Georgia and the Carolinas ... possible effects for 1/9-1/10.

[Stormsfury]

Basically looks to be a minor event ... but an event nonetheless, with some implications possible due to poor handling of the cold and very dry air in place for this event.

http://www.stormsfury1.com

(My Forecast/Prog Discussions)...

[Stormsfury]

SOUTH CAROLINA STATE WEATHER ROUNDUP
NATIONAL WEATHER SERVICE COLUMBIA SC
100 PM EST WED JAN 07 2004

Note: "fair" indicates few or no clouds below 12,000 feet with no
significant weather and/or obstructions to visibility.

SCZ003-006-007-009-010-071900-
UPSTATE

CITY SKY/WX TMP DP RH WIND PRES REMARKS
ANDERSON MOSUNNY 37 8 30 W8 30.46F WCI 31
6HR MIN TEMP: 17; 6HR MAX TEMP: 38;

GREENVILLE MOSUNNY 33 2 26 VRB3 30.44F
6HR MIN TEMP: 20; 6HR MAX TEMP: 34;

GREENWOOD MOSUNNY 36 8 31 VRB5 30.47F WCI 32
6HR MIN TEMP: 16; 6HR MAX TEMP: 36; 6HR PCP: TRACE;

GREER MOSUNNY 34 3 27 N6 30.43F WCI 29
6HR MIN TEMP: 19; 6HR MAX TEMP: 34;

ROCK HILL MOSUNNY 38 1 21 NW3 30.44F
6HR MIN TEMP: 18; 6HR MAX TEMP: 39; 6HR PCP: TRACE;

$$

SCZ027-028-031-032-036-071900-
CENTRAL

CITY SKY/WX TMP DP RH WIND PRES REMARKS
COLUMBIA APT PTSUNNY 38 2 22 W8 30.48F WCI 32
6HR MIN TEMP: 25; 6HR MAX TEMP: 39;

COLUMBIA OWENS PTSUNNY 39 -1 18 VRB7 30.49F WCI 34
6HR MIN TEMP: 25; 6HR MAX TEMP: 39;

FLORENCE SUNNY 37 2 22 N7 30.47F WCI 32
6HR MIN TEMP: 22; 6HR MAX TEMP: 38;

MCENTIRE ANGB PTSUNNY 39 1 20 W10 30.47F WCI 32
ORANGEBURG PTSUNNY 38 0 20 VRB3 30.49F
6HR MIN TEMP: 24; 6HR MAX TEMP: 39;

SUMTER SHAW PTSUNNY 41 7 24 VRB3 30.46F
$$

SCZ034-044-045-048-050-071900-
COAST

CITY SKY/WX TMP DP RH WIND PRES REMARKS
MYRTLE BEACH MOSUNNY 41 3 20 N9G17 30.47F
N MYRTLE BCH SUNNY 41 5 22 N7 30.44F
6HR MIN TEMP: 27; 6HR MAX TEMP: 41;

CHARLESTON APT MOSUNNY 41 6 23 N9 30.47F
6HR MIN TEMP: 24; 6HR MAX TEMP: 42;

BEAUFORT MOSUNNY 43 6 21 VRB6 30.49F
6HR MIN TEMP: 29; 6HR MAX TEMP: 44;

[GAStorm]

Good discussion SF! Do you think the ATL metro area will see more of a mix than rain out of this? It seems like we usually get sleet at the onset with the low dewpoints. Not sure how long it would last, or if we could see snow mixed in? Any comments would be appreciated!

[FLguy]

great discussion...

i agree overall but in order toget higher QPFs you would need more in the way of WAA (warm advection and isentropic ascent) overrunning the cold dome(this is because the warmer air can hold more moisture)...so there may be a sleet and FRZRA problem in some locations where the WAA brings mid-level temps above freezing however due to the cold air in place evaporational cooling processes would fight it off initially as the atmosphere becomes saturated. but to keep an all snow situation in the face of strong WAA w/o any resistance is hard to acheive along the coastal plain.

also remember CSI and localized higher which may occur where banding sets up in areas coldenough to see all snow through the event.

[Stormsfury]

Good discussion SF! Do you think the ATL metro area will see more of a mix than rain out of this? It seems like we usually get sleet at the onset with the low dewpoints. Not sure how long it would last, or if we could see snow mixed in? Any comments would be appreciated!

I'm pretty sure timing of the system will greatly enhance or reduce the chances of wintry weather in the immediate ATL area, but looking at the DP's and the current temperature of 32º with a 4º DP, temperatures IMHO, would have a tough time recovering with such a weak SFC reflection despite decent isentropic lifting. And yes, sleet at the onset is probably a good bet since evaporational cooling can't effectively dry out IP like rain or snow.

