Jan. 1-4 SE Winter Storm, Possibility: Medium Range (4-7 Days Out) Forecasts Options

[ShawnEastTN]

Creating a thread on this potential storm for at least the northern edges of the Southeast.

This post has been edited by ShawnEastTN: Dec 27 2012, 04:22 PM

[ShawnEastTN]

This from NWS Morristown for this period:

AN UPPER
RIDGE BUILDS IN FOR SUNDAY AND MONDAY. MODELS DIVERGE AS THE NEXT
SYSTEM APPROACHES THE AREA MONDAY NIGHT AND TUESDAY. CONFIDENCE
BECOMING QUITE LOW AT THIS POINT AND WILL KEEP POPS AT CHANCE
CATEGORY MONDAY NIGHT AND TUESDAY...AND LOWER TO 20 POPS FOR TUESDAY
NIGHT.

GFS AND ECMWF NOT IN AGREEMENT ON PATTERN EVOLUTION FOR WEDNESDAY
THROUGH THURSDAY NIGHT. ECMWF WANTS TO START BRINGING IN PRECIP ON
WEDNESDAY FROM A CUT OFF LOW OVER TEXAS. LOW IS SLOW TO PROPAGATE
EASTWARD BUT EVENTUALLY GETS PICKED UP BY A TROUGH SWINGING DOWN
FROM THE NORTH ON FRIDAY EVENING INTO SATURDAY MORNING. GFS IS MUCH
FASTER AS IT DOES NOT WANT TO CUT OFF THE LOW. GFS WASHES OUT THE
LOW BEFORE IT EVER REACHES THE SOUTHERN U.S. BECAUSE OF THIS...GFS
IS MUCH DRIER THROUGH THIS PERIOD. FOR NOW...GOING WITH A BLEND OF
THE TWO BUT FAVORING GFS. CARRIED SLIGHT CHANCE OF POPS THROUGH THIS
PERIOD.

Appears lots of uncertainty... Euro sounds nice, though local NWS opting for a blend with GFS for forecast guidance.

[ShawnEastTN]

NWS Nashville early morning disco met leaning toward Euro:

THE NEXT WAVE SPREADS ITS
MOISTURE OVER US ON MON WITH POPS INCREASING TO THE CHANCE LEVEL
FOR MON THROUGH TUE NGT. HOWEVER...BY TUE THE GFS AND ECM START TO
DIVERGE SIGNIFICANTLY. I HAVE LEANED MORE TOWARD THE ECM FOR THIS
TIME PERIOD. AND AGAIN WITH THE NGT TO DAY TEMP RANGE THERE IS A
MIX OF RAIN AND SNOW FOR THIS TIME PERIOD.

ONE LAST THING...AFTER 44 YEARS OF FEDERAL SERVICE...YOURS TRULY
WILL RETIRE TO THE RANKS OF ROCKING CHAIR FORECASTERS. I HOPE MY
COMMENTS IN THESE MISSIVES HAS BEEN OF SOME VALUE TO YOU. GOODBYE
AND GOOD LUCK TO YOU ALL.

JIM MOSER

[ShawnEastTN]

NWS Memphis disco met leaning toward Euro:

MONDAY WILL BE A BIT WARMER BEFORE A
FAST MOVING CLIPPER FRONT SWEEPS THROUGH THE REGION BY AFTERNOON.
THIS FRONT FOR NOW APPEARS MOSTLY DRY SO ONLY INTRODUCED A SLIGHT
CHANCE FOR RAIN MONDAY AFTERNOON. LATER THAT NIGHT AS THE UPPER
LEVEL HEIGHTS START BUILDING IN RESPONSE TO THE SOUTHWEST STORM.
DEEPER MOISTURE WILL OVERRIDE THE POST FRONTAL AIRMASS WITH THE
NEXT CHANCE FOR POTENTIAL WINTER WEATHER COMING NEW YEAR`S EVE NIGHT.

EXTENDED PERIOD...THE GFS AND EURO DIFFER IN THE TIMING OF A DEEP
SHORTWAVE TROUGH CROSSING THE SOUTHERN PLAINS. HAVE LEANED MORE
WITH THE EURO WHICH INDICATES A SPLIT JET PATTERN ACROSS THE
CENTRAL U.S. CAUSED BY A BUILDING UPPER RIDGE OVER THE CANADIAN
ROCKIES. THIS SOLUTION WOULD CONTINUE A LIGHT OVERRUNNING PATTERN
IN THE MIDSOUTH ON TUESDAY AND WEDNESDAY WITH TEMPERATURES
HOVERING AROUND FREEZING ACROSS THE NORTHERN COUNTIES. IT ALSO
INTRODUCES A BETTER POTENTIAL FOR WINTER PRECIPITATION TO AFFECT
THE MIDSOUTH JUST BEYOND THIS FORECAST PERIOD AS THE STORM
CROSSES THE LOWER MISSISSIPPI VALLEY.

