January 17th-18th Winter Storm Discussion

[crossthread]

SOUTHEASTERN, NC (WWAY) -- A complicated winter storm heads toward North Carolina tonight and will bring snow to places like Raleigh, Greensboro, and Charlotte. However, with warm air in place in first it will be an all rain event here in our corner of the *TIM* (Buckley) ,,( A WARM Welcome as I've seen a post or 2 from HIM here), For our "extreme NCSE members" I , well pretty sure He is a Member of this Board, Has put together a NICE video of our upcoming System...

Mentioned We *MAY* see a few flakes here as the Cold chases the rain... Hopefully 

Credits...

I think this gentelman Is ONE of the best forcasters to come into this area in a loooonnng time...

 

SOUTHEASTERN, NC (WWAY) -- A complicated winter storm heads toward North Carolina tonight and will bring snow to places like Raleigh, Greensboro, and Charlotte. However, with warm air in place in first it will be an all rain event here in our corner of the state.

Here's the timeline on what we expect to happen throughout the day. Early on, skies will be partly cloudy with temperatures quickly warming into the 70°s. By the afternoon, the rain from this storm will move closer -- arriving before sunrise as a steady, soaking rain. This rain will continue throughout the overnight period across the area as cold air starts to invade the area, dropping temperatures rapidly.

As temperatures fall into the 30°s from west to east, most of the area will continue to see rain -- but our inland-most counties (Bladen, Robeson, Sampson, Duplin) stand the chance to see some flakes falling from the sky for a brief period after midnight. Even if this happens, the ground and roadways will be much too warm to support any accumulation.

Storm Summary

• Rain overspreads the area late afternoon, lasting until after midnight.
• Temperatures start out very warm, but fall fast throughout the day/night - eventually into the mid 30's.
• This will be all rain for southeastern North Carolina with no winter weather impacts.
• Inland counties (Bladen, Robeson, Sampson, Duplin) have a chance to see a brief period of snow -- but it will not accumulate on the warm ground.
• Other parts of the state like Raleigh/Triad/Charlotte will see problems with snow accumulation.
• All precipitation is over and done with by 4am.
• Sunny skies greet us on Friday with cold air rushing in.

 

VIDEO @ link---> http://www.wwaytv3.com/blog/video-discussion-about-the-nc-winter-storm/43677

[strongwxnc]

Great post Allan. Thanks for the gut check on the RAP model. Since I live in the S-foothills this nudges are, well it is what it is.

Thanks again sir!

 

I think you guys are putting a little too much stock into the hour to hour runs of the RAP. THis model can be somewhat useful in short term trends, but I usually only use it to look at the the radar reflectivity trends, 700mb VV, and perhaps some surface pressure trends. It is notoriously bad with QPF forecasting.

 

To me things look on track, granted I am in a bit more safe (with respect to snow) area then areas to the south. As I have said, the southern NC area looked to be close to the sharp gradient on the model data, so small trends here are there could be important.

 

But I just caution about placing too much faith in the RAP or any of these rapid cycling models. The synoptic scenario laid out by the global models the last few days is happening, now lets see how things verify over the coming hours, by watching radar, satellite, surface trends. In my mind at least things are coming together as planned. The southern foothills, CLT area is going to be close, but that is how it has looked to me the whole time anyway, so no real surprise there.

 

I think the northern piedmont of NC, southern Va is where the money spot will be outside the mountains. What we need to watch is where this band sets up this evening.

[Buddy1987]

For you guys to my south, I have switched over to complete snow now in Roanoke with the green of the grass beginning to turn white already. Have faith it's coming.

[Wow]

Agree, Allan.  If you are going to look at the RAP at least compare it to several runs back to sniff out any real trend.

 

http://mag.ncep.noaa.gov/ruc/07/ruc_namer_018_700_rh_ht.gif

http://mag.ncep.noaa.gov/ruc/18/ruc_namer_007_700_rh_ht.gif

[SN_Lover]

Ill tell yall what. The wind is blowing like 10mps from the north in mooresville. Temp is dropping like a rock

[Wow]

Ill tell yall what. The wind is blowing like 10mps from the north in mooresville. Temp is dropping like a rock

Ya, down to 42. We'll see how this next slug of rain will drop temps.