SF

[donsutherland1]

Excellent discussion, SF. While the system might be a "minor event," your new avatar appears to be a major event.

[FLguy]

Excellent discussion, SF. While the system might be a "minor event," your new avatar appears to be a major event.

yep...thats definately a MAJOR hit.

[Stormsfury]

Excellent discussion, SF. While the system might be a "minor event," your new avatar appears to be a major event.

Thanks Don ... on BOTH accounts. My g/f resembles a LOT like Eliza Dushku (from Buffy the Vampire Slayer fame). I wasn't even online last night since Becky and I went out last night.

SF

[Stormsfury]

great discussion...

i agree overall but in order toget higher QPFs you would need more in the way of WAA (warm advection and isentropic ascent) overrunning the cold dome(this is because the warmer air can hold more moisture)...so there may be a sleet and FRZRA problem in some locations where the WAA brings mid-level temps above freezing however due to the cold air in place evaporational cooling processes would fight it off initially as the atmosphere becomes saturated. but to keep an all snow situation in the face of strong WAA w/o any resistance is hard to acheive along the coastal plain.

also remember CSI and localized higher which may occur where banding sets up in areas coldenough to see all snow through the event.

I noticed that the 12z ETA depicted a lot more in the way of ZR through NC on this run compared to the previous runs, and it's quite possible that before the system moves off the SC coast, that a minor icing occurs there. But I won't rule out the possibility as the system exits, residual moisture in wake of weak CAA turns the leftover moisture to snow before ending (although light, and would probably occur with temperatures just above FRZ.)

SF

[donsutherland1]

It sounds like you have a great gf (based on your post here and at WWBB). I'm sure the romance will help keep you warm in this cold period that is now upon the East (did you see it was 25F this morning in Charleston?).

[Stormsfury]

It sounds like you have a great gf (based on your post here and at WWBB). I'm sure the romance will help keep you warm in this cold period that is now upon the East (did you see it was 25F this morning in Charleston?).

Yeah ... I felt every bit of that cold outside after I left Becky's place this morning ... Morning low here was 23º, and currently 44º (CHS) and here ... dewpoint is 7º, with 21% RH's...

SF

[GAStorm]

I'm pretty sure timing of the system will greatly enhance or reduce the chances of wintry weather in the immediate ATL area, but looking at the DP's and the current temperature of 32º with a 4º DP, temperatures IMHO, would have a tough time recovering with such a weak SFC reflection despite decent isentropic lifting. And yes, sleet at the onset is probably a good bet since evaporational cooling can't effectively dry out IP like rain or snow.

SF

You made a good point about the current temp and dewpoint here. We were suppose to be in the low 40's today, and I really don't see that happening being at 32! BTW, the website looks great, and so does that avatar as well!!

[Stormsfury]

Which brings another point on just how the model guidance is handling the arctic air (albeit modified and this with a LACK of snowcover across the Southeast and the Mid-Atlantic as well), as generally being the temperatures and the guidance being roughly 3º-5º too warm vs actual temperatures ... here, it's 44º degrees and CHS called for mid 40's (undercutting the MOS guidance by 3º) so good job on their part.

Soundings from ATL and CHS give an example of the shallow nature of the arctic air and notice the temperatures at the 950mb vs on up to the 700mb in ATL ... (time sensitive)

[GAStorm]

Very interesting indeed SF! Definitely something to keep an eye on when the precip moves in!

[Stormsfury]

CHS's AFD today highlights the same possible expectations for the Coastal Plain of SC on Friday/Friday Night ...

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
300 PM EST WED JAN 7 2004

.PUBLIC...DEWPTS IN THE SINGLE DIGITS ACROSS THE AREA WITH SOME CI
MOVING THROUGH. ADDITIONAL HIGH CLOUDS TO MOVE INTO THE AREA LATER
TONIGHT AND BECOME THICKER. MODELS HAVE BACKED OFF A FEW DEGREES ON
OVERNIGHT LOWS FROM PREV RUNS. ONCE THE SUN GOES DOWN TEMPS SHOULD
DROP RATHER DRAMATICALLY. WINDS WILL BECOME CALM...OR AT LEAST VERY
LIGHT ALONG THE COAST. GIVEN THE LOW TEMPS WE ARE STARTING WITH AND
THE FACT THAT BETTER CLOUD COVER IS STILL A WAYS AWAY...PLAN TO GO
WITH OR SLIGHTLY BELOW LOWEST MOS GUID FOR TONIGHT. EXPECT TO SEE
SOME READINGS IN THE TEENS BY MORNING. INCREASING AND LOWERING
CLOUDS ON THU WITH TEMPS STRUGGLING INTO THE LOWER 50S.

