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February Mid/long Range Winter Discussion


TARHEELPROGRAMMER

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Euro and Ukmet arent exactly in the same camp. The ukmet goes negative tilt with a long wave trough over the mississippi river. The euro isn't nearly that aggressive, and would still imply a front end snow/ice threat for some area's. 

 

Also, the euro is sending the surface low right into where the heart of an insitu wedge would be. I'm not buying that at this point. It should either cut west of the apps, or jump more towards the coast. IMO

 

 

Also, The euro has my temp at 29/11 Monday morning when precip starts, at 1pm i'm at 30/25, at 7pm: 31/30 and at 1am 35/34.

 

So it essentially shows zero cooling from wetbulbing... I'm definitely not buying that.

 

any time there are temps progged to be in the 30s with dewpoints in the teens and moisture around it gets my attention, so with temps in the upper 20s and dewpoints that low if there is any precip around you'd think the wedge would lock in for a while, at least, even if it does eventually warm up

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This low track is in no way favorable for central NC. Sure squeeze some ice out maybe.  Even western areas this isn't the storm for us.  Its a TN and VA north storm.

wnc I think will do well with this storm, no way it cuts due to the large H pressure, I 95 Special  I think N.GA and extreme Upstate in business also

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Is it just me or is this system trending towards a 1/22 scenario? Hybrid miller A/B, CAD, copious QPF

I honestly expect to see the s/e trend on the euro to continue and the CAD show stronger in future model runs. Mostly because of the extreme cold that is in place before the storm. Again, models have a hard time with CAD at this time range.  

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That is what I was thinking could happen, too. A mix bag event, but might be colder this time since we have colder air in place longer beforehand.

 

The cold air at the surface isn't the issue so much as it is the warm air, for this to be a big snowstorm we need the SLP to track way south and keep the warm noses away....otherwise crippling ice storm and who wants that?

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Euro actually hangs on with the parent high longer and actually is more impressive with the wedge during the day Monday..as it keeps temps sub freezing even without precip into the afternoon. The euro appears to wrongly drive the surface low straight into the wedge which models often do..which ca uses instant doubts in its surface temps.

Once again it really looks like the warming being shown is unrealistic. The Canadian and euro actually aren't that far off pressure wise with the low and parent high. The Canadian though is much colder and much more likely to be right. It shows the wedge extending up to at least 925mb...easily deep enough to resist temps warming....especially against modest 850m temps. The euro is warmer at 850 but even 6 or 7c probably wouldn't be enough to overcome the depth and degree of the boundary layer. However since the euro wants to drive the low straight into the wedge it's probably a bit too warm at that level.

So the way I see it I see nothing on the euro or any of the other guidance that makes me believe temps will warm up in cad regions from north ga into the western carolinas to prevent significant icing. The bigger question to me is just how much total precip there will be.

 

Great analysis, and I firmly agree.  The Euro and UKMet actually are further apart than the GFS/GGEM.  Right now you have your likely bookend solutions, with the GFS progressive bias on display while the Euro tends to over amp primary lows.

 

A few other points:

 

1) The euro is quite a bit slower than the GGEM/GFS, which allows the wedge to erode slightly more and push the primary further north.  If the old moniker about the ECMWF "holding back the shortwave" holds true here, that could make a huge difference.

 

2) This is a no joke cold air mass.  If I go from 12 to 48 Fahrenheit in less than 24 hours as the Euro is suggesting, that would be close to a record rise in this part of the world without full sunshine.  That alone keeps me very skeptical.  The GGEM shows a much more "natural" progression of temps.

 

3) This is still really really far out to worry about anything other than the fact there is energy and cold air around.  Sure, we don't have a 50/50 low modeled, but the piedmont and foothills have done more with less.

 

Agree with other posters that an ice storm is certainly on the table.

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KGSP Afternoon AFD

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...

AS OF 235 PM WEDNESDAY...NOT MUCH HAS CHANGED RELATIVE TO FORECAST

CONFIDENCE...WHICH STARTS OUT HIGH AS THE FCST IS DRY FOR

SUNDAY...BUT RAPIDLY GOES DOWNHILL AS THE NEXT SYSTEM APPROACHES

SUNDAY NIGHT.

THE MAIN PROBLEM IS THAT THE DETERMINISTIC GUIDANCE OUT BEYOND 00Z

MONDAY HAS SIGNIFICANT DIFFERENCES WITH REGARD TO HOW DEEP/STRONG

THE NEXT SYSTEM WILL BE AS IT COMES OUT OF THE PLAINS AND ACROSS THE

TN VALLEY/SOUTHEAST ON MONDAY AND INTO TUESDAY. THE ECMWF DIGS THE

UPPER TROF THE MOST AND CLOSES OFF A LOW AT 500 MB. WITH ITS

STRONGER SYSTEM...THERE IS MORE OF A CHANCE FOR STRONG WARM

ADVECTION OUT AHEAD OF THE SYSTEM TO PULL UP CONSIDERABLY MORE WARM

AIR...AND MOISTURE...ACROSS THE CAROLINAS MONDAY NIGHT INTO TUESDAY.

THE ECMWF MIGHT EVEN SUGGEST A HEAVY RAIN/FLOODING THREAT ACROSS THE

PIEDMONT IF IT WORKS OUT. MEANWHILE...THE OPERATIONAL GFS IS MUCH

LESS AMPLIFIED...AS IS THE CANADIAN. THE GFS HAS ONLY A WEAK SURFACE

LOW MOVING ALONG AN OLD FRONT ACROSS THE SOUTHEAST. WHILE THIS LOOKS

LESS IMPRESSIVE DYNAMICALLY...IT COULD ACTUALLY BE MORE OF A

PROBLEM...AS THE WEAKER SYSTEM WOULD HAVE LESS WARM ADVECTION ALOFT

AND WOULD KEEP A COLDER TEMP PROFILE ACROSS THE REGION. THE GFS

PATTERN IS ACTUALLY A FAVORABLE ONE FOR HEAVY SNOW ACROSS THE

WESTERN CAROLINAS AS COLD ENOUGH AIR WOULD STAY IN PLACE WHILE

ISENTROPIC LIFT AND LOW/MID LEVEL FRONTOGENESIS PROVIDE THE FORCING.

