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January 17th-18th Winter Storm Discussion


BullCityWx

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since we have many who live in Western NC frequenting this board (Franklin, Don, Met and others)... I'm pulling for them and expect to see a tad more expansive precip field on radar on the northern side of this system compared to what is currently shown on the GFS and Euro

 

although, the heaviest precip will certainly be under the upper low and highest vertical velocities... so being too far north in Western NC might not be as good of a position in this case

 

Balsam Mountains to Cataloochee are my pick to click

 

Thanks Andy, long way to go with more twists & turns I'm sure. People get sick of hearing about the Mnts getting snow, but it hasn't been a bed of roses here. I know 85 & the Boone boys have had some good ones but it has been almost 2 yrs since I have seen anything over a 2" lay. I am not complaining but after 2009-2010, 2010-2011 it has been slim pickins.

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We shall see.  The NAM soundings indicate change-over to snow by 4pm and quickly ending by 10pm.  Gotta figure the first hour or two of any potential snow will be working as a foundation builder for more accumulations.  My first guess for AVL is 2-4", again using essentially a blend of the NAM and EURO.  GFS is about 200 miles further south with the low than the NAM, so big changes are still possible.  In addition, the 06Z run of the GFS had no QPF over the western NC mountains, and now we are "back on " again with the 12Z run.  And we are within 48-60 hours of the event starting!

 

GFS soundings, FWIW, show changeover by 2pm, ending by 7pm.  Colder but drier is the end result there.  1-2" if you take it at face value.

 

If the 00Z and tomorrow's 12Z NAM/GFS start to converge, look for a WSW by noon tomorrow for the western NC mountains.

 

My winner?  Smoky Mountains National Park.  6"?

 

 

 

I think balsam gap can hit 6". I could see some 1' foot lollies in the park above 5000ft

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I thought it helps to be just north of the 700mb low? Is that not the best spot to be for the best rates?

 

yes, meant to type "under and to the nrthwest side of the middle and upper level core" which is also right in line with the north and northwestern side of the 700mb low

 

that's where the highest velocities will be in generating the heaviest precip

 

it would also REALLY help if we had a closed 850mb low in this situation to help wrap in some better mid-level cold, but that tilt negative at 500mb doesnt happen so no closed low at 850

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Thanks Andy, long way to go with more twists & turns I'm sure. People get sick of hearing about the Mnts getting snow, but it hasn't been a bed of roses here. I know 85 & the Boone boys have had some good ones but it has been almost 2 yrs since I have seen anything over a 2" lay. I am not complaining but after 2009-2010, 2010-2011 it has been slim pickins.

Same here Don, it's went from feast to famine in no time.

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good point brother

 

it pays to stay somewhat optimistic and looking at how things are trending knowing that a few minor changes can put you in the game... too bad this system has a bit of a low ceiling as to how cold the middle and upper levels can get in Charlotte Thursday evening

 

I'm not holding my breath on it that's for sure...but I think Jeremy (QueenCityWx) also brought up an ULL that went through GA. I believe that was also around Feb or March or 2010. IIRC it was supposed to be marginal and really overperformed. IMHO these are the ones that have the highest element of surprise, so I'll just hope for the best.....well at least until the new NAM comes out lol. 

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since we have many who live in Western NC frequenting this board (Franklin, Don, Met and others)... I'm pulling for them and expect to see a tad more expansive precip field on radar on the northern side of this system compared to what is currently shown on the GFS and Euro

 

although, the heaviest precip will certainly be under the upper low and highest vertical velocities... so being too far north in Western NC might not be as good of a position in this case

 

Balsam Mountains to Cataloochee are my pick to click

 

 

We shall see.  The NAM soundings indicate change-over to snow by 4pm and quickly ending by 10pm.  Gotta figure the first hour or two of any potential snow will be working as a foundation builder for more accumulations.  My first guess for AVL is 2-4", again using essentially a blend of the NAM and EURO.  GFS is about 200 miles further south with the low than the NAM, so big changes are still possible.  In addition, the 06Z run of the GFS had no QPF over the western NC mountains, and now we are "back on " again with the 12Z run.  And we are within 48-60 hours of the event starting!

 

GFS soundings, FWIW, show changeover by 2pm, ending by 7pm.  Colder but drier is the end result there.  1-2" if you take it at face value.

 

If the 00Z and tomorrow's 12Z NAM/GFS start to converge, look for a WSW by noon tomorrow for the western NC mountains.

 

My winner?  Smoky Mountains National Park.  6"?

 

Queue the crazy guy with a fedora and cigar hanging from his mouth - fist full of dollars and shouting to the suddenly raucous crowd for bets (there's always a lot of smoke in these scenes too)...

