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January 17th-18th Winter Storm Discussion

BullCityWx

By BullCityWx,
in Southeastern States

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gritsnc

gritsnc

Posted
Posted

I know that nobody really pays attention to TWC's site, but their hourly shows "heavy snow" for the Winston-Salem area on Thursday night from 9pm to 11pm and then "snow shower" till 2am. I posted a screen shot of it on FB to humor myself as I watch all of the "shares" and people freak out.

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beanskip

beanskip

Posted
Posted

And people wonder why I'm a Negative Nancy.

 

Actually, my sounding at 33 hours was a little better than I thought.

 

Date: 33 hour Eta valid 3Z FRI 18 JAN 13
Station: KEHO
Latitude:   35.26
Longitude: -81.60
-------------------------------------------------------------------------------
LEV PRES  HGHT  TEMP  DEWP  RH  DD   WETB DIR SPD THETA THE-V THE-W THE-E   W
     mb     m     C     C    %   C     C  deg knt   K     K     K     K    g/kg
-------------------------------------------------------------------------------
  0 1000   147                                                                
SFC  987   256   1.0   0.5  96  0.5   0.8   4  16 275.2 275.9 274.6 286.1  4.00
  2  950   560   0.0  -0.0 100  0.0   0.0  15  36 277.2 277.9 275.7 288.2  4.02
  3  900   993  -0.3  -0.3 100  0.0  -0.3  30  50 281.2 281.9 278.0 292.8  4.15
  4  850  1449  -1.7  -1.9  98  0.3  -1.8  28  49 284.4 285.1 279.3 295.5  3.91
  5  800  1931  -2.9  -3.3  97  0.4  -3.0  32  44 288.1 288.7 280.8 298.9  3.76
  6  750  2442  -4.3  -4.8  96  0.5  -4.5  25  39 291.9 292.5 282.3 302.4  3.57
  7  700  2983  -6.3  -7.1  94  0.8  -6.6  43  32 295.5 296.1 283.4 305.1  3.21
  8  650  3561  -8.5  -9.4  93  0.9  -8.8  93   8 299.4 299.9 284.7 308.2  2.89
  9  600  4177 -12.4 -13.7  90  1.3 -12.8 165  18 301.8 302.2 284.8 308.7  2.21
10  550  4838 -15.5 -17.1  88  1.6 -15.9 135  26 305.7 306.0 285.9 311.5  1.83
11  500  5551 -19.9 -22.0  83  2.2 -20.4 119  30 308.8 309.1 286.4 313.1  1.31
12  450  6324 -25.2 -29.6  67  4.3 -25.9 114  28 311.5 311.7 286.8 314.0  0.73
13  400  7172 -28.7 -40.1  33 11.4 -30.0 162  22 317.7 317.8 288.3 318.8  0.29
14  350  8120 -32.7 -55.6   8 22.9 -34.1 196  44 324.6 324.7 290.2 324.9  0.06
15  300  9192 -38.7 -64.5   5 25.8 -39.8 199  61 330.8 330.8 291.9 330.8  0.02
16  250 10425 -45.1                      207  67 339.0                       
17  200 11891 -52.0                      216  67 350.5                       
18  150 13732 -56.8                      236  77 372.3                       
19  100 16250 -64.0                      238  83 404.1                       
TRP                                             0                             
WND                                             0                             

Sounding variables and indices
1000-500 mb thick:      5403.77 m
Freezing level:          946.09 mb =   593.86 m =  1948.32 ft
Wetbulb zero:            946.63 mb =   588.46 m =  1930.62 ft
Precipitable water:        0.66 inches
 

 

Man NAM paints a triangle of death with no snow right over Skip and Robert. 