[winterwarlock]

Area Forecast Discussion
Issued by NWS Wakefield, VA

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
SFC HIGH PRESSURE BUILDS OVER THE REGION FROM THE SW SUNDAY NIGHT
INTO MONDAY FOR DRY WX. THE NEXT STORM SYSTEM IS THEN EXPECTED TO
IMPACT THE REGION LATE MONDAY NIGHT THROUGH EARLY WED MORNING. THE
OPERATIONAL RUNS OF THE ECMWF AND GFS HAVE COME INTO BETTER
AGREEMENT ON HOW TO HANDLE THIS SYSTEM BUT STILL SOME MINOR
DISCREPANCIES THAT WILL HAVE TO BE WORKED OUT IN THE COMING DAYS.
SOUTHERN STREAM MOISTURE IS SHOWN TO OVERSPREAD THE REGION LATE
MONDAY NIGHT INTO TUESDAY BEFORE SLIDING OFF THE COAST TUESDAY
NIGHT/EARLY WED MORNING. WHAT THE MODELS SEEMS TO DIFFER ON IS HOW
FAR SOUTH THIS MOISTURE IS SUPPRESSED DUE TO NORTHERN STREAM
ENERGY/ARCTIC AIRMASS MOVING SOUTH OUT OF CANADA. IT APPEARS AS IF
THE BATTLEGROUND BETWEEN THE NORTHWARD MOVING MOISTURE AND THE
SOUTHWARD MOVING COLD AIR WILL BE OVER THE MID-ATLANTIC REGION...SO
P-TYPE WILL BE AN ISSUE FOR OUR FA. INITIAL WARM SURGE MAY AID IN
BRINGING PRIMARILY RAIN TO THE FA INTO TUESDAY...BUT WITH A WAVE OF
LOW PRESSURE POSSIBLY DEVELOPING ALONG THE FRONT LATE TUESDAY AS
COLDER AIR BEGINS TO WORK SOUTH...COULD SEE RAIN MIX WITH OR
CHANGE OVER TO SNOW BEFORE ALL PRECIP ENDS LATE TUES NIGHT/EARLY WED
MORNING (EXCEPTION WOULD BE SERN FA WHERE PRECIP LIKELY TO STAY AS
ALL RAIN). CHILLY HIGH PRESSURE THEN RETURNS NEXT WEDNESDAY AND
THURSDAY. HIGH TEMPS THROUGH THE PERIOD GENERALLY IN THE UPR 30S TO
THE MID 40S. LOWS TEMPS IN THE 20S AND 30S.

&&

[Weather4LA]

REA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
340 PM CST FRI DEC 28 2012

. . . . . . .

OVERALL...MODELS STILL ADVERTISING A QUASI SPLIT FLOW UPPER LEVEL
PATTERN THROUGH THE EXTENDED PERIOD. THE FIRST SOUTHERN BRANCH
DISTURBANCE PHASING IN WITH NORTHEAST CONUS SECTOR TROUGHING WILL BE
DAMPENING AND HEADING IN THIS DIRECTION BY MONDAY. BEFORE THAT TIME
EXPECT MAJOR RIGHT ENTRANCE REGION JET DYNAMICS TO BE GRADUALLY
INCREASING CLOUD OVER FOR THE ARKLAMISS SUNDAY THROUGH SUNDAY NIGHT
WHILE TEMPERATURES REMAIN A LITTLE BELOW NORMAL. ACTUAL RAIN LOOKS
TO COME IN FROM WEST TO EAST ON MONDAY AND COULD EVEN MIX WITH SOME
THUNDERSTORMS (AT LEAST IN SOUTHERN ZONES) LATE MONDAY THROUGH EARLY
TUESDAY. GFS SUGGESTS MAJOR NORTHWARD GULF MOISTURE TRANSPORT IN
THIS LATTER TIME PERIOD WITH ASSOCIATED SURFACE LOW PRESSURE
TRACKING NORTH OF THE COAST. CONSENSUS OF MODELS IS SOMEWHAT MORE
SUPPRESSED WITH MOISTURE TRANSPORT NOT QUITE AS GREAT. AT THIS POINT
IT SEEMS THE PROBABILITY OF ANY SEVERE CONVECTION IS PRETTY
LOW...BUT THE RAINFALL ASPECT WILL HAVE TO BE WATCHED SINCE RATES
COULD GET PRETTY HIGH (ESPECIALLY IF THE GFS SOLUTION IS MOST
CORRECT). FOR NOW I HAVE DECIDED TO HOLD OFF ON INTRODUCING ANYTHING
IN THE HWO SINCE MORE SUPPRESSED SOLUTIONS KEEP THE MORE TROUBLESOME
RAIN RATES FROM MATERIALIZING.

