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January 2011 Part 2


MotoWeatherman

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GSP:

LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...

AS OF 310 PM WED...

IT IS WAY TOO EARLY TO GIVE A DEFINITE SNOW AMOUNT FORECAST.

HOWEVER...IF THE CURRENT MDLS ARE CORRECT...THEN A WINTER STORM

WARNING LEVEL SNOW WOULD FALL ACROSS MOST OF THE AREA...XCPT MAYBE

THE FAR SOUTHERN CWFA.

You know things are looking good when you see GSP starting to get amps up this far out. :popcorn:

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At 120, 0.1" line is up to I-40 on ensembles.. OP had it at NC/SC border, so there's a lean from the ensembles toward a further north precip shield. 0 line further north on ensembles compared to operational. Cuts through N GA and upstate SC instead of C GA and lower SC.

Interesting... don't want a N trend to kill us like December 2009. Probably a very different scenario then. I should go back and read the NCSU case study, actually.

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A snippet from BMX's Hazardous Weather Outlook:

A WINDOW OF OPPORTUNITY FOR ACCUMULATING WINTER PRECIPITATION WILL

BE POSSIBLE IN PARTS OF CENTRAL ALABAMA FROM SUNDAY MORNING THROUGH

MONDAY EVENING. A STORM SYSTEM WILL MOVE ACROSS THE SOUTHEASTERN

STATES AND NORTHERN GULF OF MEXICO OVER THE WEEKEND. FORECAST

CONFIDENCE IS LOW AT THIS TIME...DUE TO UNCERTAINTIES CONCERNING

THE STRENGTH...TIMING...AND TRACK OF THIS SYSTEM.

:sled:

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They actually sound more bullish than RAH.

As they generally are, and arguably should be. Could be more intense as of now in their CWA.

Too much cold air in place for this, it would have to go really north to kill us.

Yup... just read the case study. It also tracked waaaayyyyy further west.

If this verifies, it could get pretty cold with the snow cover.

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XUS62 KFFC 052034

AFDFFC

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE PEACHTREE CITY GA

334 PM EST WED JAN 5 2011

.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...

LATEST ANALYSIS SHOWS LOW PRESSURE TAKING SHAPE ACROSS EASTERN

MISSISSIPPI THROUGH ALABAMA AND WEST GEORGIA WITH PERSISTENT WEDGE

EAST OF THE APPALACHIANS FINALLY BEGINNING TO SHIFT EAST OF THE

AREA. FIRST WAVE OF PRECIP IS SHIFTING QUICKLY EAST OF THE AREA

WITH MOST SIGNIFICANT RAIN RIDING SOUTHEAST ALONG AN OLD FRONTAL

BOUNDARY. THIS WILL REQUIRE A REDUCTION TO POPS FOR THE

INITIALIZED GRIDS FOR THE SOUTHERN 2/3RDS OF THE FORECAST AREA AS

UPSTREAM RADARS INDICATE LITTLE RESIDUAL ACTIVITY FOR THE

REMAINDER OF THE OVERNIGHT. SECOND BATCH OF PRECIP IS MOVING

SOUTHEAST FROM THE TENNESSEE VALLEY...THE RESULT OF A STRONG

SHORTWAVE EMBEDDED IN AN EAST COAST TROUGH. SURFACE ANALYSIS ALSO

INDICATES A SUBTLE TROUGH AXIS ALONG NORTH GEORGIA AND ALABAMA

WHICH SHOULD ALLOW FOR BRIEF ENHANCEMENT OF PRECIP AS SHORTWAVE

MOVES THROUGH.

GREATEST FORECAST CHALLENGES WILL INVOLVE THE POTENTIAL FOR WINTRY

PRECIP IN THREE DIFFERENT EPISODES...THE FIRST OF WHICH IS TONIGHT

FOR THE MOUNTAINS. AFOREMENTIONED PRECIP WILL CONTINUE TO MOVE IN

AND AS LOW PRESSURE MOVES EAST OF THE AREA...COLDER AIR WILL BEGIN

TO DRAIN IN ON THE BACK SIDE. WILL BE MORE OF A TIMING ISSUE THAN

ANYTHING ELSE AS WET BULBS LOWER BUT SUFFICIENT MOISTURE DEPARTS

IN TANDEM. BASED ON RADAR PRESENTATION AND CURRENT TEMPS WHICH ARE

SLIGHTLY BELOW GUIDANCE...IT LOOKS AS THOUGH THERE WILL BE A SMALL

WINDOW FOR -RA TO MIX WITH AND POSSIBLY BRIEFLY CHANGE OVER THE -SN

IN THE MOUNTAINS. WILL NOT CARRY ANY ACCUMULATIONS AT THIS POINT...

