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Feb 12-13 Sleet/Snow/ZR Event


JoshM

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Is that considering latent heat release from IP or ZR?

 

Greg,

  There will be a fresh supply of cold air from NE winds throughout to combat any latent heat release from ZR freezing. I don't think that is even an issue with IP unless I'm mistaken.

 Anyhow, I'm saying that if there is a ZR for which the temp. hangs out at 31-32 for much of it for the coldest (I've read about many like that), that can easily be very bad on the trees/lines especially though roads may do ok outside of bridges. I've seen a few comments on occasion to the contrary. 1/1973 was like this and it was one of the worst ever! Ask Tony!

 I'm not saying that makes it the worst kind. I'm just saying it still can be very bad as per history.

 

edit: May not be able to post for a while..too busy.

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Verbatim it's 90% ice, not snow for RDU.  CLT/GSO/INT mostly snow, 8-10".  Like I said above, the SLP shifts east we get more snow, shifts more west, we get rain.

The TV guy in High Point says a 6-8" iis certainly possible. However, this far out it would be an unwise forecasts. Odds of that much snow are currently around 20-30%. Good chance that type of forecast would blow all credibility and trust.

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My interpretation of Euro for RDU.

 

1.2 inches of total QPF

 

Light dusting during day Tuesday, but band of snow stays south of Triangle during the day.

 

Light snow starts early Wednesday morning, looks like there is certainly 2-3 inches of snow through 1pm. Between 1-7pm we switch over most likely to sleet. So maybe 3-4 inches of snow, and then 0.3 inches of QPF in the form of sleet or maybe freezing rain through 7pm Wednesday. Then another 0.3 inches of QPF from 7pm Wed to 1am Thursday likely in the form of sleet or freezing rain. Ending probably around 1am Thursday.

 

Interestingly enough as the ECMWF cranks the low off the Capes, a wrap around band of snow moves in during the day on Thursday with additional 1-2 inches of snow on top.

 

So all toll, something like 3-4 inches of snow to start, 0.5-0.6 inches of QPF in the form of sleet or freezing rain, my guess is mostly sleet. then another 1-2 inches as the storm comes to a complete end Thursday.

4 to 6 inches of snow with ice. That would be a mess and create havoc on the roads. And of course there could be more snow if it keeps trending east.

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The TV guy in High Point says a 6-8" iis certainly possible. However, this far out it would be an unwise forecasts. Odds of that much snow are currently around 20-30%. Good chance that type of forecast would blow all credibility and trust.

FYI...was wrong about CLT looks like 3-5" snow with rest sleet.

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Good deal! Delta, you, and I!

 To clarify what I said. IF ATL is mainly IP, then I'm guessing it gets down to ~25 at the coldest vs. the 12Z Euro's 32. However, if it is mainly ZR, then I'd go more with ~27-28 for the coldest as of now...so say ~5 too warm if mainly ZR.

 

Edit:

 

Folks,

If 31ish for coldest in ZR, can still be VERY bad!!! Think 1973! Ask Tony.

Maybe we can take bets on how cold/warm it will be compared to what actually happens lol

 

No doubt 31 would be cold enough to cause serious problems on power lines, trees, etc. . The depth of the cold air and how thin and cool the mid level warm layer is on other models sounding would mean the drops themselves will be very cold by the time they hit the surface. It makes a big difference if those rain drops fall through a real deep and warm mid level layer and a very shallow subfreezing layer at the surface. That's why sometimes you have a lot of accumulation at 31 and other times you don't. Precip rates also make a difference. You have more freezing if it's a steady and not too precipitation rate. So there are quite a few factors to consider in determining how much actually freezes on objects instead of running off on the ground. 

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OK looks like the euro goes neg with the trough a little later compared to the Canadian which explains the orientation of the precip shield. Small details to iron out but could really affect totals NC on north.

yeah and a little later than last night. Would like to see it go negative earlier.
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Maybe we can take bets on how cold/warm it will be compared to what actually happens lol

 

No doubt 31 would be cold enough to cause serious problems on power lines, trees, etc. . The depth of the cold air and how thin and cool the mid level warm layer is on other models sounding would mean the drops themselves will be very cold by the time they hit the surface. It makes a big difference if those rain drops fall through a real deep and warm mid level layer and a very shallow subfreezing layer at the surface. That's why sometimes you have a lot of accumulation at 31 and other times you don't. Precip rates also make a difference. You have more freezing if it's a steady and not too precipitation rate. So there are quite a few factors to consider in determining how much actually freezes on objects instead of running off on the ground. 

