1/22-1/22 Winter Storm Threat

[NorthHillsWx]

11 minutes ago, BornAgain13 said:

18z EPS corrected back north and west for us folks more inland...

That’s beautiful. Literally the entire forum gets accumulating snow. Maybe we’ll trend that way 

[franklin NCwx]

1 hour ago, Brick Tamland said:

RAH did say for now it could be a low to moderate impact event here. Would be nice if the models didn't show such good storms for your location 7 days out only to turn into a mess. I would still like getting 1 to 2 inches of snow. But it looks like the Euro run overnight might have been a head fake and got everyone excited because the Euro was finally on board. But ever since then it and the other global models have been decreasing the totals. Canadian still has a nice storm, but it is also less with the totals. The NAM is the only hope now unless the others start changing tomorrow.

Lol...right on queue!

[Prismshine Productions]

11 minutes ago, BornAgain13 said:

18z CMC looks similar to the 12z. Doesn't look further south... Looks like it held serve...

low in the gulf is NW

[VABILLUPS1]

[GaWx]

From NWS CHS: surrealistic!

MONDAY NIGHT INTO TUESDAY, THE HIGHLY AMPLIFIED UPPER TROUGH   
TRENDS TOWARD A POSITIVE TILT WHILE SEVERAL SOUTHERN STREAM   
SHORTWAVES DEVELOP. LATE MONDAY NIGHT, A WEAK COASTAL TROUGH IS  
FORECAST TO DEVELOP JUST OFF THE GA COAST. ALTHOUGH THE BRUNT OF  
THE MOISTURE AND FORCING ARE EXPECTED TO REMAIN OFFSHORE, WEAK  
MOIST ISENTROPIC ASCENT COULD PRODUCE SOME LIGHT PRECIP ALONG  
THE GA COAST LATE MONDAY NIGHT. OUR HOURLY TEMPERATURE VALUES  
DURING THIS TIME WOULD BE RIGHT AROUND FREEZING, SO IF ANY  
PRECIPITATION DOES DEVELOP, IT COULD FALL AS LIGHT FREEZING  
RAIN.  
  
DURING THE DAY TUESDAY, A STRONG DIGGING SHORTWAVE WILL TRAVERSE  
THE SOUTH CENTRAL UNITED STATES. EXTENSIVE CLOUD COVER AND COLD  
AIR ADVECTION WILL YIELD A CHILLY DAY WITH HIGHS ONLY IN THE  
MID/UPPER 30S IN SOUTHERN SC AND LOW/MID 40S IN SOUTHEAST GA.   
MOISTURE WILL SLOWLY OVERSPREAD THE AREA FROM THE SOUTHWEST LATE  
TUESDAY, AND EVENTUALLY SOME FORCING FOR ASCENT WILL TRANSPIRE.  
HOWEVER, MOST GUIDANCE HAS TRENDED A BIT DRIER ON TUESDAY WITH   
LITTLE TO NO PRECIPITATION THROUGH SUNSET. WE HAVE NOT FULLY   
JUMPED ON THIS POSSIBILITY GIVEN THAT MODELS ARE NOTORIOUS FOR   
STARTING PRECIPITATION TOO LATE IN THESE SCENARIOS, SO WE  
MAINTAINED CHANCE POP TUESDAY AFTERNOON. AS FAR AS   
PRECIPITATION TYPE, MODEL SOUNDINGS SUPPORT SNOW ACROSS THE   
INLAND HALF OF OUR AREA, THEN THINGS GET TRICKY AS ONE MOVES   
CLOSER TO THE COAST. A DECENT WARM LAYER IN THE LOWEST COUPLE   
THOUSAND FEET, COMBINED WITH FAIRLY DRY AIR WITHIN THE DENDRITIC  
GROWTH ZONE, INDICATES THE POTENTIAL FOR RAIN OR SNOW IN THE   
REST OF THE FORECAST AREA. ALONG THE GA COAST THE ATMOSPHERE   
LOOKS TOO WARM TO SUPPORT ANYTHING OTHER THAN RAIN. THIS IS ALL  
CONTINGENT ON ANY PRECIPITATION EVEN OCCURRING, WHICH STILL   
LOOKS IFFY FOR TUESDAY AFTERNOON. AT THIS POINT, GIVEN THE LOW   
CONFIDENCE IN ANY QPF, WE DO NOT SHOW ANY SNOW OR ICE   
ACCUMULATIONS FOR TUESDAY AFTERNOON.  
  

