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Feb 12-13 Sleet/Snow/ZR Event


JoshM

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Kilm, Ever/Always conservative ,,, Mention(s) a possibility OF *Wintery Precipitation*...

Quite a few People have mentioned the analog from 1988...,, Which, I defiantly wouldn't mind, Here in Wilmington, We received several inches from that event in 88..  

 

 Long term /Tuesday through Friday/...
as of 3 am Saturday...chances for rain increase as Tuesday wears on
due to weak low pressure developing on frontal boundary well off the
coast. Tough to say whether there is a short break Tuesday night
before the next system takes shape in similar location. This looking
rather important as temperature profiles seem supportive of at least some
wintry ptype. The GFS has backed off in its depiction of this system
benefiting from Gomex moisture while the European model (ecmwf) still looks fairly
wet. Also fairly new is the much slower timing in the GFS showing
the best chance for rain not until Thursday. Will stick more in line
with previous forecast due to support from European model (ecmwf) but show very low rain
chances on Thursday.

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CAE took the central midlands out of their discussion

 

 

.SHORT TERM /7 AM SUNDAY THROUGH MONDAY NIGHT/...
HIGH PRESSURE WILL CONTINUE BUILDING IN TO THE NORTHERN PLAINS
SUNDAY AND INTO THE WESTERN GREAT LAKES BY MONDAY NIGHT. THIS WILL
PUSH THE FRONTAL BOUNDARY WHICH HAS BEEN NORTH OF THE FORECAST
AREA SOUTHWARD AND INTO THE AREA MONDAY. THIS WILL RESULT IN
INCREASING CLOUDS THROUGH SUNDAY NIGHT AND MONDAY WITH RAIN
EXPECTED TO BEGIN IN THE WESTERN MIDLANDS MONDAY AFTERNOON AND
OVER THE REMAINDER OF THE AREA MONDAY NIGHT. MAIN FOCUS WILL BE
THE NORTHERN MIDLANDS WHERE COLDER AIR WILL RESIDE CREATING THE
POTENTIAL FOR A MIX OF RAIN AND SNOW. MODELS DIFFER ON THE AMOUNT
OF COLD AIR...HOWEVER CONFIDENCE IN POTENTIAL FOR SNOW IS
INCREASING. CURRENTLY EXPECT MIX OF RAIN AND SNOW TO REMAIN NORTH
OF THE CAE AREA WITH NO ACCUMULATION CURRENTLY EXPECTED.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
MODELS ARE IN GOOD AGREEMENT SYNOPTICLY THROUGH THE LONG TERM
WITH DIFFERENCES IN TIMING AND INTENSITY DIFFERENCES FROM
WEDNESDAY THROUGH SATURDAY. LONG WAVE TROUGH WILL REMAIN OVER THE
EASTERN US THROUGH THE PERIOD WITH THE UPPER LEVEL PATTERN
REMAINING PROGRESSIVE ALLOWING A COUPLE OF SYSTEMS THROUGH THE
AREA BY NEXT SATURDAY. MAIN FOCUS OF THE LONG TERM WILL BE TUESDAY
AND WEDNESDAY WHEN THE POTENTIAL FOR A WINTRY MIX OVER THE
NORTHERN AND WESTERN MIDLANDS EXITS. MODELS CONTINUE TO DIFFER ON
THE AMOUNT OF COLD AIR WITH THE SYSTEM AND A COUPLE DEGREES EITHER
WAY WILL MAKE A LARGE DIFFERENCE. DUE TO UNCERTAINTY HAVE REMAINED
WITH A MIX OF RAIN AND SNOW MAINLY OVER THE NORTHERN MIDLANDS FOR
TUESDAY AND TUESDAY NIGHT...WHICH WILL FINALLY END AS TEMPERATURES
WARM WEDNESDAY MORNING. FOR WEDNESDAY ONWARD MODELS DIFFER WITH
THE TIMING OF SYSTEMS WITH THE GFS BEING FASTER TO EJECT THE
SYSTEM WHILE THE ECMWF DEVELOPS A LOW JUST OFFSHORE OF SC. WITH
THE DIFFERENCES IN MODELS HAVE MADE FEW CHANGES TO THE FORECAST
FOR THURSDAY AND BEYOND. TEMPERATURES THROUGH THE LONG TERM WILL
BE BELOW NORMAL TO BEGIN THE PERIOD THEN WARM TO ABOVE NORMAL BY
SATURDAY.

