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1/25/11-1/26/11 Deep South Upper Level Low event
01-23-2011, 04:13 PM
Post: #21
1/25/11-1/26/11 Deep South Upper Level Low event
Jackson MS

Quote:THINGS GET A LITTLE MORE DICEY TUESDAY NIGHT AS THE UPPER LOW BEGINS
TO PASS OVER AND ALL OF THE MODELS SET UP A DEFORMATION ZONE OVER THE
AREA. AFTER LOOKING AT BUFR SOUNDINGS THE MODELS CONTINUE TO INDICATE
THAT THERE WILL BE SNOW PRODUCTION ALOFT...BUT TEMPS IN THE LOW
LEVELS CONTINUE TO LOOK TO WARM FOR SNOW AT THE SURFACE. ANY TIME YOU
ARE DEALING WITH A COLD CORE LOW THOUGH...THERE WILL BE SOME
POTENTIAL FOR WET-BULBING AND SNOW MAKING IT TO THE SURFACE SO WILL
CONTINUE THE POSSIBILITY IN THE GRIDS TUESDAY NIGHT AND ALSO A
MENTION IN THE HWO.

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01-23-2011, 04:15 PM
Post: #22
1/25/11-1/26/11 Deep South Upper Level Low event
Nashville,TN

Quote:SO FAR THIS SEASON WE HAVE HAD FAIRLY HIGH CONFIDENCE ON OUR SNOW
EVENT FORECASTS...BUT PATTERNS HAVE CHANGED...AND WE HAVE VERY LOW
CONFIDENCE FOR THE POSSIBLE SNOW TUESDAY NIGHT. MIDDLE TENNESSEE
WILL BE ON THE FRINGE OF A DEVELOPING EAST COAST STORM WITH MARGINAL
TEMPERATURES PROFILES. IT APPEARS OUR SOUTHEAST AND PLATEAU COUNTIES
HAVE THE BEST SHOT AT ACCUMULATING SNOW TUESDAY NIGHT BASED ON CONSENSUS
OF LATEST MODEL DATA.

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01-23-2011, 04:20 PM
Post: #23
1/25/11-1/26/11 Deep South Upper Level Low event
BMX

Quote:AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
312 PM CST SUN JAN 23 2011

.DISCUSSION...

THE GULF LOW SYSTEM MON THRU WED CONTINUES TO BE THE ONLY SYSTEM OF
INTEREST OVER THE NEXT 7 DAYS SO LET`S GET RIGHT TO IT.

THE OVERALL SYNOPTIC SET UP REMAINS THE SAME AS EACH FORECAST MODEL
CONTINUES TO SHOW A DIGGING UPPER TROF AND A DEVELOPING GULF LOW.
THE 12Z GFS AND ECMWF SOLUTIONS APPEAR PRETTY CONSISTENT WITH EACH
OTHER IN THE TIMING AND TRACK OF THE SFC LOW...BUT THERE ARE SOME
DIFFERENCES. WILL CONTINUE TO GO WITH MORE OF A GFS/ECMWF BLEND FOR
THE PERIOD MON THRU WED.

THE SFC LOW DEVELOPS IN THE NW GULF ON MON AND THEN SLIDES ENE INTO S
GA BY WED MRNG. PRECIPITATION COULD BEGIN AS EARLY AS MON EVENING
IN THE WEST AND THE OVERSPREAD THE ENTIRE CWA ON TUE. LOW LEVEL
TEMPS WILL BE TOO WARM FOR ANY FROZEN PRECIP THRU TUE AFTN. THE
REALLY TRICKY PART COMES TUE EVNG INTO WED MRNG. AT FIRST GLANCE
THIS LOOKS LIKE A CLASSIC SNOW SET UP FOR NORTH AND CENTRAL
ALABAMA...AS FAR AS THE LOCATION AND INTENSITY OF THE SFC LOW...BUT
THINGS JUST AREN`T ADDING UP TO MUCH SNOW JUST YET. HOWEVER THIS
COULD CHANGE SIGNIFICANTLY WITH EVEN THE SLIGHTEST BIT OF CHANGE IN
SFC TEMPS AND/OR THE TRACK OF THE SFC LOW.