 

I think somewhere between Brevard and Sylva have a shot to close the deal.

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GSP's afternoon short term:

 

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 225 PM TUESDAY...THE NAM AND GFS ARE COMING INTO BETTER
AGREEMENT IN THE TRACK OF THE SRN STREAM LOW THAT AFFECTS THE REGION
ON THURSDAY. BY 00 UTC FRI THE NAM HAS THE CENTER OF THE UPPER LOW
NEAR ANDERSON...WHILE THE GFS HAS IT ONLY ABOUT 50 TO 75 MILES
FURTHER SOUTH.
THE GFS CONTINUES TO EXHIBIT CONSIDERABLY MORE TILT
WITH THE SYSTEM AS IT HAS THE SFC LOW JUST EAST OF SAVANNAH AT 18
UTC THU WHILE THE NAM/S SFC REFLECTION IS SOMEWHERE BETWEEN COLUMBIA
AND GREENWOOD. GFS IS NOW DEVELOPING A CONSIDERABLE ABOUT OF PCPN
ALONG AND NORTH OF THE TRACK OF THE H5 LOW. THE NAM HAS BEEN WET AND
CONTINUES TO BRING ABUNDANT PCPN TO JUST ABOUT THE ENTIRE FA ON
THURSDAY. THE GFS/S HEAVIEST RAIN FALLS OVER NE GA...THE UPSTATE AND
THE SRN NC PIEDMONT. HOWEVER...IT STILL HAS ANYWHERE FROM A QUARTER
INCH OF LIQUID ALONG THE TN LINE TO NEARLY AN INCH OF LIQUID
EQUIVALENT OVER THE SE SLOPES OF THE BLUE RIDGE.


THE AIRMASS WILL INITIALLY BE QUITE WARM. EVEN AS PCPN WILL START
WEDNESDAY NIGHT...H8 TEMPS FALL ONLY TO AROUND +3 DEG C ON THE GFS
NEAR THE TN LINE BY MORNING. THE NAM IS EVEN WARMER. AS STRONGER
LIFT DEVELOPS AROUND 12 UTC...PROFILES MOISTEN AND BECOME MORE
ISOTHERMAL. EVENTUALLY RAIN SHOULD CHANGE TO SNOW ACROSS THE HIGHER
MTN ELEVATIONS...STARTING NEAR THE TN LINE AND PROGRESSING EASTWARD
DURING THE COURSE OF THE DAY. THE SREF PLUME DIAGRAMS NOW HAVE A
MEAN SNOWFALL TOTAL OF 3.8 INCHES AT ASHEVILLE DURING THE DAY ON
THURSDAY. I HAVE SEEN THE PLUME DIAGRAMS RUN COLD DURING A COUPLE
EVENTS ALREADY THIS WINTER...AND I/M NOT SURE HOW EASY IT WILL BE TO
COOL TO THE VALLEY FLOORS WITH THIS EVENT.
I IMAGINE THAT SNOW
LEVELS WILL GENERALLY RUN AT OR ABOVE 3000 FEET. HOWEVER...A GREAT
DEAL STILL DEPENDS ON HOW STRONG THE UPPER LOW IS. STRONGER UVV/S
COULD DRIVE SNOW LEVELS DOWN AS SEEN ON THE 12 UTC NAM BUFKIT
SOUNDING AT KAVL. WEAKER FORCING...IMPLIED BY THE 12 UTC
ECMWF/GFS...WOULD HAVE MORE TROUBLE DRIVING DOWN SNOW LEVELS
.

I USED AN SREF/GFS BLEND FOR THE QPF. THIS IS A LITTLE LOWER THAN
HPC/S...BUT IS STILL MUCH WETTER THAN THE PREVIOUS FORECAST. I USED
THE GFS THERMAL FIELDS TO RUN THE TOP DOWN TOOL FOR PCPN TYPE. THIS
GIVES ME 2 TO 3 INCHES OF SNOW...WHICH FALLS DURING THE DAY ON
THURSDAY AT ELEVATIONS ABOVE 3500 FEET OVER THE SOUTHWEST AND
CENTRAL MOUNTAINS. AMOUNTS ARE A LITTLE LIGHTER ACROSS THE NRN
MTNS...GENERALLY 1 TO 2 INCHES...THOUGH THEY DO REACH THE VALLEY
FLOORS. THIS IS A FOURTH PERIOD EVENT...AND AMOUNTS ARE CURRENTLY
BELOW WARNING CRITERIA. THEREFOR I WON/T ISSUE A WINTER STORM WATCH
WITH THIS PACKAGE. HOWEVER...GIVEN THE CURRENT TRENDS...A WATCH
ISN/T OUT OF THE QUESTION WITH LATER PACKAGES.