 

 

The trend of the first wave maybe being lighter I think helps anyone in your region who wants more frozen precip, especially ATL/MCN, you don't really want to saturate the atmosphere at 10pm tomorrow night with rain when its a 42/30 spread and then be at 37-39 and have a hard time advecting the wedged dry air in...best case is probably the first wave to be little or nothing or at least hold off til after 06-12Z which would allow for evaporative cooling when the atmosphere is in a better state.

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CAE just put this out for its CWA:

 

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE COLUMBIA SC
242 PM EST SUN FEB 9 2014

...

LINCOLN-MCDUFFIE-COLUMBIA-RICHMOND-BURKE-LANCASTER-CHESTERFIELD-
MCCORMICK-NEWBERRY-FAIRFIELD-KERSHAW-EDGEFIELD-SALUDA-LEXINGTON-
RICHLAND-LEE-AIKEN-SUMTER-BARNWELL-ORANGEBURG-CALHOUN-CLARENDON-
BAMBERG-
...
242 PM EST SUN FEB 9 2014

...INCREASING CHANCE OF WINTRY PRECIPITATION ACROSS MUCH OF THE
MIDLANDS AND CSRA FROM TUESDAY MORNING THROUGH WEDNESDAY NIGHT...

TWO SEPARATE SYSTEMS WILL AFFECT THE REGION FROM TUESDAY MORNING
THROUGH WEDNESDAY NIGHT...WITH BOTH HAVING THE POTENTIAL TO BRING A
WINTRY MIX TO MUCH OF THE AREA. THE BEST CHANCE FOR ACCUMULATING
SNOW WITH BOTH SYSTEMS APPEARS TO BE ACROSS THE NORTHERN MIDLANDS.
AREAS ACROSS THE CENTRAL AND SOUTHERN MIDLANDS...ALONG WITH THE
NORTHERN CSRA...WILL HAVE A GREATER POTENTIAL FOR A MIXTURE OF
FROZEN PRECIPITATION...RANGING FROM SLEET...FREEZING RAIN...AND
ICE PELLETS. THAT REGION WILL HAVE A GREATER POTENTIAL FOR SEEING
FROZEN PRECIP FROM TUESDAY NIGHT INTO WEDNESDAY.

AT THIS TIME THERE IS STILL SOME UNCERTAINTY REGARDING THESE
SYSTEMS. THIS UNCERTAINTY INCLUDES THE TRACK OF THESE LOWS...THE
SURFACE TEMPERATURES THROUGH THESE EVENTS...AND EVEN WITH WHAT
TYPE OF PRECIPITATION WILL EVENTUALLY FALL. WINTER STORM WATCHES
AND WARNINGS WILL MORE THAN LIKELY BE NEEDED WITH LATER FORECASTS.

THE FORECAST WILL CONTINUE TO BE FINE TUNED AS WE GET CLOSER TO
THESE EVENTS.

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**FFC has adjusted the WSWatch**

 

Increased time frame and added new counties.

247 PM EST SUN FEB 9 2014...WINTER STORM WATCH NOW IN EFFECT FROM MONDAY EVENING THROUGHWEDNESDAY MORNING...* LOCATIONS...PORTIONS OF NORTH GEORGIA...MAINLY ALONG AND NORTH  OF A LINE FROM CARROLLTON TO ATLANTA TO HOMER.* HAZARD TYPES...A MIX OF RAIN...SLEET AND SNOW MONDAY  NIGHT...CHANGING BACK TO RAIN TUESDAY AFTERNOON...THEN A MIX OF  FREEZING RAIN AND SLEET TUESDAY NIGHT WITH SNOW IN THE MOUNTAINS.* ACCUMULATIONS...1 TO 2 INCHES OF SNOW WITH 2 TO 4 ACROSS THE  NORTH GEORGIA MOUNTAINS. ICE ACCUMULATIONS WILL BEGIN LATE  TUESDAY NIGHT WITH AMOUNTS OF LESS THAN A TENTH OF AN INCH POSSIBLE.* TIMING...THE RAIN AND SNOW MIX WILL BEGIN ACROSS NORTH GEORGIA  MONDAY EVENING...AND THEN SPREAD INTO THE REST OF NORTH GEORGIA  AFTER MIDNIGHT MONDAY NIGHT. THE PRECIPITATION WILL CHANGE BACK  TO RAIN TUESDAY AFTERNOON...THEN SWITCH TO FREEZING RAIN AND  SLEET TUESDAY NIGHT WITH SNOW ACROSS THE MOUNTAINS. HOWEVER THIS  THREAT MAY NEED TO BE EXTENDED INTO THE WEDNESDAY DAY PERIOD  WITH ADDITIONAL ICE ACCUMULATIONS POSSIBLE.* IMPACTS...SNOW WILL ACCUMULATE ON ROADS MAKING FOR HAZARDOUS  DRIVING CONDITIONS MONDAY NIGHT AND EARLY TUESDAY. ICE WILL  BEGIN TO ACCUMULATE ON ROADS TUESDAY NIGHT AGAIN MAKING FOR  HAZARDOUS DRIVING CONDITIONS. ICING WILL ALSO ACCUMULATE ON TREES  AND POWER LINES WHICH COULD BRING DOWN TREE LIMBS AND POSSIBLY  SOME POWER LINES CAUSING POWER OUTAGES.* TEMPERATURES...FALLING INTO THE LOW TO MID 30S MONDAY  NIGHT...REMAINING IN THE 30S TUESDAY...THEN FALLING INTO THE  UPPER 20S AND LOWER 30S TUESDAY NIGHT.* UNCERTAINTY...THERE IS STILL CONSIDERABLE UNCERTAINTY IN THIS  FORECAST AND SNOWFALL AMOUNTS ARE EXPECTED TO CHANGE LEADING UP  TO THE EVENT. FOLKS ACROSS NORTH GEORGIA SHOULD MONITOR THIS  SITUATION CLOSELY IN THE EVENT THAT THIS WATCH IS UPGRADED TO AN  ADVISORY OR WARNING..
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Different wording on the WSWatch for Central GA:

