Deep South Winterwx Discussion 2015-2016

[Brent]

0938 AM HEAVY SNOW CLIFTY 36.24N 93.80W
02/09/2011 E24.0 INCH MADISON AR BROADCAST MEDIA

Wow.

[Lane]

GFS text output shows .02 QPF of snow for Baton Rouge. If we could get 20:1 ratios we might get a quarter of an inch!

Looking at the radar, there isn't a ton of precip moving our way, it looks to be over relatively quickly. Is that all there will be or is another system tracking by that could bring more overnight? I don't see how we will get anything out of that, it wont crash to freezing quickly enough.

I am starting to wonder also. Looks like the system is getting here a lot faster. Is this the intitial bands of rain with more to come over night. Or is what we see on radar now all there is?

[Lane]

This from the local news station blog:

After Further Review...
There are so many factors to consider in a forecast like this. Temperature profiles, moisture, lift, all of those things can make or break the chance of snow.

After reviewing the 12z (morning) computer model guidance, I have noticed a few features that we will be watching very closely over the next 24 hours. For this discussion (and the forecast in general), I'm leaning on the NAM (North American Mesoscale) model - it has performed well with this system in Oklahoma/Kansas, and the other main model, the GFS (Global Forecast System) is trending towards the NAM with its slightly heavier precip.

There are two sneaky features that decrease confidence in the ongoing forecast - one would suggest more snow, the other would suggest less snow - and they're both found on the same chart. Here's the 700mb chart from the NAM, valid at midnight tonight with a few notations:




The first feature - the RED one with red dots around the perimeter of it - is an omega bullseye. Omega is an area of enhanced lift in the atmosphere - and when it's over the top of a sufficient area of moisture (as it is in this case), it can produce heavier precipitation AND colder temperatures than our models anticipate. If you've seen it snow above freezing, up at 34 or 35 degrees, before, the cause was likely heavy precip enhanced by strong lift.

If you take the part of that map above where it's cold enough for snow (north of US 80, roughly), and then overlay the omega field over that, the part of Alabama where those two overlap could be a "sweet spot" for a heavier stripe of snow. IF the 12z NAM is 100% correct in its placement of these features, that could very well be the general area from Montgomery to Alex City to Auburn.

Now, check out the brown area. That shows an area where dry westerly winds are punching into the backside of the moisture field. If these "dry slots" get really wrapped into the system, they can shut the precip off early, before the cold air has a chance to really get involved. This would greatly reduce the chance of accumulating snow for central Alabama.

What does all of this mean? Well, we'll probably leave much of our ongoing forecast intact...if we were to make changes, it might be to bump up the totals along I-85 and points north...If the radar and satellite trends start to show some of these features forming, we will adjust the forecast accordingly to try to account for their presence and the impact they could have on the amount of snow seen in your neighborhood.

[Ivanhater]

I don't see much of a Gulf low. The low that was forecast to move across the Gulf was in a perfect spot tracking a couple hundred miles off shore then across Tampa. However, it looks like for the Gulf coast region, we will be hit by the tail end of the front, which is never good. We need to be on the northern side of the low in the comma head, but I don't see much of a Gulf low.

[Stormcenter]

I'm looking for that GOM low off the lower TX coastline.


http://www.ssd.noaa.gov/goes/east/gmex/flash-vis.html

[northjaxpro]

I don't see much of a Gulf low. The low that was forecast to move across the Gulf was in a perfect spot tracking a couple hundred miles off shore then across Tampa. However, it looks like for the Gulf coast region, we will be hit by the tail end of the front, which is never good. We need to be on the northern side of the low in the comma head, but I don't see much of a Gulf low.

Ivan, the 18Z HPC has initialized a weak 1014mb frontal surface Low along the arctic frontal boundary centered inland in West Central Louisiana. The arctic front just passed Lake Charles during the past 90 minutes.

http://www.hpc.ncep.noaa.gov/sfc/90fwbg.gif

[Brent]

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE MOBILE AL
237 PM CST WED FEB 9 2011

...ACCUMULATING SNOWFALL POSSIBLE ACROSS PORTIONS OF INTERIOR
SOUTHEAST MISSISSIPPI AND SOUTHWEST ALABAMA TONIGHT...

.A LOW PRESSURE SYSTEM WILL MOVE EASTWARD ACROSS THE NORTHERN GULF
TONIGHT AND BRING A CHANCE OF SNOW TO PORTIONS OF INTERIOR SOUTHEAST
MISSISSIPPI AND SOUTHWEST ALABAMA. SNOWFALL ACCUMULATIONS OF AROUND
1 INCH WILL BE POSSIBLE GENERALLY NORTH OF A LINE FROM WAYNESBORO
MISSISSIPPI TO CAMDEN ALABAMA. LIGHTER AMOUNTS WILL BE POSSIBLE
NORTH OF A LINE FROM GENERALLY SOUTHERN WAYNE COUNTY TO LUVERNE
ALABAMA. A MIX OF LIGHT SNOW AND SLEET IS POSSIBLE AS FAR SOUTH AS
FROM WIGGINS MISSISSIPPI TO ANDALUSIA ALABAMA...BUT RELATIVELY WARM
GROUND TEMPERATURES ARE EXPECTED TO PREVENT ANY SNOW OR SLEET THAT
FALLS FROM ACCUMULATING.