AFTER LOOKING AT THE 12Z GFS...WE HAVE VERY LITTLE ROOM FOR ERROR
WHEN IT COMES TO GETTING ALL RAIN OR SEVERAL INCHES OF SNOW. THE GFS
IS SPITTING OUT LARGE AMOUNTS OF QPF AND FAIRLY HIGH PRECIP RATES
TUE NIGHT INTO WED MRNG. THESE HIGH RATES ARE MOST LIKELY DUE TO THE
DEVELOPMENT OF A TROWAL AND PRETTY DECENT FRONTOGENETICAL FORCING.
THE QUESTION WILL BE WHETHER OR NOT THESE PRECIP RATES WILL BE HIGH
ENOUGH FOR DYNAMIC COOLING TO BRING COOLER TEMPS DOWN TO THE SFC.
GFS PROFILE TEMPS AT THE SFC (AND UP TO AROUND 850 MB) ARE A FEW
DEGREES ABOVE FREEZING...WITH PLENTY OF MOISTURE UP TO 300 MB.
THEREFORE ALL IT WILL TAKE IS COOLING THE SFC TEMPS DOWN BY A DEGREE
OR TWO FOR US TO SEE RAIN SWITCH OVER TO ALL SNOW ACROSS THE NRN
PORTION OF THE CWA. IF YOU TAKE THE GFS SOUNDING AT 12Z WED FOR
ANYWHERE IN NORTH CENTRAL AL AND COOL THE LOWEST LEVELS BY LET`S SAY
2 DEGREES THEN YOU COULD HAVE SOME PRETTY SIGNIFICANT SNOWFALL. THE
ECMWF IS A LITTLE COOLER THAN THE GFS BUT EVEN IT IS STILL
QUESTIONABLE. FOR NOW...FEEL MOST COMFORTABLE LEAVING RAIN OR SNOW
WORDING IN FOR THE NRN HALF OF THE CWA TUE NIGHT/WED MRNG...WITH ALL
RAIN TO THE SOUTH AS TEMPS ARE JUST TOO WARM THERE. WILL WAIT AND
SEE IF MODELS TREND SFC TEMPS COOLER...IF THAT HAPPENS THEN WILL
HAVE TO MAKE SOME MAJOR ADJUSTMENTS TO THE WX GRIDS AND INTRODUCE
SOME SNOW AMOUNTS. MOISTURE EXITS THE AREA BY WED AFTN AS THE SFC
LOW SLIDES OFF THE ATLANTIC COAST...THUS ENDING PRECIP CHANCES.

DID NOT MAKE MANY CHANGES TO THE FORECAST PAST WED...WANTED TO ALLOW
SUFFICIENT TIME TO FOCUS ON THE UPCOMING SYSTEM. MODELS CONTINUE TO
BRING SEVERAL UPPER LEVEL IMPULSES ACROSS THE AREA FROM WED INTO
THE WEEKEND WHICH WILL BRING PERIODIC CLOUDINESS TO PORTIONS OF
CENTRAL AL. TEMPS WILL REMAIN JUST BELOW NORMAL THRU SAT.