  
   
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/  
  
THE FORECAST IS QUITE INTERESTING IN THE LONG TERM PERIOD,  
ALBEIT EXTREMELY CHALLENGING. THE PRIMARY UPPER SHORTWAVE WILL  
PASS THROUGH THE SOUTHEAST TUESDAY NIGHT AND WEDNESDAY.  
MEANWHILE THE ARCTIC HIGH PRESSURE WILL REMAIN ANCHORED OVER THE  
CENTRAL APPALACHIANS, MAINTAINING A COLD NORTHERLY FLOW IN  
LOW/MID LEVELS. DEEP SYNOPTIC FORCING ASSOCIATED WITH THE  
SHORTWAVE WILL SPUR WIDESPREAD PRECIPITATION TUESDAY NIGHT INTO  
WEDNESDAY MORNING. MODELS ARE ACTUALLY IN REASONABLY GOOD  
AGREEMENT ON THE TOTAL LIQUID PRECIPITATION RANGING FROM  
0.25-0.50" FAR INLAND AND 0.5-0.75" ELSEWHERE. HOWEVER,  
DETERMINING THE SNOWAMT AND ICEACCUM IS MUCH MORE CHALLENGING  
BECAUSE IT DEPENDS ON P-TYPES.   
  
MODEL SOUNDINGS INDICATE A LACK OF ICE NUCLEI ACTIVATION AT THE  
ONSET OF THE MAIN FORCING TUESDAY EVENING. HOWEVER, THERE SHOULD  
BE AMPLE COLD, DRY AIR IN THE LOW-LEVELS SUCH THAT TEMPS WILL  
QUICKLY COOL TO FREEZING AT THE SURFACE. THIS COULD YIELD  
FREEZING RAIN FOR MANY AREAS FOR A FEW HOURS AT THE BEGINNING OF  
THE EVENT. THEN, GUIDANCE SHOWS THE ENTIRE PROFILE QUICKLY   
MOISTENING AND BECOMING MORE OF A SNOW PROFILE FROM LATE TUESDAY  
MORNING [SIC] THROUGH WEDNESDAY MORNING. EVEN AFTER THIS OCCURS, THERE  
IS STILL PARTICULARLY HIGH UNCERTAINTY ABOUT HOW THINGS WILL   
PLAY OUT ACROSS COASTAL GA. AS FAR AS ACCUMULATIONS, IT IS OF  
COURSE ON EVERYONE'S MIND. BEING THAT IT'S MORE THAN 3 DAYS OUT  
AT THIS POINT, IT'S STILL A LITTLE EARLY TO CONFIDENTLY FORECAST  
ACCUMULATIONS. AT THIS JUNCTURE WE'RE BALLPARKING ONE OR TWO   
TENTHS OF AN INCH OF FREEZING RAIN ACCRETION AND 2-4" OF SNOW.   
IT STILL APPEARS THE GREATEST ICE ACCRETIONS WOULD PROBABLY BE   
IN COASTAL SOUTHEAST GA WHERE THE PRECIPITATION STAYS AS   
FREEZING RAIN LONGER THAN ELSEWHERE. ONE THING THAT IS A NEAR   
CERTAINTY IS THAT THESE ACCUMULATION FORECASTS WILL CHANGE   
BETWEEN NOW AND TUESDAY NIGHT.  
  
THE INITIAL PRECIPITATION SHOULD TAPER OFF WEDNESDAY MORNING.  
TEMPS WEDNESDAY AND WEDNESDAY NIGHT WILL BE QUITE COLD,  
ESPECIALLY IF WE HAVE SNOWPACK. WE COULD SEE SOME SUNSHINE BY  
LATE WEDNESDAY AFTERNOON, BUT PROBABLY NOT ENOUGH TO FULLY MELT  
ANY ACCUMULATED PRECIPITATION. HIGHS MIGHT RISE A FEW DEGREES  
ABOVE FREEZING. WEDNESDAY NIGHT LOWS WILL BE IN THE MIDDLE  
TEENS. WITH A FEW KNOTS OF WIND ON TOP OF THAT, WIND CHILLS MAY  
DIP BELOW 10F LATE AT NIGHT, POTENTIALLY REQUIRING AN EXTREME  
COLD WARNING.  
  