[neatlburbwthrguy]

ON radar look down around Montgomery.  That's the comma's tail end.  If that's snow when it pulls through Ga. it would then depend on the angle that it's coming up.  It could slde by west of you, or through you, but you have to figure the rates and the time would be so slight you're just going to see some flakes.  If it dries up as it's coming up...then on the the next one.  T

that makes sense but the stuff going through bham should clip the northern atl burbs from say marietta to canton to perhaps dunwoody northward...

[crossthread]

If I were you I would make the 2-3 hour trip to the triangle

thinking bout it so My WIFE can SEE some snow, But She remembers 1989 here also... 22"

[a5ehren]

that makes sense but the stuff going through bham should clip the northern atl burbs from say marietta to canton to perhaps dunwoody northward...

The low is going to turn to the NE before too much longer. The stuff hitting Bham will go north of here.

[beanskip]

That's exactly what I did and that's what revealed the north trend that is clearly happened today. Maybe the RAP is wrong -- I hope so.

New 18z NAM also north of 12z NAM position with regards to the 500 low.

Agree, Allan.  If you are going to look at the RAP at least compare it to several runs back to sniff out any real trend.

 

http://mag.ncep.noaa.gov/ruc/07/ruc_namer_018_700_rh_ht.gif

http://mag.ncep.noaa.gov/ruc/18/ruc_namer_007_700_rh_ht.gif

[dsaur]

that makes sense but the stuff going through bham should clip the northern atl burbs from say marietta to canton to perhaps dunwoody northward...

Looks like it, but remember cold dry air is coming in in a hurry, and the bulk of the moisture is north of you, so it is the endless fight in Ga. with cold and warm, moist air.  This was never going to be "our" storm, though they've upped you to a few inches, so they think the snow will make it to you.  We want  some cold air in place, and gulf low coming up, and more cold rushing in.  This is just the starter course for what could be a good winters ending.  Take what this one gives you to the bank,  and be grateful.  Let those mean Carolina folks take all the snow this time, our time is coming   T

[burgertime]

That's exactly what I did and that's what revealed the north trend that is clearly happened today. Maybe the RAP is wrong -- I hope so.

New 18z NAM also north of 12z NAM position with regards to the 500 low.

 

SV snowfall maps still put roughly 2 - 4 down from CLT to you possibly 3 - 6 in Gaston county. There does appear to be a bit less around Shelby and CLT metro go figure...personally I'm not too worried. Now if it jumps anymore I'll start panicking. We'll see what the Hi-Res has to say. 

[phil882]

Thanks for this, me and Frosty have been asking for days. I will save this. I don't think much more can fall from the sky here after 6-12 inches of rain.

 

Well its not a matter of how must moisture the atmosphere has, its a simple matter of what the flow pattern over the high terrain looks like. The highest elevation of the Appalachian mountains in North Caroline are around 1.2-1.8 km up in the atmosphere. In this atmosphere thats straddling the 850 hPa height level. In strong upper level lows such as this, when in the favorable region of upper level dynamics you have an extremely difluent patter in the mid to upper levels, with strong southerly flow aloft and strong northerly flow closer to the surface (owing to the westward tilt with height of the synoptic system). We can think of effective precipitation production in several ways, due to both the rapid ascent of air parcels starting around 700 hPa and also the advection of positive vorticity as the upper level system moves overhead. However, when topography is involved you also have to think about the lowest levels of the atmosphere. Since the system is vertically tilted, the surface low pressure is further south and east which is allowing for low-level cold air advection below 700 hPa which provides the flood of cold air that will switch precipitation over to snow.

 

The problem is for a few locations just in the lee of the mountains, this same northerly flow must descend from those higher peaks to the lower elevations immediately in the lee (Marion, Morgonton, Lenior). The descending air is the adiabatic warming I have been discussing, since air parcels that sink also warm as they descend. This fights the dynamical cooling that is caused when melting snowflakes attempt to cool warmer profiles below. Thus, its a batter over which factor wins out. Those that are already located in the higher elevations don't have to worry about this adiabatic warming since the parcels don't descent when at the highest elevations, so dynamically cooling can take over faster. However, for those areas immediately in the lee in northerly flow, it might be a nasty problem that prevents precipitation from changing completely over while limiting total precipitation totals as well. 

