GUIDANCE VALUES THERE.

A STRONG BAROCLINIC ZONE WILL SET UP ACROSS THE GULF COAST STATES AS
THE FRONT CONTINUES TO PUSH SOUTH. WHILE THE GFS/ECMWF ARE BEARISH
WITH PRECIPITATION POTENTIAL MONDAY NIGHT AND TUESDAY...A NUMBER OF
MODELS (GEM/GEFS/SREF/NAM) INDICATE JUST ENOUGH BACKING OF THE MID
LEVEL FLOW/ISENTROPIC UPGLIDE WILL HELP TO BREAK OUT PRECIPITATION
ACROSS THE REGION. WITH CONTINUED COLD ADVECTION...THIS PRECIPITATION
WOULD LIKELY BE IN THE FORM OF SNOW...ALTHOUGH THE NAM SHOWS A
PRONOUNCED WARM LAYER ALOFT THAT WOULD INCREASE THE ODDS FOR
FREEZING RAIN AND SLEET MONDAY NIGHT. ALL GUIDANCE INDICATE THE
COLUMN WOULD BE COLD ENOUGH FOR ALL SNOW TUESDAY...AND THE GEM AND
SEVERAL GEFS/SREF MEMBERS ACTUALLY INDICATE THE POTENTIAL FOR A FEW
INCHES OF SNOW. BUT GIVEN THAT THE BULK OF GUIDANCE IS ON THE DRY
SIDE...WILL KEEP POPS LOW FOR NOW.

WILL NEED TO CLOSELY WATCH FOR MORE DIGGING OF THE LONGWAVE TROUGH
AND GREATER ENERGY ROUNDING ITS BASE THAT COULD INCREASE LIFT OVER
THE AREA. THE 06Z GFS INDICATES THAT HIGH PRECIPITABLE WATER > 1 INCH
WILL BE NEAR THE GULF COAST AND MASS FIELDS SUGGEST IT ONLY TAKE
SLIGHT PERTURBATIONS TO MAKE A BIG DIFFERENCE IN QPF AS WAS THE CASE
IN THE PAST EVENT OVER LA/SRN MS.

SeGaBob · #4533 Postby **SeGaBob** » Sat Jan 25, 2014 11:28 am

northjaxpro wrote:6Z GFS. For now, GFS is back to showing potential snow across northern Florida and along the immediate SE Atlantic coast region, but keeps the moisture suppressed south in the GOM away from the coast.

Will watch to see if GFS will trend as time progresses more un line with EURO, CMC and NAM in having moisture further north along and inland of the Gulf Coast

Which model solution would give the most snow in our areas? Not sure if you're familiar with my area on the map though.

#4534 Postby **northjaxpro** » Sat Jan 25, 2014 11:36 am

Well SeGaBob, root for the NAM verifying or CMC to give the Gulf Coast region and extreme SE U.S. for the potential of giving the most snow. Looking at those particular runs, if they somehow come close to verifying, the potential of a few inches of snow could fall on a wider area with the amount of isentropic lift shown on the above models.

SeGaBob · #4535 Postby **SeGaBob** » Sat Jan 25, 2014 11:40 am

Thanks...any snow at all is a big deal here.(and probably where you are too.)

#4536 Postby **BigB0882** » Sat Jan 25, 2014 12:07 pm

I am definitely rooting for the NAM. We are 72 hours out from the start of the event. That is pretty close. With the NAM it usually does well in these events although in this last event it really didn't see all the precip we ended up with here in SELA. However, I don't think any models did. The GFS is SO close to backing up the NAM, just too far off shore. Maybe it will come around.

SeGaBob · #4537 Postby **SeGaBob** » Sat Jan 25, 2014 12:41 pm

12Z GFS is very disappointing... I hope 18Z is better.

#4538 Postby **MississippiWx** » Sat Jan 25, 2014 12:58 pm

Not as disappointing as the 12z CMC which was really the only model hanging on to snow/winter precip. It is now dry and suppressed like the GFS.

SeGaBob · #4539 Postby **SeGaBob** » Sat Jan 25, 2014 1:06 pm

There is still the NAM but it looks overdone compared to the others...but it is still 3 days away though.

http://coolwx.com/cgi-bin/getptype.cgi?region=us&model=nam&run=12&fhr=29&field=ptype

#4540 Postby **BigB0882** » Sat Jan 25, 2014 1:09 pm

Does anyone know what the EURO is showing?

It seems we have the NAM and CMC (normally I ignore CMC but it seemed to do well on the last event from what I heard) saying the Gulf Coast is a prime spot and up to the East.

Then we have GFS saying it is a south central TX event and then keeps it too far off shore for the rest of us. From the sounds of it the GEFS (I assume this is not the same as GFS) is in between NAM and GFS but closer to the GFS.

Someone in the TX thread said models were coming into agreement for them over there but I am trying to figure out what other models are showing what the GFS is.

The EURO seems to be the only model no one has mentioned.

ETA: CMC has switched to GFS. Didn't realize. I guess we are stuck rooting for the NAM.

Deep South Winterwx Discussion 2015-2016

Re: Deep South Winterwx Discussion

Re: Deep South Winterwx Discussion

Re: Deep South Winterwx Discussion

Re: Deep South Winterwx Discussion

Re:

Re: Deep South Winterwx Discussion

Who is online