1/28 - 1/30 Storm Thread II

[Stormsfury]

The SAV-CHS corridor, especially inland a bit, may be getting hit pretty hard with ~0.75" of qpf, which looks to me to be mainly ZR to start with 850's near +4 C, followed by a change to IP, and then snow toward the end. The two meter 32 line is actually modeled to be very nearby but the Euro sometimes has a warm bias in wintry precip. situations. We'll see. This is similar to the prior run. If any location were to receive over 1/2" of ZR, it could be pretty damaging being that the last one of that caliber or worse was quite a long time back, especially areas south of CHS. SAV hasn't had 0.50" of ZR in many decades.

two key notes here.  EURO +4 at 850mb, cooler than the 0z GFS.  EURO warm bias, if at play would be a tad colder at 850mb, GFS stronger WAA (hence, increased precip) but I think there's going to be a lot of diabatic cooling in the column, and I think that's being missed somewhat, and I think that's reflecting in several WFO forecats, including KCHS.   

[GaWx]

Larry, I was talking to my mother about past snows like this, and she mentioned in 38 or 39 when she was at Wesleyan, they had a big snow where they took trays out of the cafeteria and went sliding.  So that's a Macon snow she remembers, if you've heard of it.  T

 

 I haven't yet found anything in 1938-9, but Macon apparently got a very nice muti-inch dumping 1/23/1940 from 0.54" of liquid. I'm not sure if it all fell as snow without melting some. But they could have gotten close to 5-6" I suppose. Could that be it?

 

Edit: ATL had a very big dump from that one (8-10"), one of the heaviest ever.

[GaWx]

It sounds like the Euro is drier overall.

 

 No, it is similar to the prior run on the coast and a little wetter further inland. It definitely is quite wet near the coast. The furthest NW the 0.05" qpf line goes is now to Atlanta. ATL had nothing on the 12Z run.

[GaWx]

two key notes here.  EURO +4 at 850mb, cooler than the 0z GFS.  EURO warm bias, if at play would be a tad colder at 850mb, GFS stronger WAA (hence, increased precip) but I think there's going to be a lot of diabatic cooling in the column, and I think that's being missed somewhat, and I think that's reflecting in several WFO forecats, including KCHS.   

 

SF,

 I notice that the overall model consensus has 850's in the +3 to +6 range for SAV-CHS for much of the precip. and that the 850's had warmed gradually with the overall NW trend, leading me to worry about a damaging ZR. Are you thinking that the 850's may actually be close to 0C due to underestimating diabatic cooling? Is it realistic that all of the models are missing this? Would that have appreciable effect on 850's or is that more an effect on the surface? Based on my study of old wx maps, if the 850's were to verify, say in the +1 to +3 range instead of +3 to +6, there could very well be much more IP than ZR before the potential change to snow.

[dsaur]

 I haven't yet found anything in 1938-9, but Macon apparently got a very nice muti-iinch dumping 1/23/1940. Could that be it?

 

Edit: ATL had a very big dump from that one (8-10"), one of the heaviest ever.

I'll check with her.  But probably.  I've got photo's of snow up the driveway of the home I grew up in with snow up a couple feet in drifts from that time frame.  And grandmother always talked about a snow in that time frame where it was up the the bottom step on the trolley   They built that house in midtown in 20.  And the photo of the biggest snow was the one of the drive.  I'd put 2 and 2 together and say they were one and the same.  But can't be sure.

  You know, I can't shake the idea of all snow down here.  I don't remember any major snow down here, not in spring, that didn't have a good sleet component.  I can't help but think if this is growing in coverage, the furnace is getting closer too.  Yet that main stripe stays south, though Delta, and Candyman speak of ice mixing in now.  Be interesting to see where the furnace goes.   Tony

[GaWx]

I'll check with her.  But probably.  I've got photo's of snow up the driveway of the home I grew up in with snow up a couple feet in drifts from that time frame.  And grandmother always talked about a snow in that time frame where it was up the the bottom step on the trolley   They built that house in midtown in 20.  And the photo of the biggest snow was the one of the drive.  I'd put 2 and 2 together and say they were one and the same.  But can't be sure.