OUT ACROSS THE FOOTHILLS AND PIEDMONT ACCUMULATING SNOW CHANCES ARE
MUCH LOWER. THIS IS OWNING TO THE WARM LLVL AIRMASS EAST OF THE MTNS
AND WELL AS WARM GROUND TEMPERATURES. IF THE NAM/S STRONGER
DEFORMATION ZONE VERIFIED...THEN A PERIOD OF HEAVIER SNOW COULD
CERTAINLY AFFECT PARTS OF THE NC FOOTHILLS AND PIEDMONT.

HOWEVER...THIS FORECAST IS PREDICATED UPON THE BELIEF THAT THE NAM
CONTINUES TO BE A LITTLE TOO STRONG WITH THIS SYSTEM. THE
ECMWF/GFS/SREF SEEM TO BARE THIS OUT.

 

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Raleigh, NC NWS says "no snow for you"...

 

HAZARDOUS WEATHER OUTLOOKNATIONAL WEATHER SERVICE RALEIGH NC1229 PM EST TUE JAN 15 2013NCZ008>010-023>026-038>041-073>076-161730-GRANVILLE-VANCE-WARREN-ALAMANCE-ORANGE-DURHAM-FRANKLIN-DAVIDSON-RANDOLPH-CHATHAM-WAKE-STANLY-MONTGOMERY-MOORE-LEE-1229 PM EST TUE JAN 15 2013THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL NORTH CAROLINA..DAY ONE...THIS AFTERNOON AND TONIGHT.AREAS OF DENSE FOG ARE PROBABLE TONIGHT THROUGH EARLY WEDNESDAY..DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.A WEAK LOW PRESSURE SYSTEM WILL DEVELOP FROM THE GULF OF MEXICOTO OFFSHORE THE SOUTHEAST US COAST LATE THURSDAY AND THURSDAYNIGHT. PRIMARILY A COLD RAIN WILL ACCOMPANY THIS SYSTEM OVERCENTRAL NC...THOUGH THERE REMAINS A LOW PROBABILITY OF A BRIEFMIX WITH A LITTLE WET SNOW BEFORE THE PRECIPITATION COMES TO AN ENDTHURSDAY NIGHT. NO ACCUMULATION IS EXPECTED...GIVEN BOTH THEBREVITY OF ANY SUCH OCCURRENCE...AS WELL AS PRECEDING WARM GROUNDAND ABOVE FREEZING SURFACE TEMPERATURES.
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Hmmmm....I know it says "snowfall" that those #s look like total precip values. 

 

There will be many disappointed by this system and a few very happy......

LOL that is a terrible map with liquid type amounts given with hundreths. I would like to see the 60+ contour show up one day ;).

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GSP's afternoon short term:

 

 

 

IF THE NAM/S STRONGER

DEFORMATION ZONE VERIFIED...THEN A PERIOD OF HEAVIER SNOW COULD

CERTAINLY AFFECT PARTS OF THE NC FOOTHILLS AND PIEDMONT.

HOWEVER...THIS FORECAST IS PREDICATED UPON THE BELIEF THAT THE NAM

CONTINUES TO BE A LITTLE TOO STRONG WITH THIS SYSTEM. THE

ECMWF/GFS/SREF SEEM TO BARE THIS OUT.

 

out to 42 hours... newest 18z NAM weaker at 500mb compared to the 12z version... weakening trend definitely occuring and will probably go toward the GFS as far as vorticity energy... but heavy precip rates are still probable

 

at least the heavy rates provide some optimism in some dynamic cooling outside of Western NC high country

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IF THE NAM/S STRONGER

DEFORMATION ZONE VERIFIED...THEN A PERIOD OF HEAVIER SNOW COULD

CERTAINLY AFFECT PARTS OF THE NC FOOTHILLS AND PIEDMONT.

HOWEVER...THIS FORECAST IS PREDICATED UPON THE BELIEF THAT THE NAM

CONTINUES TO BE A LITTLE TOO STRONG WITH THIS SYSTEM. THE

ECMWF/GFS/SREF SEEM TO BARE THIS OUT.

 

out to 42 hours... newest 18z NAM weaker at 500mb compared to the 12z version... weakening trend definitely occuring and will probably go toward the GFS... but heav precip rates are still probable

Interestingly enough it looks colder at the sfc.

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The timing of this thing is really what's gonna hurt folks in NC I'd wager...not good that the onset is coming in the afternoon. It's weaker but colder. Mountains are money on this run. You can see on this run it's trying to phase with some northern energy...nothing huge but that could be why temps are better at the sfc. 

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