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Jan 22-23 East Coast Storm Discussion

Wow

By Wow,
in Southeastern States

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Wow

Wow

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Posted

The NAM has a pretty potent warm nose in the 750-850 mb range which is hard to diagnose just looking at the 850 mb 0C charts.  You really need to look at soundings.

 

Nevertheless, a lot of areas do seem to hang onto snow for awhile (~18z tomorrow).  Good run.  The Triangle is below freezing throughout, as well.

 

I don't think the GFS had such a potent warm nose, so I am not sure if the NAM is just overdoing it or if it's picking up on something the lower-resolution GFS cannot.

 

ULL center is west of us per NAM

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Jon

Jon

Posted
Posted

Yea, NAM was the final nail in the coffin for me. I really don't buy all the ZR. This is probably going to be flipping between sleet and snow depending on rates. 

I have a pretty bad feeling Wake Co will get sleeted pretty gnarly and our totals will be hit hard.

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drfranklin

drfranklin

Posted
Posted

So my understanding is that freezing rain is self-limiting, especially if it's coming down heavily. GSP seems to allude to this in their discussion. Does anybody know how the math on this works? I'm guessing there are a ton of factors at work.

what does that mean "physical limit" - 1 inch of ice is catastrophic

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CherokeeGA

CherokeeGA

Posted
Posted

dang. I totally forgot about the flooding aspect of this storm. Flooding may be our biggest worry in the I-20 corridor. Forget snow and ice ! Not many people on here have talked about the flooding risk with this system. All the talk seems to be snow or ice.

 

Correct.  We're going to get a couple of inches of rain before this even thinks about switching over late tomorrow.  On top of all the rain we've already had, and the winds are coming.  Gonna be some trees down.

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packfan98

packfan98

Posted
Posted

NAM keeps trending colder and pushing more towards the GFS which tells me the NAM is not having a good handle on either the dynamics of the storm or the CAD. Make me feel like making a gold prediction for the CLT area. 

 

Don't make that gold/bold prediction!  We have seen too many times that any warm nose from any model will verify and cut snow totals.  I'm thinking a sleet fest.

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wxduncan

wxduncan

Posted
Posted

Latest Package From GSP Just Issued:

 

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 245 PM...MAJOR WINTER STORM REMAINS ON TRACK TO DEVELOP
TONIGHT AND CONTINUE THRU THE DAY FRIDAY. STRONG UPPER LOW PRESSURE
SYSTEM MOVES TOWARD THE AREA TONIGHT. SLY LOW LEVEL FLOW STRENGTHENS
AHEAD OF THIS SYSTEM BRINGING COPIOUS MOISTURE OVER THE AREA AND
INCREASING ISENTROPIC LIFT. TEMPS WILL FALL THRU THE COLUMN AS THE
ATMOS MOISTENS AND PRECIP BEGINS. EVEN THEN...PRECIP WILL BEGIN AS
ALL RAIN EXCEPT FOR ALL AREAS OUTSIDE OF THE NC MTNS AND FOOTHILLS.
PRECIP WILL BEGIN AS A WINTRY MIX ACROSS THE LATTER AREAS. PRECIP
WILL THEN QUICKLY TRANSITION SO SNOW AND SLEET IN THE LATTER AREAS
WITH THE SNOW/SLEET MIX IN AND CHANGE OVER SPREADING SOUTH AND EAST
AWAY FROM THE MTNS AFTER MIDNIGHT. THIS CHANGE OVER IS CAUSED BY
EVAPORATIVE COOLING THEN A STRONG BARRIER JET DEVELOPING IN RESPONSE
TO DEVELOPING COLD AIR DAMMING. THE BARRIER JET WILL BRING COLD AND
DRY AIR ACROSS MUCH OF THE AREA THRU DAYBREAK KEEPING PRECIP AS SNOW
OR SLEET FOR ALL BUT THE AREAS SOUTH OF A TOCCOA...ANDERSON TO
LAURENS LINE. THESE AREAS COULD SEE A BRIEF MIX...BUT SHUD SEE
MOSTLY RAIN. WITH GENERALLY LIGHT PRECIP AND WARMER TEMPS BEFORE
MIDNIGHT...DO NOT EXPECT ANY SIGNIFICANT ACCUMS DURING THAT PERIOD.
THAT CHANGES AFTER MIDNIGHT AS COLD AIR COMES RUSHING IN AND HEAVIER
PRECIP DEVELOPS. ONLY LIGHT ICE ACCRETIONS ARE EXPECTED AFTER
MIDNIGHT AS THE WINTRY PRECIP WILL BE MOSTLY FROZEN. HOWEVER...SNOW
AND SLEET WILL RAPIDLY ACCUMULATE...WITH 1 TO 2 INCHES POSSIBLE
ALONG THE I-85 CORRIDOR...2 TO 4 OVER THE I-40 CORRIDOR...AND
GENERALLY 4 TO 6 ACROSS THE MTNS...WITH LOCALLY HIGHER AMOUNTS...
EXCEPT OVER THE FAR WRN VALLEYS OF GRAHAM AND SWAIN WHERE WARMER
TEMPS MAY LINGER.