  You know, I can't shake the idea of all snow down here.  I don't remember any major snow down here, not in spring, that didn't have a good sleet component.  I can't help but think if this is growing in coverage, the furnace is getting closer too.  Yet that main stripe stays south, though Delta, and Candyman speak of ice mixing in now.  Be interesting to see where the furnace goes.   Tony

 

 Ask her if she recalls it being extremely cold for a week or so afterward. Jan. of 1940 is the coldest month on record for ATL, even a little colder than 1/1977!

 

 By the way, keeping in mind climo when SAV does NOT get mainly snow and instead gets more ZR/IP,  analogs suggest that ATL wouldn't be dry and, to the contrary, would actually have a pretty good chance for 1-4". It is when SAV gets mainly snow that ATL is in deep doodoo regarding getting measurable snow such as on 2/9-101973, 1/18/1977, and 12/22-3/1989. We'll see.

[superjames1992]

The 03z SREF is a touch east of the 21z run.

[Stormsfury]

SF,

 I notice that the overall model consensus has 850's in the +3 to +6 range for SAV-CHS for much of the precip. and that the 850's had warmed gradually with the overall NW trend, leading me to worry about a damaging ZR. Are you thinking that the 850's may actually be close to 0C due to underestimating diabatic cooling? Is it realistic that all of the models are missing this? Would that have appreciable effect on 850's or is that more an effect on the surface? Based on my study of old wx maps, if the 850's were to verify, say in the +1 to +3 range instead of +3 to +6, there could very well be much more IP than ZR before the potential change to snow.

Not exactly applying the bias card here, but the fact that the arctic air mass is fresh and building in (and continuing to build in during the entire duration of the event leads me to believe we'll see cooling of the column.  This isn't a case of a damming high pressure to the north of the region, the parent arctic high is still well west of the region (climatologically favored for snow vs ice), although it's clear there will be ZR/IP with this one with the arctic airmass building in with precip coming in.  

[Martin]

Very nice!

[jacobr57]

The new SREF looks good. Continues to give precip further inland than others: .10 - .25 inches of qpf all the way to the NC/TN border. Over an inch for most of the coast and a half inch or more for the triad.

[GaWx]

Not exactly applying the bias card here, but the fact that the arctic air mass is fresh and building in (and continuing to build in during the entire duration of the event leads me to believe we'll see cooling of the column.  This isn't a case of a damming high pressure to the north of the region, the parent arctic high is still well west of the region (climatologically favored for snow vs ice), although it's clear there will be ZR/IP with this one with the arctic airmass building in with precip coming in.  

 

SF,

 Hmm, excellent point! For the six largest IP and/or ZR's at SAV since ~1900 (of which I'm aware; many of these . if not all, also produced the same at CHS), old wx maps show NE US high pressure present, unlike in the current case, in all six cases just in advance of the system producing the ZR/IP and nearly all, if not all, exhibiting damming. So, none of them had a high to the NW building in. (Some of them involved a Miller A in addition.)

[GaWx]

0Z Euro ens.: similar to the 12Z version but actually a little wetter for the coast with a generous 0.75". Also, the trailing wave is shown developing more in the NE Gulf vs. the 12Z but it stays out to sea barely.

[ALhurricane]

0Z Euro ens.: similar to the 12Z version but actually a little wetter for the coast with a generous 0.75". Also, the trailing wave is shown developing more in the NE Gulf vs. the 12Z but it stays out to sea barely.

How much QPF for coastal AL/NW FL?

[GaWx]

How much QPF for coastal AL/NW FL?

 

0.25" AL to 0.50" Apalachicola. A little wetter than the prior run.

[ALhurricane]

0.25" AL to 0.50" Apalachicola. A little wetter than the prior run.

Thanks. Euro continues to be the driest solution for this area. Would like to see it come closer to the other guidance.

[nchighcountrywx]

Significant Shift East Overnight

Quick check on things before heading down to work this morning:

3zSREF Shifts East  (9zSREF not yet available)

6zNAM goes way East with heavy 8+ snow on SENC Coast, 2 to 5 along I-95, Less than inch CLT area.

GSP goes with no Winter Storm Watches. ILM office goes with Winter Storm Warnings. RDU goes with Winter Storm Watch South and East of Raleigh. CAE continues Winter Storm Watch for Central SC and Midlands. CHS continues Winter Storm Watches.