BUT CONDITIONS WILL NEED TO BE MONITORED BY EVENING SHIFT.

NEXT SYSTEM WILL BE A NORTHWEST FLOW EVENT AS STRONG IMPULSES

CONTINUE TO ROUND THE BASE OF THE TROUGH. TEMPERATURE PROFILES

FORM AREA SOUNDINGS INDICATE THIS ONE WILL BE AN ALL SN EVENT WITH

CRITICAL THICKNESSES ALL POINTING TO THIS. MEAN RH VALUES WILL

INCREASE TO BETWEEN 70 AND 90 PERCENT WITH THIS SYSTEM AS IT MOVES

THROUGH WITH A 00Z FRIDAY ONSET TIME AND A PEAK AROUND 12Z FRIDAY.

ALTHOUGH PRECIP WILL BE LIGHT FOR THIS EVENT...IT WILL BE OF RELATIVELY

LONG DURATION WITH ACCUMULATING SNOW POSSIBLE THROUGHOUT. AT THIS

POINT...IT APPEARS SN AMOUNTS WILL BE BELOW ADVISORY CRITERIA...

GENERALLY AN INCH OR LESS... BUT THIS COULD CERTAINLY CHANGE IN

LATER SHIFTS SHOULD MODEL TRENDS CONTINUE.

ONCE PRECIP CLEARS OUT FRIDAY NIGHT...ATTENTION WILL TURN TOWARD

THE WEST WHERE SOUTHERN STREAM LOW WILL BE MOVING ASHORE IN THE

VICINITY OF SOUTHERN CALIFORNIA. THIS SYSTEM WILL PLAY AN

IMPORTANT ROLE IN AN INTERESTING AND CHALLENGING EXTENDED PERIOD.

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...

DESPITE EXCELLENT MODEL AGREEMENT FOR THE EXTENDED PERIOD...

CONFIDENCE REMAINS LOW DUE TO MAIN PLAYER BEING A CUTOFF LOW WHICH

HAS YET TO MAKE AN APPEARANCE ON THE US MAINLAND. CONFIDENCE IS

FURTHER DIMINISHED BASED ON GFS POOR PERFORMANCE WITH LAST WEST

COAST UPPER SYSTEM WHICH AFFECTED THE AREA TWO WEEKS AGO. THAT

SAID...WITH THE ECMWF BEING MORE CONSISTENT THIS WINTER AND HAVING

SUPPORT FROM OTHER GLOBAL MODELS...WILL FOLLOW THE PATTERN OF A

DEVELOPING LOW OVER THE NORTHERN GULF OF MEXICO IN RESPONSE TO

DAMPENING SHORTWAVE OVER THE LOWER MISSISSIPPI VALLEY LATE IN THE

WEEKEND INTO MONDAY. MEANWHILE...A STRONG HIGH WILL BE NOSING DOWN

FROM THE OHIO VALLEY WITH VALUES NEAR 1030 MB FOR NORTHERN

SECTIONS. BASED ON CONSENSUS...HAVE INCREASED POPS TO HIGH END

CHANCE FOR THE SOUTHERN SECTIONS WHICH COULD REALLY BE LIKELY IF

CONFIDENCE WERE HIGHER. MORE UNCERTAIN TO THE NORTH WHERE HIGH

COULD BE STRONGER THAN ADVERTISED AND IT WOULD BE MORE OF AN

INCREASE IN CLOUDS THAN PRECIP. THE ONE CERTAINTY WILL BE THAT

PRECIP TYPE WILL BE A DEFINITE CONCERN. MODEL SOUNDINGS SHOW

POTENTIAL FOR ALL SNOW FOR NORTHERN 2/3RDS OF AREA AND A MIX TO

THE SOUTH. GIVEN CONFIDENCE LEVELS AND THE FACT WE HAVE A WHILE

UNTIL THIS EVENT UNFOLDS...WILL WORD FOR RA/SN OVER THE NORTHERN

HALF AND RA TO THE SOUTH...BUT EXPECT ADJUSTMENTS TO THIS BY

SUBSEQUENT SHIFTS.