CONFIDENCE IS HIGHEST IN PRECIP ONSET AND PROBABILITY. THINK THAT

PRECIP SHOULD BEGIN TO DEVELOP FROM THE WEST AFTER 00Z MONDAY...AND

WILL SPREAD EAST ACROSS THE MTNS OVERNIGHT...AND THEN E OF THE BLUE

RIDGE MONDAY MORNING. THE PREPONDERANCE OF THE GUIDANCE SUGGESTS

THAT WE SHOULD RAISE THE PRECIP PROBABILITY INTO THE LIKELY RANGE

FROM WEST TO EAST MONDAY AFTERNOON AND THEN KEEP IT LIKELY MONDAY

NIGHT. THAT BEING SAID...CONFIDENCE IS MODERATE THAT WE WILL HAVE A

PRECIP-TYPE PROBLEM AT ONSET MONDAY EVEN IF THE ECMWF IS CORRECT

WITH ITS MORE AMPLIFIED PATTERN AND EVENTUAL CHANGEOVER TO RAIN.

THIS MAY CAUSE PROBLEMS ACROSS THE REGION THAT WILL HAVE TO BE

ADDRESSED IN LATER ISSUANCES. AT LEAST THE IMPACT MIGHT BE LESSENED

BY THE PRESIDENTS DAY HOLIDAY. WILL MENTION THIS IN THE HWO. WE ARE

LEAST CONFIDENT IN THE PRECIP TYPE FOR MONDAY NIGHT...WHICH IS KEY

TO WHETHER OR NOT WE HAVE A WINTER STORM OR JUST A NUISANCE EVENT.

THE GEFS PLUME DIAGRAMS ARE MOST INDICATIVE OF THE PROBLEM...WITH

QPF GREATER THAN 1.5 INCHES LIQUID IN MANY ENSEMBLE MEMBERS...BUT

OTHER ENSEMBLE MEMBERS WITH MERE HUNDREDTHS. EVEN THOUGH UNCERTAINTY

IS HIGH...IT SEEMS MOST LIKELY THAT PRECIP WILL GRADUALLY CHANGE

OVER TO RAIN ON TUESDAY MORNING. STAY TUNED.

THE REST OF THE MEDIUM RANGE LOOKS RELATIVELY BENIGN. THERE WILL

LIKELY BE A PERIOD OF NW FLOW SNOW ON THE BACK SIDE OF THE SYSTEM

LATE TUESDAY AND TUESDAY NIGHT. KEPT WEDNESDAY DRY AS HIGH PRESSURE

MOVES ACROSS THE SOUTHEAST AND THE NEXT NRN STREAM CLIPPER STAYS

WELL TO THE N.

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Any one looked at the French model. It has done pretty well. 

 

It's cold with precipitation breaking out by 114.  That model let me down, it took until the day of the last event to finally let go of the precip getting into my area.  In theory extrapolated, it would be a Winter storm even South of CAE.

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It's cold with precipitation breaking out by 114.  That model let me down, it took until the day of the last event to finally let go of the precip getting into my area.

 

Yeah, but it was pretty close with the SLP track/placement from several days out, to the best my recollection.  I mean, I don't remember ever seeing it waaaaaaaaaaaaaaay offshore like some of the other models tried to do, not getting any precip inland.

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Yeah, but it was pretty close with the SLP track/placement from several days out, to the best my recollection.  I mean, I don't remember ever seeing it waaaaaaaaaaaaaaay offshore like some of the other models tried to do, not getting any precip inland.

 

If anything, it had the low too close to the coast for a big chunk of forecast time.  But with that said, I'll throw some maps up in a few from the 12z run.

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Euro ensembles are less amped than the op and look a little flatter compared to the 0z ensembles. The control run now has an apps runner.

My thoughts on the Euro Ens mean....the 12z is a little slower with the wave (compared to 00z Euro Ens)....so, in accounting for this in the comparison, overall it looked like the amplitude of the wave was similar, but not quite as deep (slightly weaker) in the end, which is notable considering that the mean should naturally get stronger as we get closer in time.  It was a little stronger with the damming, and a little colder 

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Interesting that the Euro Control is an apps runner, but it keeps CAD regions of GA/SC below freezing for all of the precip, which is widespread 1 to 2 inches of liquid. The Freezing line runs from just south of Charlotte to the northeastern burbs of Atlanta as of 1am Tuesday when most of the precip has already moved through.

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Matthew East said the Euro shifted south. Sounds like he doesn't buy the UKMET.

 

(1/2) 12z model thoughts... UKMET remains in its own world. 12z Euro shifted south. Many ensemble members further south than operational.

 

(2/3) Canad. essentially held serve, GFS/ CAN sig. hits of winter weather in CAD areas. NO CHANGES from me. Favor low track from AL to E NC.

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My thoughts on the Euro Ens mean....the 12z is a little slower with the wave (compared to 00z Euro Ens)....so, in accounting for this in the comparison, overall it looked like the amplitude of the wave was similar, but not quite as deep (slightly weaker) in the end, which is notable considering that the mean should naturally get stronger as we get closer in time. It was a little stronger with the damming, and a little colder

it actually looks like less of a storm signal compared to 0z. Very odd run ad odd system.
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