NWS GSP is much better than me explaining why they feel the consensus of the earlier model runs was way overdone and they have not elected to go with any watches for their far Eastern KGSP zones.

Still they note considerable uncertainty exists and local output from GSP, CAE, RDU, ILM and MHX should be monitored closely the next 24 hours.

The following is the KGSP discussion only:

KGSP 335am Area Forecast Discussion

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 330 AM MONDAY...THE MAIN CONCERN WITH THE FORECAST IS THE
POTENTIAL FOR A WINTER STORM TO AFFECT THE CAROLINAS ON TUESDAY AND
WEDNESDAY. THERE REMAINS A GREAT DEAL OF UNCERTAINTY IN THE
FORECAST...MAINLY WITH REGARD TO THE AMOUNT OF PRECIP. THIS APPEARS
TO BE ONE OF THOSE RARE EVENTS FOR THE WESTERN CAROLINAS WHERE THE
PRECIPITATION TYPE IS NOT IN QUESTION. BASED ON THE VERY COLD
PROFILES AND PARTIAL THICKNESSES...IF ANYTHING FALLS OUT OF THE SKY
IT WILL ALMOST CERTAINLY BE IN THE FORM OF SNOW. THE QUESTION IS HOW
MUCH. THE CONCERN WITH THE OPERATIONAL MODELS CONTINUES TO REVOLVE
AROUND THE INTERACTION BETWEEN A NORTHERN STREAM SHORT WAVE AND A
CLOSED LOW OVER NRN MEXICO. THE CONSENSUS IS THAT THE OPERATIONAL
NAM/GFS ARE OVERDONE BECAUSE THEY INCORPORATE THE OLD CLOSED LOW AND
MOISTURE FROM NRN MEXICO AND SPREAD IT EASTWARD ALLOWING FOR MORE
PRECIP TO FALL INTO THE COLD AIR ON THE NORTH SIDE OF A FRONT WHICH
GETS STRUNG OUT OFF THE ATLANTIC SEABOARD. YET...THE MORE PREFERRED
ECMWF SHOWS A DEFINITE TREND OVER THE LAST TWO RUNS TO SPREAD THE
SWATH OF PRECIP FARTHER TO THE NW INTO THE WESTERN CAROLINAS. WHILE
COMPELLING...THE PROBLEM WITH THE 00Z ECMWF IS THAT LIQUID
EQUIVALENT REMAINS INSUFFICIENT TO CREATE ENOUGH SNOWFALL TO WARRANT
AN ADVISORY...MUCH LESS A WATCH AT THIS POINT. MEANWHILE...THE 03Z
SREF CONTINUES TO SUGGEST THAT WARNING CRITERIA SNOWFALL IS
ATTAINABLE OVER THE SOUTHEAST ZONES. THE UNCERTAINTY PROBLEM HAS
BEEN HIGHLIGHTED IN THE MODEL RUN TOTAL SNOW ALL ALONG...WITH
BASICALLY A 50 MILE WIDE SWATH OF ACCUMULATING SNOW SOMEWHERE ACROSS
GEORGIA AND THE CAROLINAS WHICH CHANGES POSITION WITH EACH RUN. THIS
IS REALLY DIFFICULT TO PIN DOWN EVEN 48 HOURS IN ADVANCE. WHAT IS
LIKELY TO HAPPEN IS A VERY SHARP GRADIENT BETWEEN WHO GETS
SIGNIFICANT SNOW...WHO GETS A DUSTING...AND WHO GETS NOTHING AT ALL.
THIS WILL PROBABLY HAPPEN FROM THE SOUTH END TO THE NORTH END OF A
SINGLE COUNTY. AS IT STANDS RIGHT NOW...CONFIDENCE IS NOT HIGH
ENOUGH TO ISSUE A WATCH IN SPITE OF WHAT THE OPERATIONAL GFS AND
SREF MEAN WOULD INDICATE...SO LONG AS AMOUNTS IN THE ECMWF AND
OPERATIONAL NAM REMAIN PALTRY. THERE IS STILL TIME TO ISSUE A WATCH
AS THE IMPACT WOULD BE MAINLY IN THE TUESDAY NIGHT PERIOD. IN THE
BEST SCENARIO...LIGHT PRECIP WOULD DEVELOP OVER THE AREA LATE
TUESDAY AFTERNOON. FOR THE TIME BEING...THE PRECIP CHANCES S OF I-85
WERE KEPT IN THE CHANCE RANGE IN AN EFFORT TO MANAGE EXPECTATIONS...
IN THAT A LIKELY OR CATEGORICAL POP SHOULD NOT BE TAKEN AS AN
INDICATION THAT SIGNIFICANT SNOW IS EXPECTED. THIS IS LIKELY TO
CHANGE LATER TODAY AND A WATCH MIGHT STILL BE ISSUED. STAY TUNED.