 

This rap sounding at 00z shows everything you need to see taken just south of Marion. Notice how the profile goes unsaturated very close to the surface. This is that northerly flow descending off the mountains that acts as a warming and drying agent that prevents snowfall in these select unlucky locations. 

 

[a5ehren]

oh my bad, im in canton now...must not have edited my location...

Also, the new AFD from FFC tends to agree with you.

 

http://forecast.weather.gov/product.php?site=NWS&issuedby=FFC&product=AFD&format=CI&version=1&glossary=1

[MotoWeatherman]

FFC.update...maps is not updated at this time on their page.  We shall see....I'm no where near that bullish but will gladly eat crow.

 

.FFC WATCHES/WARNINGS/ADVISORIES...WINTER STORM WARNING UNTIL 7 AM EST FRIDAY FOR THE FOLLOWINGZONES: BARTOW...CATOOSA...CHATTOOGA...CHEROKEE...DADE...DAWSON...FANNIN...FLOYD...GILMER...GORDON...LUMPKIN...MURRAY...PICKENS...TOWNS...UNION...WALKER...WHITE...WHITFIELD.

 

IN GENERALLY...EXPECT 2-4 INCHES OFSNOW...WITH ISOLATED AMOUNTS UP TO 5 ACROSS FAR NORTH GEORGIA...ANDSMALLER AMOUNTS ACROSS THE NORTH METRO AREA. 

[phil882]

Good to see/hear from you Phil!! Someone is going to get very disappointed tonight with all these big totals getting thrown around...sad to say. Still not expecting much more than some mixing in here in NW SC maybe a brief change over which would suffice. That warm nose is a spoiler on this side of the hills and without a any CAD it's a butt to get rid of or overcome. The track is very important...not too close but not too far!

 

Yea, it appears at this juncture the main deformation band is setting up just north of upstate SC. Of course the interesting aspect is that the track of this 500 hPa low is a little bit more suppressed than the track of the March 2009 system, so the deformation band associated with the highest precipitation rates is likely to track mainly eastward rather than northeastward with perhaps some southerly component of motion as the upper level dynamics start to fall apart. So don't be surprised if there is a band that swings southwestward into the upstate briefly before everything comes to an end. 

[RaleighWx]

It is interesting to see that with each cycle today on the NAM from 00z-18z it has beefed up the accumulations in AL/NW Ga. There has already been multiple reports of 3+ inches in AL. Perhaps that trend will continue as the snow move NE!

[SN_Lover]

wow, this sounding does not look good for GSO

 

[burgertime]

Yea, it appears at this juncture the main deformation band is setting up just north of upstate SC at this juncture. Of course the interesting aspect is that the track of this 500 hPa low is a little bit more suppressed than the track of the March 2009 system, so the deformation band associated with the highest precipitation rates is likely to track mainly eastward rather than northeastward with perhaps some southerly component of motion as the upper level dynamics start to fall apart. So don't be surprised if there is a band that swings southwestward into the upstate briefly before everything comes to an end. 

 

Thanks for the info Phil. As always like with a war you wait till the end to count who really won or lost. 

[Brick Tamland]

WxSouth update:

 

 

Nothing new to report on this...My call map from yesterday looks about right. Snow has begun on Beech Mountain and will drop down through most of Western and northern NC over the next few hours, as well as eastern TN. The axis of heaviest snow looks about like my map call from yesterday with strong banding setting up tonight just northwest of the upper low itself as it travels along I-85 through... upper SC into the piedmont of NC. This will place the foothills and western PIedmont of NC initially in heavy snowfall rates, and this spreads east through the rest of the piedmont of NC and central to southern VA overnight. Usually, the highest totals and rights are right on the northwest side of the upper low , and keep in mind it will weaken slowly on it's track through eastern NC, but most folks will see decent accumulations, with 6-10" in much of western NC, 3-6" in central NC and southern VA and 2-4" further east. There could be some foot amounts somewhere in the northwest piedmont of NC, northern Mtns of NC and mtns of southwest VA.