THE UPPER LOW MOVES INTO THE WRN CWFA BY LATE ON FRI. STRONG DEEP
LAYER Q-VECTOR CONVERGENCE MOVES IN...ALONG WITH STRONG UPPER
DIVERGENCE...LEADING TO WIDESPREAD STRONG DEEP LIFTING. A STRONG H85
JET MOVES IN AS WELL...KEEPING STRONG UPSLOPE FLOW AND ISENTROPIC
LIFT OVER THE AREA. THIS WILL ALSO BRING A VERY WARM AND RELATIVELY
DEEP WARM NOSE AS FAR NORTH AS THE I-85 CORRIDOR. THE WARM NOSE WILL
LEAD TO A CHANGE OVER TO FREEZING RAIN FOR THE I-85 CORRIDOR AND ERN
PIEDMONT OF THE UPSTATE. THE NON-MOUNTAIN PORTION OF THE UPPER
SAVANNAH RIVER VALLEY WILL BE TRICKY AS THEY WILL SEE WARMER TEMPS
THRU THE PERIOD. EVEN WITH THE STRONG BARRIER JET...THE WARM NOSE
WILL AFFECT THESE AREAS STRONGLY...AND THE NEARBY LAKES WILL KEEP
THE SFC TEMPS WARMER. HOWEVER...AS THE H85 JET MOVES EAST...THE WARM
NOSE WILL WEAKEN AND THE BARRIER JET WILL TAKE OVER BRINGING IN
COOLER TEMPS...ALLOWING PRECIP TO TRANSITION TO FREEZING RAIN. COULD
SEE UP TO A HALF INCH...POSSIBLY EVEN HIGHER...ALTHOUGH THAT WOULD
BE APPROACHING THE PHYSICAL LIMIT...ACROSS THE I-85 CORRIDOR AND ERN
UPSTATE PIEDMONT. THE UPPER SAVANNAH RIVER LOCATIONS WILL BE ON THE
BORDER OF A QUARTER INCH ACCUMS...BUT WILL ADD TO THE WARNING FOR
CONSISTENCY. THE LAKELANDS AND ELBERT COUNTY WILL NOT SEE MUCH
ICE...BUT WILL LIKELY SEE ENUF OF A MIX THAT AN ADVISORY IS
WARRANTED.