THE REST OF THE SHORT RANGE PERIOD LOOKS RELATIVELY BENIGN. AFTER
PRECIP PULLS OUT WEDNESDAY MORNING...CLEARING WILL WORK IN FROM THE
WEST AND TEMPS WILL REMAIN WELL BELOW NORMAL. THE UPPER TROF AXIS
SHOULD SWING THROUGH WEDNESDAY NIGHT...BUT NO PRECIP IS EXPECTED
BECAUSE OF DEEP LAYER DRYING. YET ANOTHER ARCTIC HIGH WILL SETTLE
OVER THE REGION BY THURSDAY MORNING.

 

Updated with Monday 4:55am KGSP Forecast Area Snow Total Accumulation Graphic

 

[BullCityWx]

That is complete BS. There has not been a significant shift east on the SREF. As usual, you're lying. The mean on the 3Z SREF plumes is maybe half an inch less for CLT. How is that significant?

[BullCityWx]

AN ADVISORY...MUCH LESS A WATCH AT THIS POINT. MEANWHILE...THE 03Z

SREF CONTINUES TO SUGGEST THAT WARNING CRITERIA SNOWFALL IS

ATTAINABLE OVER THE SOUTHEAST ZONES. THE UNCERTAINTY PROBLEM HAS

For Christs sake, THEY SAY IT IN THE DISCUSSION.

[mikepie]

Looks like FFC is adding core metro counties to the WSW. The last paragraph will no doubt give the grocery stores a nutty day...

...WINTER STORM WATCH IN EFFECT FROM TUESDAY MORNING THROUGH

WEDNESDAY AFTERNOON...

THE NATIONAL WEATHER SERVICE IN PEACHTREE CITY HAS ISSUED A

WINTER STORM WATCH...WHICH IS IN EFFECT FROM TUESDAY MORNING

THROUGH WEDNESDAY AFTERNOON.

* LOCATIONS...ALONG AND SOUTH OF A LINE FROM HARALSON TO NORTH FULTON

TO MADISON COUNTY.

* HAZARD TYPES...SNOW.

* ACCUMULATIONS...1/2 INCH TO 2 INCHES.

* TIMING...SNOW IS EXPECTED TO BEGIN AS EARLY AS MID MORNING

TUESDAY AND LAST INTO TUESDAY NIGHT.

* IMPACTS...SNOW COVERED ROADS COULD MAKE TRAVEL DIFFICULT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WATCH MEANS THERE IS A POTENTIAL FOR SIGNIFICANT

SNOW...SLEET...OR ICE ACCUMULATIONS THAT MAY IMPACT TRAVEL.

CONTINUE TO MONITOR THE LATEST FORECASTS.

NOW IS THE TIME TO PREPARE FOR THIS WINTER STORM. BE SURE TO BUY

NON PERISHABLE FOODS. MAKE CONTINGENCY PLANS IF YOU PLAN ON

TRAVELING DURING THIS PERIOD. IF YOU CAN CHANGE YOUR TRAVEL...DO

SO BEFORE THE EVENT STARTS. NOW IS THE TIME TO PLAN...DO NOT WAIT

FOR THE WARNING!

&&

$$

[packfan98]

6z gfs went way east. Confines the best precip east of I-95.

[WXinCanton]

Trough not as sharp on the 6z GFS.  Not as much interaction with the energy over MX. Really backed down on the QPF for all of GA.  