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This storm has the look of a throwback to a bygone era. Others have already referenced it, but this storm has a lot of similarities to the one folks in Atlanta call SnowJam in Jan '82. If you look at the NARR maps from Jan 10-15, 1982 (Jan 10, 1982) , it starts on Jan. 10 with a polar vortex over the Great Lakes, a super cold air mass in the central and eastern U.S., and a cutoff low off Baja California. The upper wave ejects out of the SW states and is followed by a second wave diving down through the northern Rockies...all very similar to the current setup. Compared to today's model runs, the upper wave ejecting out of the SW was weaker in '82, but the trailing wave was stronger and more amplified.

The least of my concerns with this pending storm is suppression. The trailing upper wave diving down through the Rockies will force the initial wave to move, at a minimum, east, but more likely, northeast, throwing moisture into the SE states. Bigger concerns to me would be the initial wave weakening too much and the trailing wave not falling in to place to provide the 2nd surge of moisture. And lastly, temps are always a concern with snow in the SE, but as of now, a lot of areas are looking good in that dept. I like seeing the single digit dewpoints for Sunday on the GFS output (see that in ATL and CLT). All in all, it doesn't get much better than this in the SE with 4-6 days to go.

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Middle Tennessee has been NW of the game this year. What is it going to take! Lots of time for the precip shield to move North.

My opinion on Nashville and north.

Precip will be further north than indicated by the Euro. I wouldn't be surprised to see I-40 in accumulating snow from the weekend storm. What is more interesting to me for BNA is the second impluse that is racing to catch the wave around the southeast coast. This very well could streak snow in west to east fashion across much of Tennessee, yielding a secondary 2-4 inch type snowfall.

This sure looks like the two wave attack I envisioned a few days ago and posted on the site. Time will tell, but while you are not in the "optimal" spot at this point, you are certainly in the ballgame for some fun and games before this all sweeps through Tuesday and Wednesday of next week.

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This storm has the look of a throwback to a bygone era. Others have already referenced it, but this storm has a lot of similarities to the one folks in Atlanta call SnowJam in Jan '82. If you look at the NARR maps from Jan 10-15, 1982 (Jan 10, 1982) , it starts on Jan. 10 with a polar vortex over the Great Lakes, a super cold air mass in the central and eastern U.S., and a cutoff low off Baja California. The upper wave ejects out of the SW states and is followed by a second wave diving down through the northern Rockies...all very similar to the current setup. Compared to today's model runs, the upper wave ejecting out of the SW was weaker in '82, but the trailing wave was stronger and more amplified.

The least of my concerns with this pending storm is suppression. The trailing upper wave diving down through the Rockies will force the initial wave to move, at a minimum, east, but more likely, northeast, throwing moisture into the SE states. Bigger concerns to me would be the initial wave weakening too much and the trailing wave not falling in to place to provide the 2nd surge of moisture. And lastly, temps are always a concern with snow in the SE, but as of now, a lot of areas are looking good in that dept. I like seeing the single digit dewpoints for Sunday on the GFS output (see that in ATL and CLT). All in all, it doesn't get much better than this in the SE with 4-6 days to go.

Yep really is a great site to see.

BTW the 18z NAM is close to the Euro, the low might be a hair south but the moisture spread is wider on the NW end.

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Ahhh...the good ol days :wub:

While I don't mind a good ice storm...it would be nice to have one of Tony's sleet storms :guitar: Alot of options are on the table, with alot of model runs to go...this will be fun to watch unfold :thumbsup:

Ah, you'd love it. I've seen a few big snows here, nearing a foot several times (unofficial Larry) and I wouldn't trade the beauty of the 92 Jan snow fall and some I saw in Germany...the Black Forest in heavy snow will always ramain high on my list...but a good thumping of sleet can't be beat. Something solid and determined about 5 or 6 inches sleet and a bit of mix. And the roar of it...impressive. Hope you and Jose get to enjoy a huge hit up there, but I'm still on the fence yet. Could be a lot of zrain if I get too much waa so I want a track down in Fla. not crossing south Ga. If it is a lot of precip like I think it will be, I'd take cold rain everyday over 2 inches of zrain. Everyday! T

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:arrowhead: I am going to plead the fifth on that....3-6 is a great standard response at this stage and I would feel fairly confident in that but as Alan mentioned earlier the Dec 2000 debacle that followed the Jan 2000 greatest storm ever...learned a good lesson from Kocin that year...he was very skeptical of the Dec storm while all of us were weenie-ing about a repeat of 20" of snow again. Climo climo climo; his voice echoes through my head....so I look at this and know that it is extremely rare to get back to back decent snows here (I am sure Larry can help us here) but also note that such a blocking pattern does exist where this is possible.,.so much can go wrong though. I had nearly 6 inches and there was virutally nothing in Knoxville...just 50 - 60 miles as the crow flies from my house. So at 96+ hours and now 40+ years of age...I just kind of prefer to watch and wait...knowing this is a solid chance...I also failed at the Mega Millions last night which I was sure I was going to win....:gun_bandana:

Gotten cynical in your old age huh? :P Good points though, and as much as I hate relying on climo to predict current events, one has to consider your point.