FOR THE I-40 CORRIDOR AND THE MOUNTAINS AND NC FOOTHILLS...A
DIFFERENT STORY DEVELOPS. THE WARM NOSE WILL BE NEARLY NON EXISTENT
ACROSS THE MTNS...BUT DOES MOVE INTO THE NC FOOTHILLS AND NW
PIEDMONT DURING THE AFTERNOON. EVEN OVER THESE LOCATIONS...THE WARM
NOSE IS NOT AS STRONG AS LOCATIONS FARTHER SOUTH. THEREFORE...THEY
WILL SEE MOSTLY SNOW IN THE MORNING WITH A CHANGE TO OR MIX WITH
SLEET FOR THE AFTERNOON. THE BLUE RIDGE AND ADJACENT MTNS WILL SEE
MOSTLY SNOW THROUGHOUT. THE TN BORDER AREAS WILL BE THE TRICKY
LOCATIONS WHERE TEMPS COULD WARM FARTHER AWAY FROM THE COLD AND DRY
BARRIER JET AND DEEPER COLD AIR. THIS MAY LIMIT ACCUMS IN THOSE
LOCATIONS. THAT SAID...THIS ENTIRE AREA LOOKS TO REMAIN SOLIDLY IN
WARNING CRITERIA SNOW AND/OR SLEET. THE LOCATIONS NEAR THE TN BORDER
COULD SEE SOME MINIMAL ICE...WITH UP TO A QUARTER INCH ACCRETION
SOUTH OF I-40 FROM CATAWBA EAST. AGAIN SNOW AND SLEET ARE THE BIGGER
STORY WITH AMOUNTS RANGING FROM 4 INCHES IN SERN ROWAN COUNTY TO A
FOOT OR MORE ALONG THE BLUE RIDGE. AMOUNTS COULD EXCEED 10 INCHES
IN THE LOWER ELEVATIONS OF THE NC FOOTHILLS DOWN ACROSS THE SC AND
NE GA MTNS AND INTO THE NC VALLEYS AWAY FROM THE BLUE RIDGE. LESSER
AMOUNTS ARE LIKELY IN THE LOWER VALLEYS OF GRAHAM AND WRN SWAIN
COUNTIES.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 200 PM THU...CYCLOGENESIS WILL BE IN PROGRESS AT 00Z SATURDAY
ALONG THE CAROLINA COAST...WITH THE PRIMARY LOW QUICKLY FILLING
AS IT CROSSES THE CWFA. CORE OF UPPER LOW WILL MOVE ACROSS THE
AREA OVERNIGHT INTO THE EARLY PART OF THE DAY...NAM SHOWING
THE SLOWEST PROGRESSION THEREOF. WHILE THE MOST IMPRESSIVE
UPPER DYNAMIC FORCING WILL BE TO OUR EAST...MODEL CONSENSUS
INDICATES DEEP Q-VECTOR CONVERGENCE WILL REMAIN OVER THE AREA
THRU MIDNIGHT OR SO. AS THE UPPER LOW MOVES OVERHEAD...LOW LEVEL
FLOW WILL GRADUALLY BACK...SHIFTING THE BEST WARM ADVECTION NORTH
AND EAST...THEN COOLING THE ENTIRE COLUMN FROM WEST TO EAST. SOME
SEMBLANCE OF A WARM NOSE WILL PERSIST OVER THE AREA UNTIL NEARLY
DAYBREAK SAT...WITH TEMPS HOVERING VERY NEAR IF NOT JUST BELOW
FREEZING THRU THE NIGHT /ANY EVAPORATIONAL COOLING IS EXPECTED TO
HAVE ALREADY PLAYED OUT/. ALL AREAS OUTSIDE THE MOUNTAINS SHOULD SEE
A TRANSITION BACK THRU WINTRY MIX TO ALL SNOW BY MORNING. A LONGER
PERIOD OF FZRA RESULTS OVER THE NC PIEDMONT GIVEN THE STRONGER
WARM NOSE...AND ANOTHER TENTH OF ICE MAY ACCUMULATE THERE. THE
UPSTATE IS MOST LIKELY TO SEE A SECOND ROUND OF ACCUMULATING
SLEET AND SNOW...THOUGH IF A DRY SLOT MOVES IN AS SOME OF THE
GUIDANCE SUGGESTS...NO ICE NUCLEI MAY BE AVAILABLE...IMPLYING
FZRA INSTEAD. ALL HAZARDS IN THE FRI-SAT PERIOD FALL UNDER THE
EXISTING W/W/A.