ALZ055>058-100445-
/O.EXA.KMOB.WW.Y.0003.110210T0000Z-110210T1200Z/
MONROE-CONECUH-BUTLER-CRENSHAW-
INCLUDING THE CITIES OF...HOMEWOOD...MONROEVILLE...GREENVILLE...
LUVERNE
237 PM CST WED FEB 9 2011

...WINTER WEATHER ADVISORY IN EFFECT FROM 6 PM THIS EVENING TO
6 AM CST THURSDAY...

THE NATIONAL WEATHER SERVICE IN MOBILE HAS ISSUED A WINTER WEATHER
ADVISORY FOR SNOW...WHICH IS IN EFFECT FROM 6 PM THIS EVENING TO 6
AM CST THURSDAY.

SNOWFALL ACCUMULATIONS OF AROUND 1 INCH WILL BE POSSIBLE GENERALLY
NORTH OF A LINE FROM WAYNESBORO MISSISSIPPI TO CAMDEN ALABAMA.
LIGHTER AMOUNTS WILL BE POSSIBLE NORTH OF A LINE FROM GENERALLY
SOUTHERN WAYNE COUNTY TO LUVERNE ALABAMA. A MIX OF LIGHT SNOW AND
SLEET IS POSSIBLE AS FAR SOUTH AS FROM WIGGINS MISSISSIPPI TO
ANDALUSIA ALABAMA...BUT RELATIVELY WARM GROUND TEMPERATURES ARE
EXPECTED TO PREVENT ANY SNOW OR SLEET THAT FALLS FROM ACCUMULATING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER WEATHER ADVISORY FOR SNOW MEANS THAT PERIODS OF SNOW
WILL CAUSE PRIMARILY TRAVEL DIFFICULTIES. BE PREPARED FOR SNOW
COVERED ROADS AND LIMITED VISIBILITIES. SLOW DOWN AND USE CAUTION
WHILE DRIVING.

&&

Oxford, MS:

http://www.olemiss.edu/livecam/quadrangle/

[northjaxpro]

NWS office in Tallahassee issued a Special Weather statement for chance of wintry precip across SE Alabama and SW Georgia region for tomorrow.



SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TALLAHASSEE FL
230 PM EST WED FEB 9 2011


CHANCE OF WINTRY PRECIPITATION EARLY THURSDAY MORNING ACROSS
MUCH OF SOUTHEAST ALABAMA AND PORTIONS OF SOUTHWEST GEORGIA...

AN AREA OF LOW PRESSURE WILL TRACK ACROSS THE NORTHERN GULF OF
MEXICO TONIGHT. AS THIS STORM SYSTEM NEARS OUR REGION...A LARGE
AREA OF RAIN WILL MOVE IN FROM THE SOUTHWEST BEFORE MIDNIGHT. AS
THE LOW PRESSURE AREA TRACKS TO THE SOUTHEAST OF THE REGION EARLY
ON THURSDAY MORNING...COLDER AIR FROM THE NORTHWEST WILL MOVE IN
ACROSS SOUTHEAST ALABAMA AND INTO SOUTHWEST GEORGIA. AS THIS
OCCURS...LIGHT SNOW COULD POSSIBLY MIX WITH THE RAIN BEFORE
SUNRISE ON THURSDAY. AS MORE COLD AIR FILTERS IN...A COMPLETE
CHANGE OVER TO LIGHT SNOW OR SNOW FLURRIES WILL BE
POSSIBLE...ESPECIALLY NORTH OF A LINE FROM ELBA ALABAMA TO
LEESBURG GEORGIA...BEFORE THE CHANCE FOR PRECIPITATION ENDS AROUND
10 AM EST /9 AM CST/. SINCE SURFACE TEMPERATURES THROUGHOUT THIS
EVENT WILL REMAIN ABOVE FREEZING...NO ACCUMULATIONS OF SNOW OR ICE
IS EXPECTED.

LISTEN TO NOAA WEATHER RADIO OR YOUR LOCAL MEDIA OUTLET FOR THE
LATEST UPDATES ON THIS DEVELOPING WEATHER SITUATION

[Lane]

I dont see how that map is possible since the low is much farther south than that.

[northjaxpro]

It appears that Low pressure will form along the frontal boundary in the Central GOM and track across the Central Florida region on Thursday.

