Potential Mid November Event

[DCMetroWinston]

What is the definition of a hard freeze? CLT has been down to 26, most of the Triad also in the middle 20s, this season.

[Stovepipe]

What is the definition of a hard freeze? CLT has been down to 26, most of the Triad also in the middle 20s, this season.

 

I think it varies by area and doesn't have an official definition.  Most of the time, as far as vegetation is concerned in the south, I think if it is in the mid 20's for at least 5 hours it is considered a hard freeze.

[superjames1992]

Yeah, Jon, I've noticed the "wetter" GFS trend over the last few runs, too.  It seems to be spitting out 0.1"+ of QPF across most of the northern Piedmont now with 850s well below 0C.  The NAM is still pretty dry (0.01-0.1").  The GGEM looks more in line with the GFS, but it's hard to say for sure with the crappy maps I'm looking at.   What did the 12z Euro show?

 

I figure it's just a deception, but I still want my flurries.

 

FWIW, RAH has updated the grids for my area and now has snow in the forecast for the first time with a 50% chance of Rain/Snow Likely on Tuesday and a 60% chance of Rain/Snow Likely Tuesday night.  Not too often you see that in November.

[calculus1]

Yeah, Jon, I've noticed the "wetter" GFS trend over the last few runs, too.  It seems to be spitting out 0.1"+ of QPF across most of the northern Piedmont now with 850s well below 0C.  The NAM is still pretty dry (0.01-0.1").  The GGEM looks more in line with the GFS, but it's hard to say for sure with the crappy maps I'm looking at.   What did the 12z Euro show?

 

...

 

The snowfall output from the Wunderground image of the ECMWF was quite paltry.  In fact, only West Virginia had anything show up, and it's hard to call that the SE.  There was some QPF output, but it skipped over the foothills/western piedmont to indicate a few hundredths in the Raleigh area.  So, in answer to your question:  Nothing.

[Naby]

Where do you get maps like that below?

 

Thanks!

 

Cold.

 

 

[packfan98]

From NWS Raleigh:

 

PRECIPITATION CHANCES:
DESPITE PRONOUNCED COLD ADVECTION IN THE WAKE OF THE FRONTAL PASSAGE
BY LATE MORNING TO EARLY AFTERNOON...STRONG DPVA ASSOC/W THE
AMPLIFYING UPPER LEVEL TROUGH JUXTAPOSED WITH STRONG LOW/MID-LEVEL
FRONTOGENESIS LATE TUE AFTERNOON AND EVENING ARE PROGGED TO BE
SUFFICIENT FOR LIGHT PRECIPITATION TO DEVELOP AND PROGRESS SOUTHWARD
THROUGH CENTRAL NC BETWEEN 18Z TUE AND 03Z WED...WITH THE BEST
CHANCE IN THE WESTERN PIEDMONT. ALL OF THE 12Z MODEL GUIDANCE
INDICATES AT LEAST A FEW HUNDREDTHS OF AN INCH OF PRECIP ALONG AND
WEST OF THE HWY 1 CORRIDOR...AND THIS HAS INCREASED CONFIDENCE IN
MEASURABLE PRECIP ENOUGH TO RAISE PRECIP CHANCES INTO THE 50-60%
RANGE ACROSS THE WESTERN PIEDMONT...WITH 30-50% ELSEWHERE. FORECAST
SOUNDINGS SHOW A NARROW WINDOW OF TIME WHERE LAYER-LIFTING ASSOC/W
THE AMPLIFYING UPPER LEVEL WAVE WILL BE SUFFICIENT FOR SATURATION TO
EXTEND INTO THE ICE NUCLEATION ZONE LATE TUE AFTERNOON AND EARLY
EVENING...IN THE PRESENCE OF THERMAL PROFILES WHERE ONLY THE LOWEST
1000-1500 FT AGL ARE EXPECTED TO BE ABOVE FREEZING. GIVEN ONGOING
COLD ADVECTION AND AT LEAST SOME DRY AIR /EVAPORATIVE COOLING
POTENTIAL/ IN THE BOUNDARY LAYER...A CHANGEOVER FROM RAIN TO SNOW
COULD OCCUR IF PRECIPITATION RATES AND DURATION ARE SUFFICIENT...AND
THIS WILL BE THE BASIS FOR MENTIONING A RAIN/SNOW MIX FOR A FEW
HOURS LATE TUE AFT/EVE. EVEN IF PRECIPITATION DEVELOPS AND PERSIST
FOR SEVERAL HOURS IN THE PRESENCE OF FAVORABLE THERMAL PROFILES...
WARM GROUND TEMPS...AN INITIALLY ABOVE FREEZING BOUNDARY LAYER...AND
THE OVERALL DURATION/INTENSITY/AMOUNT OF PRECIPITATION ARE LIKELY TO
BE INSUFFICIENT TO RESULT IN ACCUMULATION OR ANY TYPE OF SENSIBLE
IMPACT. EXPECT PRECIP CHANCES TO END FROM N-S OR NNW-SSE BY
MIDNIGHT...WITH DRY CONDITIONS THEREAFTER. -VINCENT

[Shawn]

What is the definition of a hard freeze? CLT has been down to 26, most of the Triad also in the middle 20s, this season.

