Christmas Storm V

[GaffneyPeach]

From GSP (updated 6:43 am)

.NEAR TERM /THROUGH TONIGHT/...THE NAM AND GFS AGREE THAT MOST...THOUGH NOT ALL...OF THE ENERGYWITH THE SRN STREAM LOW NOW MOVING ACROSS NEW MEXICO WILL DROP SOUTHOF THE REGION. ONE THING I FIND INTERESTING IS THAT PCPN IS MOREWIDESPREAD THE PROGGED BY EITHER MODEL ACROSS SE KS AND SW MO ATTM.THIS IS THE RESULT OF FORCING ASSOCIATED WITH SOME OF THE ENERGYLIFTING OUT OF THE SRN PLAINS AND PHASING WITH THE SHORT WAVE NOWDIVING ACROSS SOUTH DAKOTA. THIS WILL BE SOMETHING TO WATCH AS THEEXPANDING AREA OF PCPN COULD BE A SIGN OF A WETTER SYSTEM MOVINGTOWARD THE AREA CHRISTMAS MORNING.

[oconeexman]

Points to remember:

1 - Most systems over the past few months have overperformed with precipitation. I know this system has a different setup than the previous ones, but it is worth watching.

2 - The models have a tendency to try to play catch-up in the 24 hours prior to a storm and precip amounts tend to increase. Don't forget that going from .2 to .3 inches of precip can cause an extra inch of snow or more with higher ratios.

3 - Shifts of 20-30 miles would not be out of the ordinary in this timeframe. With a sharp cut-off of good moisture on the west side predicted, this could take away or add some good snow for some major cities (CLT, GSO, RDU, etc...)

4 - Systems have also moved in faster than models have predicted. This may have been model bias with clipper systems, but this could have an impact on our northern stream energy and timing of a possible phase.

With at least some snow predicted for areas of the southeast, I know I will still be keeping an eye on the weather. I'm trying not to wishcast but to at least mention what I've noticed in the past. Merry Christmas everyone!!

I agree with those thoughts and observations 1000%!

Wetter than forecast is a good thing and is what we've had imby lately!

[FLO]

For Columbia. Based on the latest models, not sure how this could be correct.

SHORT TERM /SATURDAY THROUGH SUNDAY/...

CONFIDENCE NOW HIGH FOR MAINLY A RAIN EVENT ACROSS THE MIDLANDS OF

SOUTH CAROLINA AND EAST CENTRAL GEORGIA...

MODELS NOW IN GOOD AGREEMENT. UPPER TROUGH OVER THE UPPER

MIDWEST/GREAT LAKES...WILL REMAIN POSITIVELY TILTED AS IT TRACKS

EAST-SOUTHEAST ACROSS KENTUCKY/CAROLINAS THROUGH SUNDAY. SHORT

WAVE OVER THE SOUTHERN PLAINS WILL CONTINUE TO TRACK SOUTHEAST

ALONG THE NORTHERN GULF OF MEXICO SATURDAY...AND TRIGGER WEAK

SURFACE CYCLOGENESIS. THE MODEL CONSENSUS SURFACE LOW PRESSURE TRACK

IS EAST-NORTHEAST ACROSS NORTHERN FLORIDA AND RAPIDLY NORTHEAST OF THE

CAROLINA COAST...TOO FAR NORTH AND FAST FOR SIGNIFICANT SNOWFALL

FOR THE MIDLANDS. THE MUCH STRONGER SURFACE CYCLOGENESIS WILL

OCCUR ALONG THE MID ATLANTIC COASTLINE LATER ON SUNDAY AS SYSTEM

PHASES WITH UPPER LEVEL TROUGH.