[SBUWX23]

why? this is observed at 7am this morning.  Not even representative of whats going to happen later.

wow, this sounding does not look good for GSO

 

[franklin NCwx]

FFC.update...maps is not updated at this time on their page. We shall see....I'm no where near that bullish but will gladly eat crow.

.FFC WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 7 AM EST FRIDAY FOR THE FOLLOWING
ZONES: BARTOW...CATOOSA...CHATTOOGA...CHEROKEE...DADE...DAWSON...
FANNIN...FLOYD...GILMER...GORDON...LUMPKIN...MURRAY...PICKENS...
TOWNS...UNION...WALKER...WHITE...WHITFIELD.

IN GENERALLY...EXPECT 2-4 INCHES OF
SNOW...WITH ISOLATED AMOUNTS UP TO 5 ACROSS FAR NORTH GEORGIA...AND
SMALLER AMOUNTS ACROSS THE NORTH METRO AREA.

well i might ride up to the top of wayah bald here in macon county toniggt. 5400 ft should be a good spot

[GaStorm]

FFC.update...maps is not updated at this time on their page.  We shall see....I'm no where near that bullish but will gladly eat crow.

 

.FFC WATCHES/WARNINGS/ADVISORIES...WINTER STORM WARNING UNTIL 7 AM EST FRIDAY FOR THE FOLLOWINGZONES: BARTOW...CATOOSA...CHATTOOGA...CHEROKEE...DADE...DAWSON...FANNIN...FLOYD...GILMER...GORDON...LUMPKIN...MURRAY...PICKENS...TOWNS...UNION...WALKER...WHITE...WHITFIELD.

 

IN GENERALLY...EXPECT 2-4 INCHES OFSNOW...WITH ISOLATED AMOUNTS UP TO 5 ACROSS FAR NORTH GEORGIA...ANDSMALLER AMOUNTS ACROSS THE NORTH METRO AREA. 

 

I guess they think more wraparound as it pulls NE?

[SN_Lover]

why? this is observed at 7am this morning.  Not even representative of whats going to happen later.

Still 10C at 7AM is pretty warm. might be colder now though. 

[Moose4]

Getting weenie-nervous out here in Daleearnhardtville (~25 miles NE of uptown CLT right off I-85).  I'd still like to see us get a couple inches out of this thing...it's my daughter's 7th birthday today, and how awesome would waking up to snow on the ground and a day out of school be.  If nothing else, it'd be a good break from three days of cold rain.

[burgertime]

why? this is observed at 7am this morning.  Not even representative of whats going to happen later.

  cause it's weenie time!

 

By the way 18z Hi Res model dramatically lower with QPF compared to 12z run. Actually has good totals for the upstate out to 5 hours. It could explode over the next few frames though.

[SBUWX23]

its already 40 or lower at GSO.  The boundary layer has no effect in this storm so this does not need to be a concern

Still 10C at 7AM is pretty warm. might be colder now though. 

[NavarreDon]

GSP afternoon.

 