LIGHT PRECIP IS EXPECTED TO START LATE THU NIGHT AFTER ATMOSPHERE
HAS HAD TIME TO WARM A BIT...WHICH SHOULD KEEP PRECIP IN THE LIQUID
FORM. WILL TAKE A PERIOD OF OVERRUNNING TO MOISTEN UP LOWERST LAYERS
FIRST. PREFER MORE OF A GFS SOLN FOR OVERALL FORECAST. BEST CHANCE
OF PRECIP WILL BE IN THE FRI MORNING HOURS BEFORE LOW DEVELOPS AND
TAKES DEEPER MOISTURE AND LIFT TO THE NE. WILL LEAVE A SLIGHT CHANCE
IN FOR FRI EVENING WITH PRECIP CHANCES TO TAPER OFF RAPIDLY FRI
NIGHT AS LOW PRES HEADS NE. THIS IS A GOOD THING AS TEMPS IN LOWEST
LAYERS DROP OFF QUICKLY OVERNIGHT FRI AND ANY PRECIP THAT LINGERED
TOWARDS SAT MORNING WOULD BE FROZEN. COOLER AIR TO FILTER IN FRI
NIGHT AND SAT BEHIND REINFORCING COLD FRONT. MOISTURE BY THIS TIME
WILL BE ONLY VERY SHALLOW SO WEAK SHORTWAVES MOVING THROUGH SHOULD
HAVE LITTLE EFFECT ON SENSIBLE WEATHER...BUT WILL MAINTAIN CLOUD
COVER FOR THAT TIME. UPR TROF TO MOVE OFF THE COAST EARLY ON SAT.

RELATIVELY QUIET THEN FOR SUN WITH NEXT CHANCE OF PRECIP MON AND MON
NIGHT.

[FLguy]

[quote="Stormsfury"]Which brings another point on just how the model guidance is handling the arctic air (albeit modified and this with a LACK of snowcover across the Southeast and the Mid-Atlantic as well), as generally being the temperatures and the guidance being roughly 3º-5º too warm vs actual temperatures ... here, it's 44º degrees and CHS called for mid 40's (undercutting the MOS guidance by 3º) so good job on their part.

Soundings from ATL and CHS give an example of the shallow nature of the arctic air and notice the temperatures at the 950mb vs on up to the 700mb in ATL ... (time sensitive)

http://orbit35i.nesdis.noaa.gov/goes/so ... s/kchs.gif

http://orbit35i.nesdis.noaa.gov/goes/so ... s/katl.gif[quote]

yes and notice the KI (K Index) values at CHS and ATL are very low which further illustrates the presence of VERY dry air in the mid levels. now the K index paramater is most commonly used in severe wx and hvy rainfall forecasting though since it compares the relationship between temps...dewpoints and dewpoint depressions at three manditory pressure levels it can also effectlively be used to make an assessment of how dry the airmass over a specific location is.

in addition...once precipitation does begin to fall across the region ---- evaporative cooling processes will force temperatures to fall to the wetbulbs...therefore bholstering the potential for wintry precipitation across the southeast.

[Stormsfury]

I guess I should add this real time US MAP of the DP's as well ...

[FLguy]

I guess I should add this real time US MAP of the DP's as well ...

the figure below goes hand in hand with the 2m Td map above. the below figure depicts KI values across the CONUS.

http://twister.sbs.ohio-state.edu/severe/kindex.html

notice how the VERY low KI values correspond to the low RH values and dry air across the southeast US.

[Bane]

From MOrehead City:

.SHORT TERM...TONIGHT WILL BE ONE OF THE COLDEST NIGHTS OF THE
SEASON...AS AN ARCTIC HIGH BUILDS OVER THE REGION. CLEAR SKIES AND
FRIGID AIR ACROSS EASTERN NORTH CAROLINA WILL ALLOW TEMPERATURES TO
DROP INTO THE TEENS INLAND...AND TO THE LOWER 20S ALONG THE COAST.
FOR THURSDAY...SUNNY SKIES WILL HAVE LITTLE AFFECT IN WARMING THE
AIR...AS TEMPERATURES STRUGGLE TO CLIMB INTO THE LOWER TO MID 40S.
BY THURSDAY NIGHT...CLOUDS AHEAD OF A WEAK SHORTWAVE WILL BEGIN TO
CREEP INTO THE REGION. THIS SYSTEM WILL PROVIDE ENOUGH LIFT OVER
THE AREA TO PRODUCE A FEW LIGHT FLURRIES IN THE VERY EARLY MORNING
HOURS FRIDAY.