[WXinCanton]

Very good discussion by FFC:

 

BIG PICTURE...CONFIDENCE IS INCREASING THAT AT LEAST A PORTION OF
THE FORECAST AREA WILL SEE SIGNIFICANT IMPACTS FROM THIS WINTER
STORM. INGREDIENTS SEEM TO BE COMING TOGETHER IN THE FORM OF A
PHASING OF THE NORTHERN AND SOUTHERN STREAM JETS ALONG WITH
PRECIPITATION DEVELOPING WITHIN THE COLD SECTOR AS A WEAK LOW
FORMS AT THE SURFACE OFF THE SOUTHEAST GEORGIA COAST. THE DEVIL OF
COURSE IS ALWAYS IN THE DETAILS.

UNCERTAINTIES...MODELS ARE NO CLOSER WITH THE LATEST RUN IN HONING
IN ON A SOLUTION WITH THE EURO AND UKMET IN ONE CAMP WHILE THE
GFS...NAM12 AND SREF REMAIN IN ANOTHER AND THERE EVEN SIGNIFICANT
VARIATIONS WITHIN EACH CAMP AS WELL. EURO DID TREND SLIGHTLY
TOWARD THE GFS AND NAM12 WHICH GIVES CAUSE FOR CONCERN THAT NORTH
GEORGIA WOULD BE MORE SIGNIFICANTLY IMPACTED BUT WPC REMAINS
COMMITTED TO THE DRIER 12Z SUITES WITH MOST ACCUMULATION ACROSS OUR
SOUTHERN TIER. HARD TO ARGUE EITHER WAY WITH THIS SYSTEM BUT BASED
ON SUBJECTIVE ANALYSIS SO FAR THIS WINTER...WOULD PERSONALLY FAVOR
PRECIP SPREADING FURTHER NORTH THAN MODELS PROJECT WHICH WOULD IN
THIS CASE BRING WINTER HAZARDS NORTHWARD AS WELL. SO BASED ON
THAT...HERE IS WHAT WE ARE GOING WITH.

SNOW/SLEET/FREEZING RAIN...NOW HAVE LIKELY TO CATEGORICAL SNOW
ACROSS ENTIRE ATLANTA METRO AND EXTEND FROM HARALSON COUNTY TO
MADISON. MOST SIGNIFICANT ACCUMULATIONS WOULD BE JUST SOUTH OF THE
METRO WITH 2 TO 4 INCHES FROM GREENVILLE TO MILLEDGEVILLE. TO THE
SOUTH OF THIS...ACCUMULATIONS WILL BE LIMITED BY A MIX OF SLEET
AND FREEZING RAIN BUT IMPACTS MAY BE GREATER GIVEN THE ICE
POTENTIAL. FOR EXTREME SOUTHEAST TIER...RAIN MAY BE MORE PREVALENT
THAN FIRST THOUGHT BUT STILL A WINDOW FOR SIGNIFICANT ICING FROM
DOOLY THROUGH TOOMBS COUNTIES.

WHERE FORECAST COULD GO WRONG...THERE ARE VERY FEW ANALOGS FOR
THIS SYSTEM WHICH MATCH UP WELL MEANING THIS IS NOT A PATTERN WE
TYPICALLY SEE. THIS IS ESPECIALLY TRUE WRT THE DRY AIR COMING IN
WHICH IS LOWER THAN IS TYPICAL WITH THIS TYPE OF SYSTEM. POTENTIAL
EXISTS FOR NORTHERN SEGMENT OF PRECIP SHIELD TO PRODUCE MUCH LESS
PRECIP AND HENCE ACCUMULATIONS THAN CURRENTLY FORECAST. FOR THESE
REASONS...HAVE LEFT WATCH IN PLACE FOR NOW WHILE EXPANDING
NORTHWARD AND ROW OF COUNTIES. WILL AWAIT 06Z RUN TO SEE IF
UPGRADE TO WARNING IS JUSTIFIED.

AXIS OF PRECIP ROTATES OUT BY WED MORNING WITH MIX TRANSITIONING
TO ALL SNOW BUT QPF REMAINING LIGHT ENOUGH TO PRECLUDE ADDITIONAL
SIGNIFICANT ACCUMULATIONS.

[Plowable]

I see they have us under a Winter Storm Warning now so imma guessin thats a good thing . Kinna excited at the prospect of a real storm here at the beach.