VORT LOBES ROTATING AROUND THE UPPER LOW WILL STILL HAVE A MODEST
AMOUNT OF MOISTURE TO WORK WITH SATURDAY. DESPITE THE LOW...LAPSE
RATES ARE RELATIVELY POOR ON ACCOUNT OF THAT MOISTURE. NONETHELESS
SCATTERED LIGHT SNOW SHOWERS WILL CONTINUE...TRANSITIONING TO RAIN
OVER THE UPSTATE WHERE TEMPS WARM INTO THE MID-UPPER 30S. WRAPAROUND
MOISTURE AND UPSLOPE NWLY FLOW WILL ALLOW -SHSN TO CONTINUE ALONG
THE TENN BORDER SATURDAY NIGHT...BEFORE DRY HIGH PRESSURE BUILDS
BACK IN SUNDAY. HEIGHTS REBOUND RATHER QUICKLY IN THE WAKE OF THE
DEPARTING TROUGH...HOWEVER ASSUMING THAT SOME SNOW COVER AND/OR
ACCUMULATED ICE WILL STILL BE PRESENT...I LEANED TOWARD THE LOW
END OF THE GUIDANCE SPECTRUM FOR MAX TEMPS SUNDAY. STILL THINK
MOST OF THE AREA WILL REACH THE 40S...PERHAPS NEAR 50 IN PARTS OF
THE UPSTATE.

&&

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Solak

Solak

Posted
Posted

Winter storm advisory has been upgraded to a WS Warning for the Eastern parts of RAH area not previously under the warning.