BY 12Z FRIDAY...A STRONGER AND MORE ORGANIZED SYSTEM OFF THE SE COAST
WILL BRING A MORE LIKELY CHANCE OF SNOW. LIFT ASSOCIATED WITH THIS
SFC LOW WILL BE IMPRESSIVE...BUT MODELS CURRENTLY KEEP THE SYSTEM
WELL TO THE S OF THE REGION FOR ANY SIGNIFICANT ACCUMULATION TO
OCCUR. THE ETA PLACES THE SFC LOW SLIGHTLY CLOSER TO THE COAST AS IT
IS QUICKER TO ERODE THE WEAK RIDGE TO THE N. IF THIS SOLUTION
OCCURS...IT IS POSSIBLE THAT UP TO 4-5" OF SNOW COULD FALL ALONG THE
OUTER BANKS AS THE LOW WILL BE SLOWER TO MOVE OFF TO THE EAST. THE
GFS/ECMWF SEEM TO HAVE A SLIGHTLY FASTER SOLUTION AND THEY KEEP THE
SFC LOW MORE OFF SHORE. IN THIS SCENARIO THE MOST IMPRESSIVE LIFT IS
STILL CENTERED AROUND THE OUTER BANKS REGION...BUT QPF WILL BE
AROUND 0.15" (APPROX 1.5" SNOW EQUIVALENT). CONTINUED WITH THE GFS
AS IT SEEMS TO HAVE A BETTER HANDLE SYNOPTIC SYSTEMS AND HAS THE
BETTER CONSISTENCY. BY SAT THE SYSTEM WILL HAVE MOVED MORE TOWARD
THE E...WHICH WILL CREATE SOME 20-25KT N WINDS ALONG THE OUTER
BANKS. THIS COULD FAVOR SOME OCEAN ENHANCED SNOW SHOWERS ALONG THE
OUTER BANKS UNTIL AROUND 18Z UNTIL ALL THE LIFT AND MOISTURE
DIMINISH. OVERALL...A WEAK SHORTWAVE AHEAD OF A MID LEVEL TROUGH
WILL BRING ADEQUATE MOISTURE AND LIFT TO PRODUCE SOME FLURRIES IN
THE AM HOURS ON FRI. THE BEST CHANCE FOR ACCUMULATION WILL OCCUR
AROUND FRI AFTERNOON/FRI NT TIME PERIOD NOTABLY ALONG THE OUTER
BANKS AS SFC LOW PASSES OFF SHORE. ELSEWHERE...AREAS IN THE NW PART
OF THE CWA CAN EXPECT FLURRIES BUT LITTLE IN THE WAY OF
ACCUMULATION. ANOTHER TROUGH IS PROGGED TO MOVE INTO THE REGION
AROUND TUESDAY BRINGING A BETTER CHANCE FOR SOME MEASURABLE RAIN.
TEMPERATURES FOR THE MOST PART WILL REMAIN COOL AND SEASONABLE.

[Bane]

Also from Morehead City:

UNSEASONABLE COLD AIR AND CHANCE FOR LIGHT SNOW THIS WEEK...

AN UNSEASONABLY COLD AIRMASS HAS MOVED INTO THE REGION. TEMPERATURES
TONIGHT ARE EXPECTED TO FALL TO THE UPPER TEENS INLAND...WITH LOWER
20S ALONG THE CENTRAL COAST AND OUTER BANKS...MAKING WEDNESDAY NIGHT
AND EARLY THURSDAY MORNING ONE OF THE COLDEST NIGHTS OF THE SEASON.
RESIDENTS SHOULD TAKE THE USUAL PRECAUTIONS FOR EXTREMELY COLD
OVERNIGHT TEMPERATURES...SUCH AS PROTECTING WATER PIPES...AND
PROVIDING WARMTH FOR OUTDOOR PETS. ONE WAY TO PROTECT EXPOSED
PLUMBING IS BY LETTING YOUR FAUCETS DRIP OVERNIGHT.

IN ADDITION TO THE EXTREME OVERNIGHT COLD TEMPERATURES...A QUICK
MOVING LOW PRESSURE SYSTEM WILL BRING THE CHANCE FOR SOME LIGHT SNOW
ON FRIDAY. GIVEN THE SPEED AND EXPECTED TRACK OF THIS SYSTEM...ONLY
FLURRIES OR LIGHT SNOW IS EXPECTED AT THIS TIME.