Deep South Winterwx Discussion 2015-2016

[BigB0882]

12 days out, been here before, but maybe this will be the one that actually happens!



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[Jagno]

[quote="BigB0882"]12 days out, been here before, but maybe this will be the one that actually happens!

I've lived here for 50 years and to date I've never seen more than a little over an inch of accumulated snow in real life. This would be Cajun suicide. We can swim, not snow ski!

[BigB0882]

I'm going to be sacrificing chickens for the next 12 days, if this verifies then I will stock up on chickens for many winters to come.

[Stormcenter]

Below is an excerpt from this morning's NWS discussion out of New Orleans.

THU THROUGH FRI...AS THE SYSTEM CONTINUES TO DIG ON THE BACK SIDE OF
THE ELONGATED L/W TROUGH OVER THE CONUS IT WILL CLOSE OFF OVER THE
SRN PLAINS. AT THE SAME TIME WEAK LOW PRESSURE WILL BEGIN TO DEVELOP
IN THE GULF WITH A ACTUAL SFC LOW IN THE ERN GULF SOUTH OF
PENSACOLA. THIS IS WHERE THE PROBLEMS COULD ARISE. THERE WILL BE
COLD AIR IN PLACE...HOW COLD IS A GOOD QUESTION AS THE ECMWF HAS NOW
SHIFTED A LITTLE WARMER AND THE GFS IS MUCH COLDER THAN IT WAS 24
HRS AGO. AS THE SFC LOW DEVELOPS WE WILL START TO SEE MOISTURE WRAP
AROUND AT THE SAME TIME THE SW FLOW ALOFT WILL CONTINUE TO PUMP IN
SOME PACIFIC MOISTURE. BY THU NIGHT AND INTO FRI THE CLOSED LOW OVER
THE SRN PLAINS WILL BEGIN TO PUSH EAST AND MOVE OVER THE LOWER MS
VALLEY. IT AS AT THIS TIME WHEN WE COULD HAVE ENOUGH FORCING TO
DEVELOP SCT TO NUMEROUS SHRA. ALSO THE TRACK OF THE UPPER LOW ALONG
WITH COL LL TEMPS COULD LEAD TO THE POSSIBILITY OF SOME LIGHT FROZEN
PRECIP. WE ARE RIGHT ON THE EDGE OF ALL LIQUID OR SOME MIX AND WITH
THE MDL DISAGREEMENTS I WILL CONTINUE TO HOLD ONTO ALL LIQUID BUT
THIS IS SOMETHING WE NEED TO WATCH AND SOMETHING WE CAN FOCUS MORE
ON AFTER TUE/S SYSTEM.

[Ivanhater]

NWS Mobile/Pensacola still on it as well...very interesting

INCREASINGLY SOUTHWESTERLY FLOW ALOFT DEVELOPS ON WEDNESDAY AS
ANOTHER SIGNIFICANT PIECE OF ENERGY DIVES INTO THE FOUR CORNERS AND
UPPER LEVEL RIDGING OVER THE CARIBBEAN AMPLIFIES. THIS CAUSES THE
COLD FRONT TO STALL OVER THE CENTRAL GULF OF MEXICO BY LATE WED. THE
AFOREMENTIONED ENERGY OVER THE SOUTHWEST STATES IS FORECAST TO BEGIN
MOVING EASTWARD ON THURSDAY...BUT THE GFS AND ECMWF DISAGREE ON HOW
FAST THIS OCCURS. WHAT IS FAIRLY CERTAIN IS THAT ISENTROPIC LIFT WILL
GRADUALLY INCREASE FROM THU MORNING THROUGH FRIDAY AS WARM ADVECTION
MOVES UP AND OVER THE COLD DOME IN PLACE ACROSS OUR FORECAST AREA.
THIS TRANSLATES INTO LIGHT PRECIP DEVELOPING OVER THE NEAR SHORE
WATERS AND COASTAL ZONES BY EARLY THURSDAY AND SPREADING NORTH OVER
THE REGION BY THURSDAY NIGHT INTO FRIDAY. GFS PARTIAL THICKNESSES
CONTINUE TO INDICATE THE POTENTIAL FOR A WINTRY MIX...FIRST CLOSE TO
THE COAST AS THE RAIN FIRST DEVELOPS THURSDAY MORNING...THEN
PRIMARILY OVER THE NORTHERN ZONES THURSDAY INTO THURSDAY NIGHT WITH
THICKNESSES RISING OVER COASTAL CONTINUES IN RESPONSE TO A DEVELOPING
FRONTAL WAVE OVER THE NORTH CENTRAL GULF. THE ECMWF IS SLIGHTLY
WARMER AND WOULD SUGGEST SIMPLY A COLD RAIN. THE GFS HAS BEEN FAIRLY
CONSISTENT IN ITS FORECAST CRITICAL THICKNESSES AND WE WILL HAVE TO
CLOSELY MONITORED JUST HOW DRY AND COLD THE AIRMASS BECOMES PRIOR TO
THE ARRIVAL OF PRECIPITATION. IN FACT...MODELS OFTENTIMES
UNDERESTIMATES THE STRENGTH LOW LEVEL MODIFIED ARCTIC AIR. FOR
NOW...WILL MAINTAIN JUST A COLD RAIN FOR THE REGION THURSDAY INTO
FRIDAY. THE BEST CASE SCENARIO SEES HIGHS CLIMBING INTO THE 40S
DURING THE DAYTIME...BUT THAT MAY TURN OUT TO BE TOO WARM.

[Ivanhater]

12z Canadian looks like major ice and extends pretty far south. I really wish the label was not in the way

[northjaxpro]

Many times when these huge shallow surges of cold arctic air moves southward, the models often have a hard time depicting the strength and magnitude of the low level cold advection.