URGENT - WINTER WEATHER MESSAGENATIONAL WEATHER SERVICE RALEIGH NC327 PM EST THU JAN 21 2016.MAJOR WINTER STORM EXPECTED TO IMPACT CENTRAL NORTH CAROLINALATE TONIGHT INTO SATURDAY...NCZ027-042-085-086-088-220500-/O.UPG.KRAH.WW.Y.0002.160122T0500Z-160122T2300Z//O.EXB.KRAH.WS.W.0001.160122T0500Z-160122T2300Z/NASH-JOHNSTON-SCOTLAND-HOKE-CUMBERLAND-INCLUDING THE CITIES OF...NASHVILLE...RED OAK...SHARPSBURG...SPRING HOPE...SMITHFIELD...CLAYTON...SELMA...BENSON...LAURINBURG...RAEFORD...ROCKFISH...SILVER CITY...FAYETTEVILLE327 PM EST THU JAN 21 2016...WINTER STORM WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO 6 PMEST FRIDAY...THE NATIONAL WEATHER SERVICE IN RALEIGH HAS ISSUED A WINTER STORMWARNING...WHICH IS IN EFFECT FROM MIDNIGHT TONIGHT TO 6 PM ESTFRIDAY. THE WINTER WEATHER ADVISORY IS NO LONGER IN EFFECT.* ACCUMULATIONS...SNOW ACCUMULATION OF 1 TO 2 INCHES...ALONG WITH  AROUND A TENTH TO TWO-TENTHS OF AN INCH OF ICE.* TIMING...PRECIPITATION WILL BEGIN BRIEFLY AS A MIXTURE OF SNOW  AND SLEET LATE TONIGHT AND QUICKLY CHANGE TO FREEZING RAIN  FRIDAY MORNING. THE FREEZING RAIN WILL CHANGE TO RAIN BY EARLY  FRIDAY AFTERNOON.* IMPACTS...TRAVEL WILL BECOME SLICK LATER TONIGHT INTO FRIDAY...   THEN GRADUALLY IMPROVE BY LATE FRIDAY OR FRIDAY EVENING AS  THE TEMPERATURES WARM THROUGH THE 30S AND THE RAIN FALLS.* WINDS...NORTHEAST 10 TO 20 MPH WITH GUSTS UP TO 35 MPH WILL RESULT  IN DOWNED LIMBS AND POWER-LINES.PRECAUTIONARY/PREPAREDNESS ACTIONS...A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW...SLEET...AND ICE ARE EXPECTED OR OCCURRING. STRONG WINDS ARE ALSOPOSSIBLE.  THIS WILL MAKE TRAVEL VERY HAZARDOUS OR IMPOSSIBLE.A WINTER STORM WARNING FOR SLEET MEANS THAT A WINTER STORM SYSTEMIS IMPACTING THE AREA WITH SIGNIFICANT AMOUNTS OF SLEET. TRAVELIS LIKELY TO BE SEVERELY IMPACTED.&&$$NCZ011-077-220500-/O.UPG.KRAH.WW.Y.0002.160122T0500Z-160122T2300Z//O.EXA.KRAH.WS.W.0001.160122T0500Z-160123T2300Z/HALIFAX-HARNETT-INCLUDING THE CITIES OF...ROANOKE RAPIDS...DUNN...ERWIN...ANGIER...LILLINGTON327 PM EST THU JAN 21 2016...WINTER STORM WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO 6 PMEST SATURDAY...THE NATIONAL WEATHER SERVICE IN RALEIGH HAS ISSUED A WINTER STORMWARNING WHICH IS IN EFFECT FROM MIDNIGHT TONIGHT TO 6 PM ESTSATURDAY. THE WINTER WEATHER ADVISORY IS NO LONGER IN EFFECT.* ACCUMULATIONS...SNOW ACCUMULATION OF 1 TO 3 INCHES...ALONG  WITH AROUND ONE QUARTER OF AN INCH OF ICE.* TIMING...PRECIPITATION WILL BEGIN AS A MIXTURE OF SNOW AND SLEET  LATE TONIGHT AND CHANGE OVER TO FREEZING RAIN FRIDAY MORNING.  THE FREEZING RAIN WILL CHANGE TO RAIN BY EARLY FRIDAY AFTERNOON.* IMPACTS...TRAVEL WILL BECOME SLICK LATER TONIGHT INTO FRIDAY...   THEN GRADUALLY IMPROVE BY LATE FRIDAY OR FRIDAY EVENING AS  THE TEMPERATURES WARM THROUGH THE 30S AND THE RAIN FALLS.* WINDS...NORTHEAST 10 TO 20 MPH WITH GUSTS UP TO 35 MPH WILL  RESULT IN DOWNED LIMBS AND POWER-LINES.* TEMPERATURES...IN THE LOWER 30S.
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Jon

Jon

Posted
Posted

That's insane. I had two inches a few years ago and that felt like it was extremely rare. It's just if most of this is sleet it could be like 6 inches. 

I mean it's possible, just a hunch I have. I really have no idea where this is going to go for Wake Co. zr will be self limiting, trend towards all-snow is highly doubtful. mostly rain is doubtful to me as well, so it leaves IP...

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ekman

ekman

Posted
Posted

I've been in a 4 inch sleet storm, 80s in central NC.

 

I was just thinking about that storm, it was Jan 25-26, 1987. I remember it was the night of the Giants-Broncos Super Bowl, and it was a really fun storm. I had to drive to work the next morning, four inches of sleet was actually not that bad to drive in, all things considered.

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jburns

jburns

Posted
Posted

 My guess is they're referring to only a certain amount can truly freeze since it's falling so quickly, but I'm not sure. However the latest NAM is making me thing we may be looking at more of a sleet fest anyway. 

 

 If there is no source for sustained cold air advection, then the latent heat of freezing associated with freezing rain will gradually increase temperatures to the freezing point. Once temperatures reach 32 degrees, ice no longer accumulates. 

 

NWS

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