 

I'm calling 28 for a few hours a hard freeze for my area in SC.  It's the coldest we will be getting so far this season and many plants and trees are still trying to do their thing.. which in a couple nights will kill it.

 

With that said, if we don't get to 28 then nevermind.

[Tacoma]

HAZARDOUS WEATHER OUTLOOKNATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC300 PM EST MON NOV 11 2013NCZ033-048>053-058-059-062>065-501-503-505-507-509-122000-AVERY-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-GRAHAM-NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-HENDERSON-CALDWELL MOUNTAINS-BURKE MOUNTAINS-MCDOWELL MOUNTAINS-RUTHERFORD MOUNTAINS-POLK MOUNTAINS-300 PM EST MON NOV 11 2013THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN NORTH CAROLINA..DAY ONE...THIS AFTERNOON AND TONIGHT.HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME..DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY...TUESDAY...LIGHT SNOW POSSIBLE. AN ARCTIC COLD FRONT WILL BRINGMUCH COLDER AIR TO THE REGION TUESDAY. LIGHT RAIN ACCOMPANYING THEFRONT WILL CHANGE TO SNOW ACROSS THE MOUNTAINS THROUGH TUESDAY. LIGHTSNOW ACCUMULATIONS WILL BE POSSIBLE...ESPECIALLY IN THE HIGHERELEVATIONS ALONG THE BORDER BETWEEN TENNESSEE AND NORTH CAROLINA.ADDITIONALLY...WIND GUSTS ON THE ORDER OF 30 TO 35 MPH WILL BEPOSSIBLE ALONG AND BEHIND THE FRONT TUESDAY AFTERNOON AND EVENING.   

[Disc]

Where do you get maps like that below?

 

Thanks!

 

http://model.weatherbell.com/

[Disc]

Greensboro. (18z not posted yet)

 

[FLweather]

Thats a decent amount from previous runs. But 18z is pretty bleak on the qpf.

Greensboro. (18z not posted yet)

 

[superjames1992]

The 18z GFS looks drier.  It still shows probable flurries and maybe a few rain/snow showers, but not a lot (<0.1" QPF).  The NAM was equally as dry.

[Naby]

http://model.weatherbell.com/

Thanks. I signed up for a free trial there but I didn't see the southeast as a geographical region in any of the GFS model products. Is that only available with a paid subscription?

[Isopycnic]

http://www.wral.com/weather/blogpost/2027272/

What is the official definition of a hard freeze?
By Larry Roberson

Posted: November 10, 2007
MIKE MOSS SAYS: Larry, There isn't really a single "official" definition of the term. In general, "hard freeze" is used to imply temperatures that are sufficiently cold, for a long enough period, to seriously damage or kill seasonal vegetation. In our area, this usually means temperatures falling into the upper 20s or lower for at least two to three hours. There are some weather service offices that have established specific criteria for a hard freeze watch or warning that may be more intense than the generic definition I just listed - for example, the Mobile AL forecast office lists criteria for its hard freeze warning as temperatures 26 degrees or lower for at least 5 hours. They intend this warning to alert people to the potential for frozen pipes, radiators, livestock and so on, not just damage to sensitive plants.

[DaculaWeather]

FFC: http://www.daculaweather.com/4_spotter_criteria.php

 

FREEZE WARNING Issued when, during the next 24 hours, there is a high degree of confidence (at least 80%) that temperatures will drop to 32 degrees (F.) or lower. These are issued on, or after March 20th in Spring, and prior to November 20th in Autumn. In Autumn, the issuance of Freeze Warnings will be discontinued prior to November 20 if temperatures fall below 28 degrees over a wide area. After November 20th, if temperatures are expected to fall low enough to cause damage (i.e. broken water pipes), a Special Weather Statement (SPS) will be issued.

[Jon]

Thanks. I signed up for a free trial there but I didn't see the southeast as a geographical region in any of the GFS model products. Is that only available with a paid subscription?