I have been observing the GFS model runs closely and they are very consistent on trending colder with each run. It would not surprise me in the least that even in a modified state, the arctic air mass is probably not being handled very well in regards to a consensus of how cold it may get in the coming days. I think it is very possible come Friday that freezing rain and sleet may be a big problem for areas as far south as like Lake Charles, LA, Baton Rouge, and across Mississippi to Alabama.

Very interesting situation later this week. It could get ugly again in many areas of Dixie, similar to what we saw a few weeks ago.

[BigB0882]

The GFS right now has Baton Rouge sitting at about 34/33 with a RAIN! That breaks my heart. I hope you are right, northjaxpro, that the models continue to trend colder for us. I am guessing the biggest problem is 850 temps cause it can still snow at 34 degrees if it is cold enough aloft. Any chance those temps can trend down? They give us some decent QPF, about .35 or so. The NAM shows the event starting as rain as well at about 33 degrees. The next update will show more and tell us if it sees any of it changing over to snow. We still have 4 days, so hopefully things will trend in a better direction.

Also, GFS took away our 12 day from now snowstorm. Who would have thunk it? lol

[Ivanhater]

I am becoming more concerned with ice across the deep south and Gulf coast. This looks to be a shallow arctic air mass. The Canadian is showing a major ice storm extending very far south toward the Gulf coast.

Precip is continuing to be bumped up Thursday night into Friday, now up to 60 percent while temps in the 30's. Looks messy.

[northjaxpro]

Most likely if I was a betting man, I think the models are struggling to gain a consensus to the magnitude of a shallow arctic air mass this week. I think the GFS runs have a better handle on the situation than the other reliable models, especially the Euro.

As I mentioned, with the southern branch jet flow becoming southwesterly as the shortwave moves east late this week, warm air aloft overriding that shallow low level cold layer at the surface will spell huge trouble with freezing rain in many areas by Friday.

I especially will be watching the runs later today to see if they trend toward the GFS for more of a consensus.

[MississippiWx]

Ivan, where did you find that map? Would be nice to see how far that extends down south. I'm located about 65 miles north of the Coast, so it looks like we would be close to seeing mixed precip. Wonder what the map would look like as the system progressed further to the east?

The cold air is just having a hard time making it too far east. Hopefully that will change on the next several model runs.

[MississippiWx]

Text Forecast from the NWS in Jackson, MS for Hattiesburg. They just updated this at noon. I'm sure there will be several changes between now and then (hopefully for better chances at wintry precip), but here's the initial forecast:

Thursday Night...Chance of light rain in the evening...then a chance of light rain or light sleet after midnight. Cloudy. Lows in the lower 30s. The chance of precipitation 50 percent.

Friday...Chance of light rain or light sleet in the morning... Then rain likely in the afternoon. Cloudy. Highs in the lower 40s. The chance of precipitation 60 percent.

Friday Night...Mostly cloudy with chance of light rain or light sleet in the evening...then partly cloudy with chance of light sleet and light snow after midnight. Lows in the upper 20s. The chance of precipitation 40 percent.

[northjaxpro]

Text Forecast from the NWS in Jackson, MS for Hattiesburg. They just updated this at noon. I'm sure there will be several changes between now and then (hopefully for better chances at wintry precip), but here's the initial forecast:

Thursday Night...Chance of light rain in the evening...then a chance of light rain or light sleet after midnight. Cloudy. Lows in the lower 30s. The chance of precipitation 50 percent.

Friday...Chance of light rain or light sleet in the morning... Then rain likely in the afternoon. Cloudy. Highs in the lower 40s. The chance of precipitation 60 percent.

Friday Night...Mostly cloudy with chance of light rain or light sleet in the evening...then partly cloudy with chance of light sleet and light snow after midnight. Lows in the upper 20s. The chance of precipitation 40 percent.

Trust me, look for more changes and fine tuning to that forecast as time progresses. They are watching the trends with the models closely as all of us are doing as well.

[Ivanhater]

If you are a fan of the Japanese model, this looks interesting

[Stormcenter]

I have a feeling a lot is still going to change between now and Thurs./Fri. timesframe
for folks in the Deep South. IMO

[Ivanhater]

I have a feeling a lot is still going to change between now and Thurs./Fri. timesframe
for folks in the Deep South. IMO

Hey Storm, looks like your neck of the woods will have some snow as well

[Ivanhater]

12z Euro is lock..load...repeat!

Another arctic blast next week!

[northjaxpro]

Ivanhater, looking at the long range Euro you posted above, notice the trajectory of the arctic air surge is directed more over the Eastern 2/3 of the USA, as opposed to the current surge which is diving down the lee of the Rockies straight southward into the Plains and the entire state of Texas.

Intersting to see if this holds next week. if so, brutal cold awaits the entire Eastern US.

[BigB0882]

Is that Japanese model showing snow for Baton Rouge!? Is the 540 line the "magic" line on that model. I think the trend is getting better and better for us along the coast. Just hope it continues that way. It seems so often that big events (whether it be sleet, freezing rain, snow or a mix) tend to sneak up on us with little warning. We've known about this cold blast for a while but we have been out of the winter wx discussion for a long time and now we are creeping back into it. They wont know anything until it begins to fall, most likely. Gotta love weather in the south!

[MississippiWx]

Can anyone tell me what the Euro is showing here? Is this showing a cold core system moving through Louisiana/MS during this time?

http://raleighwx.americanwx.com/models/euro/12zeuro850mbTSLPUS120.gif

http://raleighwx.americanwx.com/models/ ... PUS120.gif