MODEL SOUNDINGS SUPPORT MORE RAIN THAN SNOW WITH IMMEDIATE

SURFACE LAYERS MAINLY ABOVE ZERO. PARTIAL THICKNESSES AND MODELS

SOUNDINGS SUPPORT HIGHER CHANCE SNOW NORTH AND WEST OF COLUMBIA

LATE SATURDAY AND SATURDAY NIGHT. STRONGEST SYNOPTIC LIFT SATURDAY

EVENING AS UPPER LEVEL DIVERGENCE INCREASES AHEAD OF APPROACHING

SHORT WAVE TROUGH IN WESTERN GEORGIA. AS 850MB LOW MOVES OFFSHORE

EARLY SUNDAY COLD ADVECTION DEVELOPS AND SOUNDINGS SUPPORT SNOW

FLURRIES/OR FREEZING DRIZZLE ACROSS THE REGION AS MOISTURE BECOMES MORE

SHALLOW DURING THE DAY. ANY SNOW ACCUMULATION WILL REMAIN ACROSS

THE NORTH MIDLANDS/PEE DEE AND WILL LIKELY BE QUITE LIGHT. LITTLE

OR NO ACCUMULATION EXPECTED FROM THE CENTRAL MIDLANDS TO THE

CENTRAL SAVANNAH RIVER AREA. HIGH TEMPERATURES SATURDAY RANGING

FROM THE UPPER 30S NORTH TO NEAR 50 SOUTH. LOW SATURDAY NIGHT

CLOSE TO CONSENSUS IN THE UPPER 20S TO MID 30S. HIGHS SUNDAY ONLY

IN THE UPPER 30S TO LOWER 40S.

[Brick Tamland]

Love that the precip is more right now than the models showed. RAH says we could get an inch here with snow starting Christmas day. That's about all I can ask for. Beggers can't be choosers.

SHORT TERM /SATURDAY THROUGH THROUGH MONDAY/...

-- Changed Discussion --AS OF 340 AM FRIDAY...

STILL APPEARS AN ACCUMULATING SNOW EVENT PROBABLE FOR MUCH OF

CENTRAL NC THOUGH AMOUNTS WILL BE GENERALLY ON THE LIGHT SIDE.

STILL APPEARS BAND OF HEAVIER SNOW WILL OCCUR JUST EAST OF OUR

REGION. MODEL GUIDANCE APPEARS TO HAVE STABILIZE THOUGH TIMING

DIFFERENCES AND AMOUNT OF PRECIP EXPECTED STILL VARIABLE.

SYNOPTIC SCALE...DEEP UPPER LEVEL LOW OVER THE GREAT LAKES PROJECTED

TO DEEPEN AND DROP SOUTHWARD SATURDAY INTO SUNDAY. THIS DEEPENING IS

IN RESPONSE TO A DECENT UPPER LEVEL JET DIVING ON THE BACKSIDE OF

THE UPPER TROUGH. MID LEVEL S/W TRAVERSING THE LOWER OH VALLEY

TONIGHT WILL ADVANCE TOWARD AND CROSS OUR REGION SATURDAY. MEANWHILE

STRONG S/W IN THE SOUTHERN STREAM WILL TRAVERSE THE GULF COAST

SATURDAY THEN LIFT NE SATURDAY NIGHT INTO SUNDAY OVER THE SE U.S.

(IN RESPONSE TO THE DIGGING UPPER LOW LEVEL LOW TO ITS NORTH-NW).

UPPER LEVEL JET WILL BE EXITING OFF THE NORTHERN MID ATLANTIC COAST

LATE SATURDAY NIGHT/SUNDAY MORNING PLACING BEST UPPER DIVERGENCE

OVER THE NC COASTAL PLAIN.

MOISTURE...AIR MASS WILL BE SUFFICIENTLY MOIST TO SUPPORT

PRECIP...ESPECIALLY SATURDAY AFTERNOON THROUGH SUNDAY MORNING ACROSS

THE SOUTHERN AND EASTERN COUNTIES. DRY SUB-CLOUD LAYER IN THE WEST

SATURDAY MORNING MAY CAUSE INITIAL PRECIP TO EVAPORATE BEFORE

REACHING THE GROUND....LIMITING PRECIP AMOUNTS. BEST 850MB MOISTURE

TRANSPORT PROGGED TO OCCUR OFFSHORE SATURDAY NIGHT INTO SUNDAY SO

MOISTURE ADVECTION LATE SATURDAY INTO SUNDAY INTO CENTRAL NC APPEARS

TO BE A NON-FACTOR.

TRACK OF SURFACE LOW...MODELS HAVE COME INTO DECENT AGREEMENT WITH

MAIN SURFACE LOW ASSOCIATED WITH THE SOUTHERN STREAM S/W TRACKING

FROM THE NORTHERN GULF...ACROSS THE NORTHERN FL PENINSULA AND INTO

THE SE ATLANTIC LATE SATURDAY THROUGH SUNDAY MORNING. THIS TRACK

HISTORICALLY TOO FAR SOUTH TO SUGGEST A THREAT FOR HEAVY SNOW ACROSS

CENTRAL NC...ESPECIALLY THE PIEDMONT COUNTIES. MODELS SUGGEST

SURFACE LOW TRACK OFFSHORE SUNDAY VERSUS A TRACK CLOSER TO THE COAST

ADVERTISE A FEW DAYS AGO. THIS CURRENT TRACK ALSO SUGGEST POTENTIAL

FOR HEAVIER PRECIP TO OCCUR CLOSER TO THE COAST VERSUS THE INTERIOR

COUNTIES.