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1. a. The 12Z Ukie is textbook major storm for N/C GA, most of SC incl. maybe CHS, and S NC. In Ga, it appears it would give major IP to ATL/Tony/Delta/MCN, major S to AHN/Lookout, and major ZR south of Delta/MCN (850's only +2) on TUE mainly after 12Z looking at 700 RH/850's at hour 72/sfc. It may even bring some ZR to as far as SAV, where 850's are down to +4 C! I have a feeling the Ukie is too cold at 850 since it is colder than other models. Perhaps it has a bit of a cold bias at 850?? Anyone know?

 

 b. Then, looking at their 96 hour sfc map with a well defined low near N.O. and great wedging, the implication is that there'd be a 2nd wave of precip. that would continue the precip. into Wed. (likely more Zr then). I don't have qpf past 72, which is often underdone on the Ukie.

 

2. The 12Z JMA looks similar to the 12Z Euro with two waves of sig. wintry precip. for GA/SC.

 

In summary for GA at least, 5 of the 6 12Z models (Euro, Ukie, CMC, JMA, NAM) have sig. wintry precip for N GA on Tue and likely down to Delta on 4 of the 6. 4 of the 6 (not NAM) have a major storm for N GA and probably down to Delta. But as Tony wonders, where is the Goofy?

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oh sweet!  thank you very much

Yeah, Chris, it was mostly sleet here with some snow, and zr, but not enough for tree damage.  I don't remember losing power.  We also had a big honking z storm in the 80's that left us without power for 10 days.  Well over an inch of zr, so there were so many limbs down I couldn't see the ground for over an acre.  Huge bon fires for weeks after, so I really want this to go sleet most of the event :)  And, actually that's that last bad one i've seen around here..the rest have been mostly nuisance events, but after Atl in 73 and the one mentioned above, anything under an inch of zr seems like a light weight event to me now, lol.  T

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I think RAH says it best...

~snippet~

DESPITE SIGNIFICANT DIFFERENCES AMONG THE LONG RANGE MODELS...THERE

IS RELATIVELY GOOD AGREEMENT THAT AN ARCTIC AIRMASS WILL ADVECT INTO

CENTRAL NC LATE MON/MON NIGHT...AND THAT A MILLER-A TYPE CYCLONE

SHOULD DEVELOP IN VICINITY OF A STRONG BAROCLINIC ZONE ALONG OR

OFFSHORE THE CAROLINA COAST TUE/WED. HOWEVER...FORECAST SPECIFICS

REMAIN ELUSIVE...AND IT IS DIFFICULT TO SAY MORE THAN 1) CENTRAL NC

SHOULD SEE BELOW NORMAL TEMPERATURES EARLY/MID NEXT WEEK AND 2)

THERE WILL BE A CHANCE FOR WINTRY PRECIPITATION OVER AT LEAST SOME

(IF NOT ALL) OF CENTRAL NC BETWEEN TUE MORNING AND WED NIGHT. IN

SUCH A PATTERN...IT WOULD BE UNWISE TO ACCEPT ANY MODEL SOLUTION AT

FACE VALUE 72+ HRS OUT. SIMILARLY...ANY ASSERTION RELATING TO

PTYPE/ACCUM/IMPACT IS SIMPLY BEYOND THE SCIENCE AT THIS TIME...AND

ANY STATEMENT TO THAT END WOULD BE SPECULATION AT BEST. -VINCENT

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18z NAM rolling in... looks very similar to 12z but it's too early to say it'll stay that way.

 

Out to 48 a bit different at 5h. Energy out west is strong with not as many vorts floating around east of it. Not sure I like that northern energy floating around MT. Nice strong 1036 high in the central US though. 

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Quite a good read from KGSP in the Afternoon AFD

AFDGSP

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC

258 PM EST SAT FEB 8 2014

.SYNOPSIS...

HIGH PRESSURE WILL REMAIN OVER THE AREA THROUGH THE WEEKEND. A COLD

AND MOIST PATTERN WILL THEN SET UP ACROSS THE REGION MONDAY AND

REMAIN THROUGH THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /THROUGH SUNDAY/...

AS OF 200 PM EST SATURDAY...A SOUTHERN STREAM SHORT WAVE WILL

QUICKLY TRANSLATE EASTWARD OVER THE NEXT 24 HOURS...MOVING FROM

WESTERN KANSAS THIS MORNING...TO A POSITION OVER CENTRAL SOUTH

CAROLINA BY SUNDAY MORNING. THE WAVE WILL BE LARGELY DRY...THOUGH

THERE SHOULD BE AN INCREASE IN MID-LEVEL MOISTURE BY LATE TONIGHT.