THE PASSAGE OF THE FIRST DAMPENING DISTURBANCE WILL LIKELY DRIVE A
COLD FRONT DOWN TO...OR SOUTH OF...THE COAST BY LATE TUESDAY. BUT
THERE WILL STILL BE ANOTHER PIECE OF UPPER LEVEL ENERGY TO COME AT
THE REGION FROM OUT OF THE DESERT SOUTHWEST BY LATE TUESDAY NIGHT OR
WEDNESDAY. THIS FEATURE WILL LIKELY TRIGGER LOW PRESSURE DEVELOPMENT
DOWN IN THE GULF ALONG THE DEEPER BAROCLINIC ZONE. RAIN ASSOCIATED
WITH THE EXPECTED LOW TO OUR SOUTH SHOULD TRACK AT LEAST ACROSS
SOUTHERN AREAS WEDNESDAY INTO THURSDAY. HEAVY RAIN AND/OR STORMS DO
NOT LOOK LIKE A PARTICULARLY GOOD BET WITH THIS SECOND SYSTEM...BUT
THERE IS AT LEAST A VERY MINOR CONCERN THAT TEMPERATURES COULD BE
COLD ENOUGH TO WORRY ABOUT WINTRY PRECIP TYPES. AT THIS POINT I CAN
FIND NO EXPLICIT OPERATIONAL MODEL GUIDANCE THAT DEPICTS WINTRY
PRECIP IN OUR CWA...OR EVEN ANY VIABLE ANALOGS (USING CIPS) SHOWING
SUCH. HOWEVER...THE GENERAL UPPER LEVEL PATTERN IS SOMETIMES
CONDUCIVE FOR PRODUCING BOUTS OF WINTRY WEATHER AROUND THESE PARTS
AND WE WILL HAVE TO WATCH THE EVOLUTION OF MODELS REGARDING THIS TIME
PERIOD PRETTY CLOSELY OVER THE NEXT FEW DAYS.

[Weather4LA]

Larry Cosgrove's take on this event:

http://www.examiner.com/article/holiday-we...iday-12-28-2012

[Mid Tn. Man]

Not very excited,NAO is almost neutral,ridging,no 50/50,it does give alot a drought areas much needed rain,looks OTS,yes it could change

[Mid Tn. Man]

After this system the SE will torch for a few days with a pattern change,to early to tell but the GFS seems to be sniffing another severe threat down the road,looks to familiar to the last one we had

[winterwarlock]

After this system the SE will torch for a few days with a pattern change,to early to tell but the GFS seems to be sniffing another severe threat down the road,looks to familiar to the last one we had

If I Remember Right...the GFS Recently had those Same Days At or Below Normal in Temps and then Trended to this Predicted Warm Pattern? We can only hope it Trends back to more Seasonal Temps?

[Mid Tn. Man]

No hope for this storm,About East,foward march !!Welcome to the Atlantic !!

[Mid Tn. Man]

0Z euro goes OTS,The Nam shows its phasing at the end of its run but that serves no purpose,the SJ as strong as it is would destroy the phase.Nice rain for drought areas though.

[Mid Tn. Man]

One good thing about around these dates is N/FL,S/GA gets some much needed drought help.On the GFS 18z,it trains rain through this area from h60-h120

[winterwarlock]

One good thing about around these dates is N/FL,S/GA gets some much needed drought help.On the GFS 18z,it trains rain through this area from h60-h120

The Canadian Global GGEM shows something Interesting around the 102z-108z Time Frame?:

[Mid Tn. Man]

The Canadian Global GGEM shows something Interesting around the 102z-108z Time Frame?:

Probably nothing,remember you are looking at precip falling 6 hrs before with these charts,more than likely its dry what you are showing 18z,0z

[swilliams1005]

Probably nothing,remember you are looking at precip falling 6 hrs before with these charts,more than likely its dry what you are showing 18z,0z

It takes a miracle for snow in eastern NC looks like this one is another rain event for me, go figure!

[Mid Tn. Man]

It takes a miracle for snow in eastern NC looks like this one is another rain event for me, go figure!

Pattern will flip soon,just get ready for about a 10 day warmup soon

[ShawnEastTN]

Pattern will flip soon,just get ready for about a 10 day warmup soon

Oddly enough, and unexpected due to the amount of WAA coming, I'm seeing sleet IMBY in East TN. I'm a little leery as 2 nights ago we weren't forecast to get snow showers, but got a dusting. I have not seen any wind but expected a south wind today to jumpstart WAA, i'm sure the upper levels its occurring but there must still be a shallow layer of below freezing air left that hasn't been routed yet by WAA.

[ShawnEastTN]

Oddly enough, and unexpected due to the amount of WAA coming, I'm seeing sleet IMBY in East TN. I'm a little leery as 2 nights ago we weren't forecast to get snow showers, but got a dusting. I have not seen any wind but expected a south wind today to jumpstart WAA, i'm sure the upper levels its occurring but there must still be a shallow layer of below freezing air left that hasn't been routed yet by WAA.

Dew point IMBY 25... Air temp 40 after having risen to 45 a couple hours ago. Evaporational cooling occurring IMBY.

[Mid Tn. Man]

GFS 0z shows a weak system going into the mountains,Tn./NC about hr 30,should be good enough to spit some snow,radio cooling should help out