THE FORECAST FOR WEDNESDAY NIGHT THROUGH SATURDAY IS NOW A LOT  
TRICKIER THAN WE PREVIOUSLY THOUGHT. MODELS ARE STARTING TO SHOW  
ADDITIONAL SHORTWAVES MOVING THROUGH THE SOUTHEAST DURING THIS  
TIME, WITH A POSSIBLE COASTAL TROUGH DEVELOPING THURSDAY OR  
THURSDAY NIGHT. QUITE A FEW MODELS ARE NOW SHOWING A FEW TENTHS  
OF AN INCH OF QPF THURSDAY THROUGH FRIDAY. WITH ARCTIC HIGH  
PRESSURE STILL IN PLACE, SOUNDINGS SHOW THAT SOME OF THIS COULD  
FALL AS FREEZING RAIN. WE ADDED ZR TO THE FORECAST DURING THIS  
TIME FRAME, THOUGH THERE REMAINS A LOT OF UNCERTAINTY ABOUT WHEN  
THIS WOULD OCCUR. IF WE DO GET A PROLONGED PERIOD OF FREEZING  
RAIN ON TOP OF ACCUMULATING SNOWFALL, THIS WOULD RESULT IN  
SIGNIFICANT IMPACTS THROUGH MUCH OF THE WEEK.

[HWY316wx]

For the GA guys out of FFC:

 

.LONG TERM...
(Monday morning through next Friday)
Issued at 324 PM EST Sat Jan 18 2025

For an excellent analysis of the expected conditions and
uncertainties going into the system on Tuesday, please refer to the
previous long term discussion issued during the early morning hours.

Before diving into the winter precipitation potential, lets address
the extreme cold expected for north and central GA on Monday morning.
Temperatures across north GA are still expected to drop into the
single digits in far north GA/the mountains and near 20 in the far
southern portions of the CWA. Winds of 10 to 15 mph, gusting to 20
mph, mean temperatures will likely be well within at least extreme
cold advisory range if not warning range. Given confidence in this
outcome, a watch is necessary for areas along and north of I20 and
I85.

There are a few updates to the forecast as it pertains to model
variability and trends for wintery precip on Tuesday:

First off, global scale models have begun to come further in
agreement in Gulf Low development. This has dropped our probability
of widespread 0" snowfall amounts from around 30% (as of yesterday
1/17) to the 10th percentile. In other words confidence has increased
that at least some snowfall is expected across central GA.

Second, winter precip onset time has begun to move into the hires
model space. NAM12km has run hot (or should I say cold) with snow
coverage and the northward extent of 850mb/700mb moisture advection.
While not completely out of the realm of possibility, the forecast is
likely to continue to change as more Hires guidance comes into
range.

Third, precipitation accumulations vary significantly depending on
the northward extend of mid level moisture and the strength of the
sfc low. NBM inner quartile range for snow amounts sits from trace
amounts south of the Columbus-Macon line to widespread 2-4" across
much of central GA. (Two things to recall with this system, the
highest probs for snow are actually south of the metro and model
trends have slightly shifted wetter.) The 10th-90th range continues
to hang around 10". Given the large spread in ensemble members,
deterministic forecasts of snowfall will remain variable. Therefore,
will continue to recommend watching probabilistic guidance over
deterministic.

[calculus1]

I think one of the most common posts on our site is …

“The next 24 hours will be really important in determining … [fill in the blank].”

That same statement is made whether we are ten days away from the fever-dream storm, five days away from a possible storm, or 1 day away from an impending storm. This makes me wonder which 24-hour is not really important because that’s the one in which we can all take a breather and not live and die by each model run. Please let me know when we have determined which 24-hour period that is. Until then, I will be waiting anxiously on the next run of the … [fill in the blank] … model.