247 PM EST SUN FEB 9 2014...WINTER STORM WATCH IN EFFECT FROM TUESDAY EVENING THROUGHWEDNESDAY MORNING...THE NATIONAL WEATHER SERVICE IN PEACHTREE CITY HAS ISSUED AWINTER STORM WATCH...WHICH IS IN EFFECT FROM TUESDAY EVENINGTHROUGH WEDNESDAY MORNING.* LOCATIONS...NORTH AND MUCH OF CENTRAL GEORGIA...ALONG AND NORTH  OF A LINE FROM HAMILTON...TO WARNER ROBINS...TO LOUISVILLE.* HAZARD TYPES...A MIX OF FREEZING RAIN AND SLEET WITH FREEZING  RAIN BEING THE PREDOMINANT PRECIPITATION TYPE.* ACCUMULATIONS...ICING AMOUNTS GENERALLY A TENTH OF AN INCH OR  LESS.* TIMING...BEGINNING TUESDAY EVENING ACROSS NORTH GEORGIA AND THEN  SPREADING INTO CENTRAL GEORGIA AFTER MIDNIGHT TUESDAY NIGHT.  HOWEVER THIS THREAT MAY NEED TO BE EXTENDED INTO THE WEDNESDAY  DAY PERIOD WITH ADDITIONAL ICE ACCUMULATIONS POSSIBLE.* IMPACTS...ICING ACCUMULATE ON ROADS MAKING TRAVEL HAZARDOUS.  ICING WILL ALSO ACCUMULATE ON TREES AND POWER LINES WHICH COULD  BRING DOWN TREE LIMBS AND POSSIBLY SOME POWER LINES CAUSING  POWER OUTAGES.* WINDS...NORTHEAST 5 TO 10 MPH WITH GUSTS UP TO 20 MPH.* TEMPERATURES...FALLING INTO THE LOWER 30S.* UNCERTAINTY...THERE IS STILL CONSIDERABLE UNCERTAINTY IN THIS  FORECAST AND SNOW AND ICE AMOUNTS ARE EXPECTED TO CHANGE LEADING  UP TO THE EVENT. FOLKS ACROSS NORTH AND CENTRAL GEORGIA SHOULD  MONITOR THIS SITUATION CLOSELY IN THE EVENT THAT THIS WATCH IS  UPGRADED TO AN ADVISORY OR WARNING.
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Looking like 2/1979 and 1/1988 to me as of right now! If mainly IP, Guessing ~3-4" of IP accumulation and more total accum. if there is sig. snow.

 

Euro 2 meter temp.'s ~5 too warm imo!

If this verifies then it's a major fun time for all under the sleet kapow.  Those two dates, plus my fav in 59 or early 60's, are the best storms for fun ever.  Ever!!!  I've been waiting on this to occur again for a long, long time.  I'm still not letting myself go all in, but I will if it's still there tomorrow.  Been disappointed too many times by a big sleet that never became real, lol.  No amount of snow trumps 4 inches of sleet.  That is just sledding heaven, if it gets cold after.  T

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