I know one thing though, everyone wishes you would post more.

GSP:

LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...

AS OF 310 PM WED...ALTHOUGH THERE ARE STILL SOME DIFFERENCES IN THE

MDL GUIDANCE...CONFIDENCE IS INCREASING THAT A WINTER STORM WILL

AFFECT THE AREA FROM LATE SUNDAY INTO TUE NITE...THEN CONTINUE

ACROSS THE NW FLOW AREAS THRU THE END OF THE PERIOD. A SRN STREAM

UPPER LOW WILL OPEN UP AND MOVE ACROSS THE GULF COAST STATES INTO

THE CAROLINAS THRU MONDAY. THIS LOW DAMPENS OUT BUT ANOTHER SHORT

WAVE CARVES OUT A CLOSED UPPER LOW OVER THE LOWER OH VALLEY TUESDAY

THEN THIS LOW MOVES ACROSS THE CAROLINAS ON WED. THE 12Z ECMWF AND

GFS AGREE FAIRLY WELL ON THIS UPPER PATTERN. THE SFC RESULT IS ANY

LINGERING NW FLOW SNOW ENDS SUNDAY NIGHT. THEN A SFC LOW MOVES ALONG

THE GULF COAST SUN AND SUN NITE...THEN MOVES INTO THE ATLANTIC LATE

MONDAY OR MON NITE. THE GFS IS STILL A TAD SLOWER AND FARTHER SOUTH

WITH THE PRECIP AT ONSET. THE ECMWF WAS QUITE CONSISTENT FROM ITS

00Z RUN...THE GEFS MEAN IS CLOSER TO THE ECMWF TIMING AND HPC IS

LEANING THIS WAY WITH THE FCST SO I WILL AS WELL. THE GEM IS THE

ONLY MDL STILL FORECASTING A MILLER B TYPE SYSTEM...BUT IT DOES

AGREE MORE WITH THE ECMWF REGARDING PRECIP ONSET. THE ECMWF AND THE

GFS ARE SIMILAR WITH THEIR THERMAL STRUCTURE...LENDING CONFIDENCE

THAT WE AREA LOOKING AT A RAIN/SNOW SCENARIO INSTEAD OF A MIXED

BAG/ICE SCENARIO IN THE MILLER B GEM.

THEREFORE...HAVE SLIGHT CHC POP SPREADING ACROSS THE AREA SUNDAY

WITH CHC ACROSS THE WRN CWFA SUN NITE AND ALL AREAS MONDAY AS

DEFORMATION ZONE MOVES OVER THE AREA. HAVE A RAIN/SNOW MIX OR RAIN

OUTSIDE OF THE MTNS DURING THE DAY GIVEN THE FCST HIGHS. HOWEVER...

SOUNDINGS WOULD INDICATE THAT TEMPS WOULD WET BULB BELOW FREEZING

EVEN DURING THE DAY. HAVE HIGHEST CHC OF PRECIP TUE NITE AS BOTH

MDLS SHOW THE DEFORMATION ZONE PIVOTING ACROSS THE AREA AS THE LOW

BEGINS MOVING UP THE COAST. THIS WOULD BE WHEN THE HEAVIEST SNOW

WOULD FALL. PRECIP CHC TAPERS OFF FROM SOUTH TO NORTH TUE AFTERNOON

AS THE DEFORMATION ZONE MOVES NORTH. PRECIP ENDS ALL AREAS OUTSIDE

OF THE MTNS TUE NITE AS LIFT AND MOISTURE MOVE NORTH. HOWEVER...NW

FLOW SNOW BEGINS AND CONTINUES THRU WED IN THE USUAL AREAS.

IT IS WAY TOO EARLY TO GIVE A DEFINITE SNOW AMOUNT FORECAST.

HOWEVER...IF THE CURRENT MDLS ARE CORRECT...THEN A WINTER STORM

WARNING LEVEL SNOW WOULD FALL ACROSS MOST OF THE AREA...XCPT MAYBE

THE FAR SOUTHERN CWFA.

I like how they added "except the extreme cwa". They said the same thing with the last one and looked what happened. I don't see any compelling evidence to suggest their southern cwa would not be hit. In fact, they have a higher chance of getting more due to forecasted precip amounts. Just my 2 cents though.

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