AS THE WAVE PASSES...INCREASED MIXING AND A STRENGTHENING LEE SIDE

TROUGH SHOULD RESULT IN BREEZY CONDITIONS ACROSS THE PIEDMONT DURING

THE AFTERNOON HOURS...WITH WINDS GUSTING UP TO 25 MPH OVER THE

UPSTATE...NE GA AND THE SRN NC PIEDMONT. THIS WILL ALSO HELP TO PUSH

TEMPERATURES UP TO 60 DEGREE IN MANY LOCATIONS OUTSIDE THE MOUNTAINS.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...

AS OF EARLY SAT AFTN...SUNDAY NIGHT A WEAK TROUGH DRAGS THRU THE

UPPER OHIO VALLEY ENHANCING LLVL MOISTURE OVER EAST TN...WITH

GENERALLY WESTERLY FLOW ACRS THE SRN APPALACHIANS UNDER VERY BROAD

ERN CONUS TROUGH. WEAK UPSLOPE FORCING MAY DRIVE SOME LIGHT SHOWERS

ALONG THE TENN BORDER EARLY MONDAY. TEMPS SUPPORT SNOW MAINLY IN

HIGHER ELEVATIONS BUT GIVEN THE SHALLOW MOISTURE ACCUMS SHOULD BE

MINIMAL.

MEANWHILE...SPRAWLING HIGH PRESSURE BUILDS OUT OF THE PLAINS AS THE

WEAK TROUGH SAGS SOUTHWARD THRU THE TENN VALLEY. THERMAL GRADIENT

AMPLIFIES AND LLVL FRONTOGENESIS STRENGTHENS THRU THE DAY MON AND

INTO MON NIGHT...WITH WAA AND ISENTROPIC UPGLIDE PEAKING TUESDAY OVER

THE CWFA. UPPER TROUGH AMPLIFIES SLIGHTLY WITH EMBEDDED SHORTWAVE

MOVING OVERHEAD AT THAT TIME ALSO. MODELS SHOW SOME DIFFERENCES

BEGINNING MONDAY REDUCING CONFIDENCE FROM THAT POINT FORWARD...WITH

THE NAM APPEARING MOST BULLISH WITH FRONTOGENETIC FORCING AND MOVING

THE BEST THEREOF OVER THE SRN FA BY TUESDAY. GFS FEATURES A MUCH

WEAKER BOUNDARY AT THE SAME TIME. EC SHOWS MORE BROAD WARM ADVECTION

SETTING UP MON NIGHT...CLOSER TO THE NAM THAN THE GFS BUT NOT

NECESSARILY FOLLOWING IT EXACTLY. NAM DOES RESOLVE A WAVE ALONG THE

BOUNDARY AT 850MB...THIS LIKELY RELATED TO ITS TIGHTER GRADIENT. CMC

LEANS IN FAVOR OF A MORE NAM/EC LIKE SOLUTION. THE CONSENSUS FROM

THESE THREE WOULD BE FOR A WETTER AND COLDER FORECAST FOR TUE AS WARM

UPGLIDE CONTINUES OVER ARCTIC AIR PUSHING IN AT THE SFC IN A

WEDGELIKE SCENARIO. TUESDAY/S PRECIP NOW LOOKS TO BE A SEPARATE EVENT

FROM THE EVENT LATER IN THE WEEK.

NAM IS THE WETTEST MODEL WITH WELL OVER 1 INCH OF LIQUID QPF OVER

MOST OF THE FA THROUGH 00Z WED WHEN IT TAPERS QPF OFF. EC IS NOT FAR

BEHIND BUT MORE GRADUALLY BUILDS UP TO AROUND 1 INCH MAX BY TUE

NIGHT. SREF PLUMES INDICATE THE 06Z NAM WAS AN OUTLIER WITH MOST OF

ITS MEMBERS BEING SUBSTANTIALLY LESS AND THEREFORE A MUCH MORE BENIGN

MEAN RUN TOTAL AROUND A THIRD OF AN INCH THRU 00Z WED. MAINTAINING

ONLY MODERATE CONFIDENCE...HAVE UPPED POPS TO LIKELY MORE OR LESS

ALG/SOUTH OF I-85 ON TUE BUT KEPT QPF LOW ENOUGH TO KEEP SNOW ACCUMS

IN EVENTUAL ADVISORY RANGE. EARLY IN THE EVENT LATE MON...AS TEMPS

DROP BELOW FREEZING OVER THE PIEDMONT...THERE LOOKS TO BE ENOUGH OF A

WARM NOSE THAT SOME AREAS COULD SEE FREEZING RAIN...BUT PROG

SOUNDINGS COOL THEREAFTER TO EXPECT ALL RAIN OR SNOW DEPENDING ON SFC

TEMPS. WET BULB EFFECT SHOULD KEEP TEMPS DOWN DURING THE DAY TUE AND

LIKELY LEAD TO A NONDIURNAL TREND.