Excerpt from AFD NWS Jacksonville from late this afternoon

TONIGHT AND THURSDAY...THE NEXT GULF LOW CURRENTLY GETTING ITS ACT
TOGETHER OVER THE WESTERN GULF NEAR TEXAS. AS AN UPPER SHORTWAVE DIGS
SOUTHWARD THEN EASTWARD THE LOW WILL MOVE EAST AS A FRONTAL WAVE
THROUGH THE CENTRAL GULF CROSS FLORIDA SOMEWHERE NEAR AND ALONG
INTERSTATE 4. THIS WILL PUT MOST OF THE JACKSONVILLE AOR/FORECAST
AREA IN THE NORTHERN QUADRANTS WITH STRONG ISENTROPIC LIFT (THAT
WOULD BE "OVERRUNNING TO MY FELLOW DINOSAURS) AHEAD OF THE LOW.

[Brent]

I like how far south the black area is:



MESOSCALE DISCUSSION 0102
NWS STORM PREDICTION CENTER NORMAN OK
0303 PM CST WED FEB 09 2011

AREAS AFFECTED...NERN LA...ERN AR...CNTRL/NRN MS...SWRN TN...NWRN AL

CONCERNING...HEAVY SNOW

VALID 092103Z - 100130Z

SNOW WILL CONTINUE SHIFTING EWD ACROSS THE ARKLAMISS REGION AND
MID-SOUTH THROUGH LATE AFTERNOON INTO EARLY EVENING...WITH RATES OF
1 INCH PER HOUR EXPECTED.

MOIST ISENTROPIC ASCENT ATOP AN ARCTIC AIR MASS ADVANCING INTO THE
LOWER MISSISSIPPI VALLEY WILL CONTINUE TO SUPPORT THE EWD SHIFT OF
PRECIPITATION INTO THIS EVENING. PRECIPITATION WILL CHANGE FROM RAIN
TO SNOW ACROSS SERN PORTIONS OF THE DISCUSSION AREA AS WET-BULB
SURFACE TEMPERATURE READINGS FALL AOB FREEZING...WITH THE RAIN-SNOW
LINE LIKELY EXTENDING FROM 35 SW HSV TO 30 ENE JAN TO 35 ESE MLU BY
00Z PER THE 18Z RUN OF THE EXPERIMENTAL HRRR. SNOWFALL RATES ARE
EXPECTED TO INTENSIFY TO 1 INCH PER HOUR...AS AN AXIS OF DEEPER
MOISTURE TRAVERSES THE AREA. THE HIGHEST SNOWFALL RATES WILL BE MOST
LIKELY ALONG AND SOUTH OF THE HIGHWAY 82 CORRIDOR...WHERE THE NAM
MODEL INDICATES 800-700-MB FRONTOGENESIS INCREASING AFTER 00Z IN
CONJUNCTION WITH INCREASING SLANTWISE INSTABILITY AND PWAT VALUES OF
0.70 TO 0.80 INCH.

..COHEN/BROYLES.. 02/09/2011


ATTN...WFO...OHX...BMX...HUN...MEG...JAN...LZK...

LAT...LON 34748708 33028851 32179089 32689161 34129099 35378933
35518786 34748708

[Brent]

[Lane]

I wonder how far south of the 82 corridor. Cause I am south and east.

[BigB0882]

That radar looks great for parts of MS and AL! Enjoy it, whomever gets it! Take pics and video.

[Brent]

I wonder how far south of the 82 corridor. Cause I am south and east.

Yeah that's a big question to me, the heaviest snow is usually immediately north of the rain/snow line, so I'm feeling really good here. Below US 80 and I-85 I think is mostly rain

[Brent]

That radar looks great for parts of MS and AL! Enjoy it, whomever gets it! Take pics and video.

Camera's ready and can take 400 pictures.

[zippity]

Snow is getting started a bit early here...flurries right now; local meteorologist is hinting we might see a bit more than 1 to 2 inches...

[Brent]

Updated forecast:

Tonight...Rain in the evening. Snow until early morning...then chance of flurries late tonight. Snow accumulation around 2 inches. Lows around 30. North winds around 5 mph. Chance of precipitation near 100 percent.

Clay County just to my west:

Tonight...Snow until early morning...then chance of flurries late tonight. Snow accumulation of 2 to 3 inches. Lows around 30. North winds 5 to 10 mph. Chance of snow near 100 percent.

[Byrd]

Brent, will we in Demopolis actually get some measurable snow?!

We're always right on the line, so that usually leaves us out.

Thanks for all your information.

Byrd

[Brent]

Brent, will we in Demopolis actually get some measurable snow?!

We're always right on the line, so that usually leaves us out.

Thanks for all your information.

Byrd

It's looking pretty good. Mobile's even saying an inch or two is possible south of you(down in Clarke County).

The best moisture is probably gonna be from Demopolis to Montgomery to Auburn but it may be rain for a lot of it(though it will changeover at some point)... Just north of that line looks really good, wouldn't be surprised to see some higher end totals.