19

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01-23-2011, 04:23 PM
Post: #24
1/25/11-1/26/11 Deep South Upper Level Low event
[Image: image_full5.gif]

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01-23-2011, 05:31 PM
Post: #25
1/25/11-1/26/11 Deep South Upper Level Low event
Bill M

Quote: [Image: avw.php?zoneid=1&cb=INSERT_RANDOM_NU...n=a4a1784d]
Afternoon Forecast Update

Bill Murray | 2:49 pm January 23, 2011 | Comments (15)
[Image: 2011-01-23_14-50-31.png]
High clouds streaming across the northern half of the state have blocked much of the sunshine and caused temperatures to struggle to get out of the 40s this afternoon. Once you get south of Calera, skies become sunny and temperatures have warmed to above 50F. Over Northeast Alabama, temperatures have struggled to get out of the 30s thanks to the clouds and an easterly wedge nosing into the state from Georgia.
Those radar echoes over Northwest Alabama are very light and not reaching the ground for the most part, although I wouldn’t rule out a few sprinkles in that area.
TONIGHT: Tonight should feature fair skies south, with continued mostly cloudy conditions north. Temperatures should bottom out in the lower and middle 30s, with areas under clear skies actually getting colder. It now looks like we might get through the day on Monday with little in the way of showers. There could also be a little more sunshine, which might let the mercury make the 50s. Those showers will finally arrive Monday night, with lows dropping to near 40F.
TUESDAY THREAT: We have been fairly confident that a low pressure system would develop over the western Gulf of Mexico and track eastward this week. That looks on track. With cold air in place over the South, that can be a recipe for wintry precipitation. The devil is in the details, as they say.
THE DETAILS: The track and intensity of the low are critical. On Saturday, it appeared that the low would be in the perfect sweet spot to bring snow to North and Central, and perhaps even South Alabama. Far enough to the south not to bring too much warm air north, yet strong enough to throw moisture into the cold air and draw more cold air in on the backside of the system as it roared up the coast. Think 1993 Superstorm, on a smaller scale.
Well, one model saying that by itself is one thing, but our two major models and their European counterpart chiming in with the same solution, that sets off alarm bells in the old weather office. Since Saturday morning the models have not been as bullish on the idea of the big low being in the right spot for a significant accumulating snow.
But for now, confidence is increasing in a forecast that includes rain to be rain spreading into the area early during the day on Tuesday, possibly mixing with snow over the northern half of the area late Tuesday night and continuing into Wednesday morning. There still could be some surprises with this system, including the possibility of some accumulations late Tuesday night into Wednesday in places where something we call dynamic cooling occurs with the strong upper system aloft moving overhead.
Here is the look for after midnight early Wednesday from the GFS and the NGM.
[Image: 2011-01-23_14-44-38.png]
[Image: 2011-01-23_14-45-35.png]
The dotted blue line reflect the models’ ideas of roughly where it could be cold enough for the rain to mix with snow. Dynamic upper systems like this one though can fool the models and make a colder atmospheric temperature profile that can support snow. Hence the idea that surprises are not off the table with this one.
Wednesday will be cool and blustery with a freshening northwesterly wind as the low pressure system intensifies and gets ready to head up the East Coast as a blockbuster storm. Skies should clear during the day and highs will only be in the 40s.

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01-23-2011, 11:43 PM
Post: #26
1/25/11-1/26/11 Deep South Upper Level Low event
[Image: nam_500_066s.gif] MSLP 1000 - 500mb hour: 066

[Image: nam_slp_066s.gif] 700mb RH, Ht hour: 066

[Image: nam_700_066s.gif] 850mb Temp, Ht hour: 066

[Image: nam_850_066s.gif]

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01-24-2011, 05:10 AM
Post: #27
1/25/11-1/26/11 Deep South Upper Level Low event
[Image: image2.gif]

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01-24-2011, 05:10 AM
Post: #28
1/25/11-1/26/11 Deep South Upper Level Low event
Looks like a cold rain event for Alabama Smile NEXT

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01-24-2011, 08:45 AM
Post: #29
1/25/11-1/26/11 Deep South Upper Level Low event
[video=youtube;sv6i2-cma_c]http://www.youtube.com/watch?v=sv6i2-cma_c&feature=player_embedded#![/video]

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01-24-2011, 09:00 AM
Post: #30
1/25/11-1/26/11 Deep South Upper Level Low event
At this time the snow chase is on for Tuesday night/ Wed Morning and we will be streaming live Smile

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