EXCEPT FOR THE EC...WHICH HOLDS ON TO WEAK LIFT AHEAD OF COASTAL LOW

DEVELOPING WED...MODELS WEAKEN BAROCLINIC ZONE TUE NIGHT AND POPS AND

QPF THUS DIMINISH SOMEWHAT. WITH MID-UPPER DRYING SUGGESTED...THERE

IS A POSSIBILITY FOR PRECIP TO CHANGE FROM SNOW TO FZRA WITH LOSS OF

NUCLEI DESPITE SOUNDINGS REMAINING SUBFREEZING...BUT WITH LOW

CONFIDENCE WILL KEEP AN ALL RA/SN FORECAST AT THAT TIME.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...

AS OF 230 PM EST SATURDAY...THE EXTENDED RANGE PERIOD BEGINS

WEDNESDAY MORNING WITH A STRONG ARCTIC HIGH IN PLACE ACROSS THE

NORTHEAST LEADING TO A DEEP CAD WEDGE EXTENDING THROUGH THE SOUTHERN

APPALACHIANS. SURFACE CYCLONE OVER THE NORTHERN GULF WILL BEGIN TO

MOVE ONSHORE ACROSS THE FL PANHANDLE. WA/MOISTURE ADVECTION WILL BE

ONGOING ACROSS THE SOUTHEAST WITH ISENTROPIC ASCENT OCCURRING

ATOP THE ABOVE MENTIONED WEDGE. A WINTRY MIX OF SLEET/SNOW REMAINS

A POSSIBILITY ACROSS THE SOUTHERN MOST ZONES INTO LATE WEDNESDAY

MORNING ASSOCIATED WITH H85 WARM FRONTAL ISENTROPIC ASCENT.

ELSEWHERE IT LOOKS AS IF THERMAL PROFILES WILL SUPPORT ALL SNOW

THROUGH THE LATE MORNING HOURS.

MEANWHILE...OTHER THAN CONSENSUS ON MILLER A STORM TYPE...GUIDANCE

REMAINS IN DISAGREEMENT WITH THE ECMWF/CMC REMAINING CONSISTENT WITH

PREVIOUS RUNS...AND GFS BEING SLOWER AND WARMER WITH THE OVERALL

PATTERN. AT THIS POINT DECIDED TO LEAN HEAVILY ON THE ECMWF/CMC

SOLUTIONS WHICH INDICATE WARMING TEMPERATURES BOTH ALOFT DUE TO H85

WARM FRONTAL INTRUSION...AND AT THE SURFACE DUE TO DIURNAL EFFECTS

THROUGH THE DAY ON WEDNESDAY. EXPECTING PRECIPITATION TO CHANGE

OVER TO ALL RAIN THROUGH THE REMAINDER OF THE DAY ALONG AND SOUTH OF

THE I40 CORRIDOR WITH A RAIN SNOW MIX REMAINING A POSSIBILITY NORTH

OF I40. PRECIPITATION WILL LIKELY REMAIN IN THE REGION OVERNIGHT

THURSDAY WITH TEMPERATURES COOLING TOO NEAR/BELOW FREEZING LEVELS

ACROSS MOST OF THE CWFA WITH THE COOLER TEMPERATURES RESIDING NORTH

OF THE I85 CORRIDOR. FREEZING RAIN WILL BECOME A CONCERN ACROSS

THESE ZONES OVERNIGHT INTO THURSDAY MORNING. WITH THAT SAID...QPF

REMAINS QUITE LOW AT THAT TIME AS THE BETTER MOISTURE AXIS SETS UP

TO THE SOUTH OF THE FAVORABLE FREEZING RAIN SUPPORTIVE AIRMASS.