TEMP PROFILE/PARTIAL THICKNESSES...TEMP PROFILE ALOFT PLUS PARTIAL

THICKNESSES METHOD SUGGEST ANY PRECIP SATURDAY MORNING SHOULD START

OUT AS LIGHT SNOW. AS ELUDED TO IN FRIDAY AFTERNOON

DISCUSSION...MODELS DEPICT A SHALLOW WARM LAYER NEAR THE SURFACE

SATURDAY AFTERNOON IN RESPONSE TO WEAK SURFACE WAVE ASSOCIATED WITH

THE NORTHERN STREAM S/W APPROACHING AND CROSSING OUR REGION. THERE

APPEARS TO BE SUFFICIENT DEPTH TO THIS SHALLOW LAYER TO CAUSE PRECIP

TO FALL IN THE FORM OF RAIN/SNOW MIX ACROSS MOST OF THE PIEDMONT

SATURDAY AFTERNOON WITH A COLD RAIN ACROSS THE SOUTH. THIS WILL

LIMIT INITIAL SNOW ACCUMULATION LATE SATURDAY AS WELL. SHALLOW WARM

LAYER WASHES OUT AS INITIAL WAVE EXITS THE REGION. WITH PARTIALS

TRENDING TOWARD SNOW BY SATURDAY EVENING ACROSS MOST OF THE

REGION...LAST TO CHANGE IN THE FAR E-SE...BUT PRIOR TO MIDNIGHT.

PRECIP TIMING/TYPE AND AMOUNT...STILL APPEARS THAT LIGHT PRECIP WILL

OCCUR SATURDAY MORNING IN THE WEST...THEN OVERSPREAD THE REST OF THE

REGION SATURDAY AFTERNOON. AMOUNTS WILL BE LIGHT WITH AMOUNTS

THROUGH 6 PM SATURDAY A TENTH OF AN INCH OR LESS. LIGHT SNOW

EXPECTED SATURDAY MORNING THEN TRANSITIONING TO RAIN/SNOW MIX OR

JUST LIGHT RAIN IN THE SOUTH SATURDAY AFTERNOON. EVEN IF SHALLOW

WARM LAYER DOES NOT MATERIALIZE OR VERY SHALLOW...PRECIP AMOUNTS

SHOULD REMAIN LIGHT ENOUGH TO PRECLUDE ANY APPRECIABLE LIGHT SNOW

ACCUMULATION.

BULK OF PRECIP OCCURS SATURDAY NIGHT INTO SUNDAY MORNING...MAINLY

OVER THE FAR SOUTH AND EASTERN COUNTIES WHERE MID LEVEL CONFLUENCE

AHEAD OF MID LEVEL TROUGH PROJECTED TO BE GREATEST. USED H P C

PRECIP GUIDANCE SATURDAY NIGHT INTO SUNDAY WITH A SLIGHT ADJUSTMENT

UPWARD IN THE COASTAL PLAIN TO ACCOUNT FOR BETTER DYNAMICS. USING A

12-TO-1 RATIO EQUATES TO SNOW AMOUNTS OF 2-3 INCHES IN THE COASTAL

PLAIN AND AN INCH OR LESS ELSEWHERE (ABOUT AN INCH IN THE TRIANGLE

REGION...LESS THAN AN INCH IN TH TRIAD). AFTER COLLABORATION WITH

OFFICES TO OUR EAST AND SINCE PROJECTED AMOUNTS NOT QUITE TO WINTER

STORM CRITERIA AND FORECAST CONFIDENCE MARGINAL (CONFIDENCE HIGH

THAT WE WILL SEE SNOW, CONFIDENCE LOWER THAN NORMAL FOR

AMOUNTS)...WILL NOT ISSUE A WATCH WITH THIS PACKAGE.

[Psalm 148:8]

FFC seems to be hanging in there...BMX is still pondering, but think possibilities are going down....however, if you view their multimedia briefing, they continue to note that this is a nowcast type of situation....they are (as we all are) monitoring the low placement, strength, and timing....all KEY factors....that could make or break a forecast....So in other words, I don't think they have any better clue than we do at the moment...looks like another day at the computer...good thing all the wrapping is done and the turkey is in the oven

[DaculaWeather]

I agree about NOWCAST. Timing is everything, moisture placement critical... this is going to be good.