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...AS OF 215 PM...COMPACT UPR LOW NOW CROSSING AL ATTM...WITH ASTRENGTHENING DEFORMATION ZONE SNOW BAND ON N SIDE OF LOW ACRS NRNAL INTO S-CENTRAL TN. THERE HAVE BEEN A FEW LGTNG STRIKES IN THEBAND...INDICATIVE OF CONDITIONAL SYMMETRIC INSTABILITY (CSI). A DRYSLOT IS JUST ENTERING THE WRN EDGE OF THE CWFA AND WILL TAPER OFFTHE WARM CONVEYOR BELT RAIN SHIELD FROM WEST TO EAST THE REST OF THEAFTN INTO THE EVENING HOURS. GUIDANCE IN DECENT AGREEMENT ON THEDEFORMATION ZONE TRACKING STRAIGHT ACRS THE CWFA THIS EVENING. THE12Z NAM IN PARTICULAR SETS UP STRONG 850 MB FRONTOGENESIS WITH THEFN VECTOR CONVERGENCE RIGHT ALONG I-85. AS THE LOW WRAPS UP...ATROWAL WILL KEEPING SUPPLYING MOISTURE AND CSI INTO THE DEFORMATIONZONE AS IT CROSSES THE CWFA. A NAM CROSS SECTION PERPENDICULAR TOTHE ZONE SHOWS NEG GEOSTROPHIC EPV IN THE MID LVLS WITH THE STRONGOMEGA AND IDEAL DENDRITIC ICE GROWTH ZONE. ALL THIS MEANS THATCONDITIONS WILL SUPPORT A NARROW INTENSE BAND OF PRECIP...WHICH WILLLIKELY CHANGEOVER TO MOD-HVY SNOW. CONFIDENCE ON WHEN AND EXACTLYWHERE THE BAND SETS UP IS STILL LOW. STILL THINKING IT WILL DEVELOPALONG I-85 IN NE GA AND CONTINUE TO PROPAGATE NEWD TO THE CHARLOTTEMETRO AREA LATER THIS EVENING. LLVL CAA WILL HELP THE TRANSITIONFROM THE TOP-DOWN IN THE MTNS AND FROM THE NE TO SW ACRS THEPIEDMONT. SO STILL EXPECTING 5-8" IN THE NRN MTNS...3-5" ABV 3500FTIN THE CENTRAL MTNS AND OUT ACRS THE NC FOOTHILLS AND NW PIEDMONT.SNOW ACCUM TO THE SOUTH ARE MORE UNCERTAIN...AS IT DEPENDS ON WHENTHE CHANGEOVER OCCURS AND WHERE THE BAND SETS UP. BASED ON THETRENDS...I THINK THE CURRENT WINTER STORM WARNINGS AND WINTER WXADVISORIES LOOK GOOD.ANOTHER CONCERN IS ONGOING FLOODING/HYDRO WITHIN OUR FLOOD WATCH. ASPREVIOUSLY MENTIONED...THE HEAVY RAIN SHUD TAPER OFF FROM WEST TOEAST WITHIN THE NEXT FEW HOURS. SO SOME FLOODING MAY WORSEN BEFORERAIN ENDS...BUT THEN MAINLY BE DEALING WITH RUNOFF FROM MID EVENINGONWARD. WILL LET THE FLOOD WATCH CONTINUE FOR NOW AND ASSESS RIVERLEVELS ONCE THE RAIN TAPERS OFF/TRANSITIONS TO SNOW.ONE OTHER THING TO NOTE IS THAT LLVL WINDS WILL REALLY INCREASE ASTHE LOW CROSSES THE AREA THIS EVENING. BOTH THE NAM AND GFS 925MBWINDS ARE 40-50 KTS ACRS THE PIEDMONT AROUND 00Z. CERTAINLY EXPECTPERIOD GUSTS IN THE 25 TO 35 MPH RANGE. EVEN THESE WINDS MAY KNOCKDOWN A FEW TREES. WINDS WILL TAPER OFF LATEST IN THE MTNS. THIS MAYCOMBINE WITH HEAVY SNOW ACCUM TO DOWN TREES AND LIMBS. THESE HAZARDSWILL BE MENTIONED IN THE WINTER HAZARD PRODUCTS.

[MotoWeatherman]

 

FFC.update...maps is not updated at this time on their page.  We shall see....I'm no where near that bullish but will gladly eat crow.

 

.FFC WATCHES/WARNINGS/ADVISORIES...WINTER STORM WARNING UNTIL 7 AM EST FRIDAY FOR THE FOLLOWINGZONES: BARTOW...CATOOSA...CHATTOOGA...CHEROKEE...DADE...DAWSON...FANNIN...FLOYD...GILMER...GORDON...LUMPKIN...MURRAY...PICKENS...TOWNS...UNION...WALKER...WHITE...WHITFIELD.

 

IN GENERALLY...EXPECT 2-4 INCHES OFSNOW...WITH ISOLATED AMOUNTS UP TO 5 ACROSS FAR NORTH GEORGIA...ANDSMALLER AMOUNTS ACROSS THE NORTH METRO AREA. 

 

I guess they think more wraparound as it pulls NE?

They explain their logic here.....we sort of...

 

http://forecast.weather.gov/product.php?site=NWS&product=AFD&issuedby=FFC&glossary=1

[SBUWX23]

its time to stop looking at model qpf maps.

  cause it's weenie time!

 

By the way 18z Hi Res model dramatically lower with QPF compared to 12z run. Actually has good totals for the upstate out to 5 hours. It could explode over the next few frames though.