On the main model page it's on the top right "NCEP GFS"...This link is where it goes: http://models.weatherbell.com/xgfs.php

[Shawn]

Thanks. I signed up for a free trial there but I didn't see the southeast as a geographical region in any of the GFS model products. Is that only available with a paid subscription?

 

Ryan Maue has been super kind to me in the past and from what I hear he is adding a lot of new cool stuff soon.

The Weatherbell site does seem to have the best quality (graphically) and pretty fast maps these days.  There are lots of options and tons of different perspectives to view stuff all over the globe.. just takes a little fiddling around to find it all.  He has the county maps for areas of the united states generated also with totals for cities etc labled with pretty much all the models, even Euro.

[superjames1992]

I know, I know, but the 00z NAM picked up on the stripe of 0.1"+ QPF across the NC Northern Piedmont that the GFS had been hinting at earlier.

 

 

FWIW, the 00z Hi-Res NAM has a pretty good band of precipitation sweep through much of North Carolina just after sunset tomorrow.

[FLweather]

Not that it matters but wouldn't be too surprised models trend wetter with 0Z runs.

 

It does look impressive on radar and Im a little hopeful about more moisture being present later. It is a rather impressive system in the upper levels aswell.

 

But its the Rap model. Cant really tell much by precip totals. But judging by 700mb maybe a good little deformation band to setup tomorrow evening. Dunno if its too likely but possiblly moving in before noon in the triad, danville area, east of Roa,LYN.

 

[DopplerWx]

gfs still showing a chance at some snow showers for mid nc down to northern sc.  

[WidreMann]

Not that it matters but wouldn't be too surprised models trend wetter with 0Z runs.

 

It does look impressive on radar and Im a little hopeful about more moisture being present later. It is a rather impressive system in the upper levels aswell.

 

But its the Rap model. Cant really tell much by precip totals. But judging by 700mb maybe a good little deformation band to setup tomorrow evening. Dunno if its too likely but possiblly moving in before noon in the triad, danville area, east of Roa,LYN.

 

You can't just call any band of precip a deformation band.

[Martin]

RPM still showing a brief band of snow across NC 

[NCCatawba]

[Spidyr2k]

Matt East's Vidblog for today.....he always gets my vote for rational forecasting:

[RevDodd]

Matt East's Vidblog for today.....he always gets my vote for rational forecasting:

 

BAH! We're talking mid-November snow ... what use do we have for rational forecasting? 

[mackerel_sky]

Temps are ALWAYS a problem in the south . Rain today!

[Solak]

The wind map is pretty impressive this morning in locating the front...

 

http://hint.fm/wind/

[FallsLake]

Temps are ALWAYS a problem in the south . Rain today!

The primary band of precip currently looks good. But it hasn't crossed the mountains yet (for us) and that will rob a lot of the moisture. Also the temps really will be an issue because of the time of day passage.  

 

I have seen these types of setup over-perform, but hoping for over-performance is not going to work most of the time. Give me a flurry and I'll be happy.  

[1300m]

The primary band of precip currently looks good. But it hasn't crossed the mountains yet (for us) and that will rob a lot of the moisture. Also the temps really will be an issue because of the time of day passage.  

 

I have seen these types of setup over-perform, but hoping for over-performance is not going to work most of the time. Give me a flurry and I'll be happy.  

This one is going to be forced primarily by strong frontogenesis, so what is coming towards the mountains isn't what we're looking for. The band coming across the mountains will almost definitely dry up in 20 to 30kts of downslope flow - this is the direct effects of the positively tilted trough on the wind field. If our trough had been neutrally tilted, winds would have been more southwesterly, allowing moisture to be transported into the region (along with surface cyclogenesis), rather than drying up in downslope flow.

 

The only thing that may allow us to see a few token flakes today is the incredible horizontal temperature gradient (especially aloft), which results in a secondary restoring circulation - i.e. frontogenesis - which will result in a renewed area of lift just *behind* the front. Hopefully, this will result in some rain changing to snow for just an hour or so this afternoon. I think the HRRR probably has a good handle on how today's scenario will play out. It shows the secondary area of precipitation developing behind the front over VA and making it's way southward across NC. Looking at the soundings, there is probably only a 1-2 hour window for any one area to see any snow, and not all areas will see anything or may only see rain if moisture doesn't hang around long enough or if rates aren't strong enough to cool the lowest 1,000 feet or so of the atmosphere.

 

As others have already said, the strength of this fall front is the story here - and it may be strong enough to generate a few snow showers on it's own despite an otherwise unfavorable precipitation pattern.

[burgertime]

Flurries in Nashville right now.