[GaWx]

Today’s Euro Weekly run in the SE for Jan 20-26 is the coldest yet and would easily mean by far the coldest week of the winter to date with 15-18F BN in most of VA/NC/SC/GA/AL/NW FL! That equates to a mean of 25-33F! That means that the bulk of the active posters are forecasted to be in/near the Jan normals for Chicago for N areas like RDU/GSO and St. Louis for more S areas like CHS:

 

[lilj4425]

We must be between model runs right now. 

[Brick Tamland]

4 minutes ago, lilj4425 said:

We must be between model runs right now. 

NAM is running now.

[jburns]

10 minutes ago, calculus1 said:

I think one of the most common posts on our site is …

“The next 24 hours will be really important in determining … [fill in the blank].”

That same statement is made whether we are ten days away from the fever-dream storm, five days away from a possible storm, or 1 day away from an impending storm. This makes me wonder which 24-hour is not really important because that’s the one in which we can all take a breather and not live and die by each model run. Please let me know when we have determined which 24-hour period that is. Until then, I will be waiting anxiously on the next run of the … [fill in the blank] … model.

I’m on it.

 

TUESDAY!!!!

[lilj4425]

11 minutes ago, jburns said:

I’m on it.

 

TUESDAY!!!!

That’s literally the equation it takes for it to snow here nowadays.

[jburns]

1 minute ago, lilj4425 said:

That’s literally the equation it takes for it to snow here nowadays.

You should have seen it before I reduced it.

[Brick Tamland]

Someone get the NAM and energy drink. It is taking forever.

[yotaman]

7 minutes ago, Brick Tamland said:

Someone get the NAM and energy drink. It is taking forever.

You going to stay up from now until Tuesday night?

[wncsnow]

NAM is better than 18Z and similar to the Euro with precip amounts 

[wncsnow]

[Brick Tamland]

[suzook]

Sleetfest/freezing rain for the coast on the nam. Still not putting much stock in it, until tomorrow evening.

[StantonParkHoya]

Just now, suzook said:

Sleetfest/freezing rain for the coast on the nam. Still not putting much stock in it, until tomorrow evening.

NC is all snow

[Brick Tamland]

Something looks wonky with the NAM totals. Seems it would be more in central NC based on where the snow was showing.

[wncsnow]

Just now, Brick Tamland said:

Something looks wonky with the NAM totals. Seems it would be more in central NC based on where the snow was showing.

Dry air Brick. Check these dewpoints. 

[suzook]

5 minutes ago, StantonParkHoya said:

NC is all snow

LMFAO, this ain't happening. 17 inches in northern Florida. Like I said, throw this out.

[Leesville Wx Hawk]

If snowing, ratios would likely approach 20:1 say at RDU therefore it would not surprise me if RDU got an inch or 2. Higher totals south and east. Still time to iron out details.


.

[metalicwx367]

3 minutes ago, suzook said:

LMFAO, this ain't happening. 17 inches in northern Florida 

The NAM snowmap and a couple of other models on tropical tidbits counts all frozen precip as snow. That map is not an accurate depiction as all of Southern GA and Northern Florida was freezing rain during that run. Here's a more accurate map. 

[jburns]

9 minutes ago, suzook said:

LMFAO, this ain't happening. 17 inches in northern Florida. Like I said, throw this out.

Psst……that 17 is in South Georgia.

[suzook]

5 minutes ago, metalicwx367 said:

The NAM snowmap and a couple of other models on tropical tidbits counts all frozen precip as snow. That map is not an accurate depiction as all of Southern GA and Northern Florida was freezing rain during that run. Here's a more accurate map. 

Almost an inch and a half of zr....what a disaster that would be.

[suzook]

1 minute ago, jburns said:

Psst……that 17 is in South Georgia.

A lot of ice.

[CaryWx]

A word to the wise--Don't take snow/ice totals too seriously at 84hrs on the NAM

[metalicwx367]

2 minutes ago, suzook said:

Almost an inch and a half of zr....what a disaster that would be.

Yeah it'll probably take out the rest of the trees that are left standing here that Helene's 100MPH wind gusts didn't take out.