[NavarreDon]

Not often you see this type (inverted) of snowfall map from GSP!

 

[FallsLake]

The 6z GFS did shift east. Looks like the best precip is going to be south and east of Raleigh, but the .5 liquid line does get to about the RDU airport and the .25 line gets all the way back to near Greensboro/Charlotte and the .1 back past Winston-Salem/S Foothills. Definitely a big drop off but many of us should still feel good about this run. The Euro trended some to the west last night and we should have known that the weenie run (18z) was going to verify lower. As far as I'm concerned GAME ON! 

[packfan98]

When will we know how the northern and southern pieces of energy are going to interact? It looked like the models were converging on a phase scenario, but then overnight and this morning it went back to showing less interaction. Are all of the players on the field now? If so, are they acting the way the models have been showing? At what time will we know how much phasing there is? Thanks to anyone who cares to respond! I think many of us want to know what to be looking for today.

[timnc910]

Mhx didn't even put up a watch they went with th e real deal

DUPLIN:

...WINTER STORM WARNING IN EFFECT FROM 10 AM TUESDAY TO 4 PM EST WEDNESDAY ...

THE NATIONAL WEATHER SERVICE IN NEWPORT/MOREHEAD CITY HAS ISSUED A WINTER STORM WARNING FOR ALL OF EASTERN NORTH CAROLINA ...WHICH IS IN EFFECT FROM 10 AM TUESDAY TO 4 PM EST WEDNESDAY.

* ACCUMULATIONS ...SNOW ACCUMULATION OF 4 TO 8 INCHES WITH LOCALLY HIGHER AMOUNTS. SOME MINOR ICE ACCRETION OR SLEET MAY OCCUR ALONG COASTAL SECTIONS.

* TIMING ...TUESDAY MORNING THROUGH WEDNESDAY. THE HEAVIEST SNOWFALL WILL OCCUR TUESDAY NIGHT.

* IMPACTS ...DRIVING WILL BECOME VERY HAZARDOUS ...ESPECIALLY TUESDAY NIGHT WHEN THE HEAVIEST SNOW IS EXPECTED.

* WINDS ...NORTH 10 TO 15 MPH WITH GUSTS UP TO 25 MPH.

* TEMPERATURES ...REMAINING STEADY IN THE 20S.

* WIND CHILL ...AS LOW AS 8 ABOVE.

PRECAUTIONARY/PREPAREDNESS ACTIONS ...

A WINTER STORM WARNING FOR HEAVY SNOW MEANS SEVERE WINTER WEATHER CONDITIONS ARE EXPECTED OR OCCURRING. SIGNIFICANT AMOUNTS OF SNOW ARE FORECAST THAT WILL MAKE TRAVEL DANGEROUS. ONLY TRAVEL IN AN EMERGENCY. IF YOU MUST TRAVEL ...KEEP AN EXTRA FLASHLIGHT ... FOOD ... AND WATER IN YOUR VEHICLE IN CASE OF AN EMERGENCY. NEVER USE A GENERATOR INDOORS. GAS GRILLS, GENERATORS, AND CAMP STOVES CREATE DEADLY CARBON MONOXIDE FUMES THAT WILL BUILD UP WHEN USED

[packfan98]

OK, here's a quick summary of the past three runs of the GFS ensembles.  The trend is not good folks.  The phase bomb looks to be off the table for now.

 

EPIC 18z GEFS

0z GEFS (still respectable)

 

and now the just released 06z GEFS 

[mackerel_sky]

Not what we wanted to see on the 6z GFS . Any chances on this trending west? Will the short term models be more accurate right now? Do the GEFS follow the east trend? Was pretty bold to have Charlotte getting sunny on the point and click forecast on Wed.!

[NCSNOW]

Yep no doubt the trend is not a good one west of 95 in NC. Pretty telling when NWS throws the NAM and GFS out in the AFD and rides the Euro/UKIE. 12z should pretty much have this nailed down today. I'm right back where I started IMBY trying to get .10-.15 with ratio fighting the virga factor just so we can see the ground covered in something beside frost. Without the phase it's gonna be to hard to rely on just overrunning to get enough qpf back this way. The American models threw to much weight into the NS.