[QC_Halo]

Matthews blog is updated. No video. He appears to have thrown in the towel for the most part.

http://mattheweast.blogspot.com/

No pros have discussed the GFS this morning?

[eyewall]

The one issue I am worried about for my area aside from being just west of the best QPF is still initial p-type. As RAH says if we get a bit of an initial surface wave that would be a bit of a screw job on Christmas evening.

[GreensboroWx]

Really nothing changed with the last couple of runs. We're now just hoping for a Christmas miracle.....it could happen but it's looking doubtful. I think the Triad can expect some light snow with a dusting to an inch. This will be nice since it's Christmas but a huge disappointment since it looked MUCH bigger a couple of days ago.

Oh well.....

[snowdevil]

maybe its just me but it looks like the northern energy is outrunning the southern energy?

[oconeexman]

Matthews blog is updated. No video. He appears to have thrown in the towel for the most part.

http://mattheweast.blogspot.com/

No pros have discussed the GFS this morning?

Not a pro but the 06Z GFS looks scattered and crazy, not a whole lot of qpf anywhere much. A dusting to 3" in all 3 states to the coastlines.

[Pilotwx]

Here is a link to the WV image. http://www.goes.noaa.gov/GSSLOOPS/ecwv.html

It looks like the lows are heading for LA to FL coast probably sooner than later.

But what has caught my eye is the speed of the Northern Low. I'm no met but what if the low to the North gets to the Gulf Coast first?

[eyewall]

I don't know if it is too far off what is expected. I see the northern stream feature now over SE SD and the southern stream s/w in Western TX. Yes it does look like the northern stream is slightly ahead right now though. I did noticed the 6z GFS drastically cut my QPF unfortunately.

[oconeexman]

The 12Z NAM has initialized! Time to get it's crap together!

[Psalm 148:8]

No good with upper air charts....what is up here??

[strongwxnc]

About the same thru 12. The western ridge maybe a little sharper....

Nam is running.....Anyone care enough to do some PBP?

[wolfpackmet]

You can see some of the southern energy bleeding into the northern stream...this is the over performing precip GDP was talking about.

[strongwxnc]

Everything looks a touch North through 18 hours

Placement of the s/w and the Northern Energy.

but then again me no met

Also at 24 the whole state of TENN has light returns...

[beanskip]

Hmmm. Northern stream looks a bit different at 18 hours vs. 24 hours on 6z. On 12z, it's ... how to do I describe it ... "held back." Not sure if that describes it or if it matters .....

Also, 12z RUC at 18 hours has a much different look with the northern stream -- much more consolidated.

[wolfpackmet]

Looks similar to the ooz GFS if i remember correctly.

[oconeexman]

Composite reflectivity at 21hrs

[Shawn]

We need that Northern Stream to dig further south.

EDIT: at 27 it's not THAT far away.

[strongwxnc]

Looks like 1-2" from Middle to the mountains of TENN through 24 also.

[HWY316wx]

Posting from my phone. So all I can see is what you guys post.

Something I don't like is the serious positive tilt. Something that is interesting is the amount of moisture given how moisture starved some of the models have been over the last 24 hours.

[strongwxnc]

Again the west ridge is sharper than the 06 run at 24.

[blam49er]

Here is a link to the WV image. http://www.goes.noaa...LOOPS/ecwv.html

It looks like the lows are heading for LA to FL coast probably sooner than later.

But what has caught my eye is the speed of the Northern Low. I'm no met but what if the low to the North gets to the Gulf Coast first?

Man those cloud tops are really exploding over DFW in that loop....

[oconeexman]

Looks like decent snows in Nc, N Ga and upstate from 24-27hr, good inch or two

[Shawn]

Is this low getting sheared out by hr 33 to anyone else?

[tgarren]

the northern stream is quite a bit west and deeper from the last 2 runs but not a lot of changes through 30

[beanskip]

I'm not sure if I would know a phase when I saw it, but I know this -- on 6z NAM at this hour the northern SW was 200 miles out ahead of the southern. Now it is due north of it.

Also, fwiw (probably nothing) the latest RUC has started closing off our southern stream disturbance for at least 4 hours -- first time it has done that this morning.