THUS...NOT EXPECTING ANY SIGNIFICANT ICE ACCUMULATIONS DURING THIS

TIME FRAME. ANY SHIFT NORTHWARD OF THE ABOVE MENTIONED MOISTURE

AXIS COULD RESULT IN INCREASED ICE ACCUMULATIONS...BUT AS OF NOW

THIS DOES NOT LOOK LIKELY AS MODEL TRENDS HAVE ACTUALLY INDICATED

SOUTHWARD MOVEMENT.

AS THE SURFACE CYCLONE AND UPPER WAVE EJECT TO THE NORTHEAST ON

THURSDAY MORNING...A BRIEF NWFS REGIME COULD DEVELOP ALONG THE HIGH

TERRAIN OF NC WITH NO SIGNIFICANT ACCUMULATIONS EXPECTED.

TEMPERATURES WILL MODERATE SOMEWHAT BY WEEKS END AS WEAK HIGH

PRESSURE SETS UP OVER THE WESTERN ATLANTIC ALLOWING FOR THE RETURN

OF SOUTHERLY FLOW AND MOSTLY SUNNY SKIES. LATE IN THE PERIOD...LONG

RANGE MODELS INDICATE ANOTHER UPPER WAVE AND ASSOCIATED COLD FRONT

DIVING THROUGH THE UPPER MIDWEST AND SWEEPING THROUGH THE SOUTHERN

APPALACHIANS NEXT WEEKEND. DUE TO RANGE AND UNCERTAINTY...DECIDED

NOT TO HIGHLIGHT ANYTHING MORE THAN SLIGHT CHANCE POPS IN THE

FORECAST.

&&

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Out to 48 a bit different at 5h. Energy out west is strong with not as many vorts floating around east of it. Not sure I like that northern energy floating around MT. Nice strong 1036 high in the central US though. 

 

It's a good thing. It's what enhances the precip across our area. Notice the precip breaking out over OK by 54.  Out to 54... looks to be another big hit coming for us.  Actually wetter at this hour compared to 12z.

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1. a. The 12Z Ukie is textbook major storm for N/C GA, most of SC incl. maybe CHS, and S NC. In Ga, it appears it would give major IP to ATL/Tony/Delta/MCN, major S to AHN/Lookout, and major ZR south of Delta/MCN (850's only +2) on TUE mainly after 12Z looking at 700 RH/850's at hour 72/sfc. It may even bring some ZR to as far as SAV, where 850's are down to +4 C! I have a feeling the Ukie is too cold at 850 since it is colder than other models. Perhaps it has a bit of a cold bias at 850?? Anyone know?

 

 b. Then, looking at their 96 hour sfc map with a well defined low near N.O. and great wedging, the implication is that there'd be a 2nd wave of precip. that would continue the precip. into Wed. (likely more Zr then). I don't have qpf past 72, which is often underdone on the Ukie.

 

2. The 12Z JMA looks similar to the 12Z Euro with two waves of sig. wintry precip. for GA/SC.

 

In summary for GA at least, 5 of the 7 12Z models (Euro, Ukie, CMC, JMA, NAM) have sig. wintry precip for N GA on Tue and likely down to Delta on 4 of the 7. 4 of the 7 (not NAM) have a major storm for N GA and probably down to Delta. But as Tony wonders, where is the Goofy?

I wondered that myself. I seem to remember it being too cold in the past but I'm not sure . Regardless, it's not too  much colder than the euro at 72 hours.  I know the gfs handles the system a bit differently than the uk but the gfs roughly has the 0c isotherm at roughly the same latitude at 72 hours too. Of course one has to consider that if the gfs is more aggressive like the rest of the models with the first wave it would be warmer. So take that one with a grain of salt. But comparing it to the euro, it's not so cold that it's unrealistic imo. It doesn't seem like much But those few miles can and will make a big difference for a lot of folks.

 

 

Euro

 

f72.gif

 

UK

 

f72.gif

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Looks like that polar energy swinging down from MT is pulling the initial wave a tad more north on the 18z NAM.  It's a lot drier on the gulf coast at 60.  HP is nosing into the NE a bit more as well... a bit colder at the surface in NC.

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I think RAH says it best...

...IT WOULD BE UNWISE TO ACCEPT ANY MODEL SOLUTION AT

FACE VALUE 72+ HRS OUT. SIMILARLY...ANY ASSERTION RELATING TO

PTYPE/ACCUM/IMPACT IS SIMPLY BEYOND THE SCIENCE AT THIS TIME...AND

ANY STATEMENT TO THAT END WOULD BE SPECULATION AT BEST. -VINCENT

Words of truth and wisdom from one of the best NWS offices around.

High repect for these guys. They are the ultimate pros in these situations.

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