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Brick Tamland

Brick Tamland

Posted
Posted

WxSouth's thoughts

 

 

in between map editing and video now, but just looked at 18z NAM....its had the hot hand on this storm all along. MAJOR dump coming to all of western NC, eastern TN and with tthe cold core upper low some good snow and sleet as well in Alabama and Georgia. This thing just continues to trend stronger, stronger and stronger, for longer ...this is the trend all along. The path remains basically the ...same. If you remember March 2009 in northern Alabama, eastern TN, northern Ga and upstate SC, much of NC...then this should ring a bell. Only thing is its a faster event, in and out quickly. But when the snow comes down, it's really REALLY going to come down. Still looks like the worst of the worse will be most of western NC, eastern TN and southern half of Virginia, but with the cold core so strong and wrapped up, I think Upstate SC and northern GA gets walloped for several hours as well. The surface temps won't drop much below 33 for most areas outside the mountains until the very end, so this snow will stick mostly to trees and cartops, etc at first...but with it falling so incredibly hard for 3 to 6 hours, some areas will manage 8" or more on the ground. The mountains of TN, NC and VA will approach 12" of a very wet, heavy snow. This is extremely bad news for saturated grounds as trees branches will snap easily after 6" of wet sticky snow, and any winds will topple more trees after the storm blows by and winds pick up.
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MotoWeatherman

MotoWeatherman

Posted
Posted

ATL still looks like rain at 0z tomorrow night.

 

Date: 30 hour Eta valid 0Z FRI 18 JAN 13Station: ATLLatitude:   33.65Longitude: -84.42-------------------------------------------------------------------------------LEV PRES  HGHT  TEMP  DEWP  RH  DD   WETB DIR SPD THETA THE-V THE-W THE-E   W     mb     m     C     C    %   C     C  deg knt   K     K     K     K    g/kg-------------------------------------------------------------------------------  0 1000   103                                                                 SFC  979   276   5.9   4.8  93  1.1   5.4 297   9 280.8 281.7 279.6 296.0  5.53  2  950   520   3.2   3.2 100  0.1   3.2 308  14 280.5 281.3 278.8 294.4  5.06  3  900   957   1.4   1.4 100  0.0   1.4 347  21 283.0 283.8 279.6 296.1  4.71  4  850  1416  -0.5  -0.6 100  0.0  -0.6  17  21 285.6 286.4 280.4 297.8  4.32  5  800  1899  -2.5  -2.7  99  0.2  -2.6  17  19 288.5 289.2 281.2 299.8  3.91  6  750  2410  -4.4  -4.9  96  0.6  -4.6 347  16 291.8 292.5 282.3 302.2  3.53  7  700  2951  -6.6  -7.3  94  0.8  -6.8 349  23 295.2 295.8 283.2 304.7  3.15  8  650  3528  -8.4  -9.4  93  0.9  -8.8 353  36 299.5 300.0 284.7 308.3  2.89  9  600  4144 -12.9 -15.2  83  2.2 -13.6 341  43 301.1 301.5 284.3 307.3  1.96 10  550  4802 -17.1 -24.3  54  7.2 -18.6 330  47 303.9 304.0 284.2 307.0  0.98 11  500  5511 -20.0 -38.7  17 18.7 -22.5 321  44 308.6 308.7 285.2 309.6  0.27 12  450  6290 -22.0 -52.0   5 30.0 -24.8 302  38 315.6 315.6 287.4 315.9  0.07

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MotoWeatherman

MotoWeatherman

Posted
Posted

Per 18z NAM Rome GA should be all snow tomorrow at 0z.

 

Date: 30 hour Eta valid 0Z FRI 18 JAN 13Station: RMGLatitude:   34.35Longitude: -85.17-------------------------------------------------------------------------------LEV PRES  HGHT  TEMP  DEWP  RH  DD   WETB DIR SPD THETA THE-V THE-W THE-E   W     mb     m     C     C    %   C     C  deg knt   K     K     K     K    g/kg-------------------------------------------------------------------------------  0 1000   150                                                                 SFC  991   225   2.0   1.0  94  0.9   1.5 340  18 275.9 276.6 275.2 287.2  4.16  2  950   562  -0.0  -0.1 100  0.0  -0.0 353  35 277.2 277.8 275.7 288.1  4.00  3  900   995   0.3  -0.2  97  0.4   0.1  21  50 281.8 282.5 278.4 293.5  4.20  4  850  1454  -0.1  -0.1 100  0.0  -0.1  25  55 286.0 286.8 280.7 298.7  4.46  5  800  1938  -1.2  -1.2 100  0.0  -1.2  20  49 289.9 290.7 282.4 302.5  4.37  6  750  2451  -3.2  -3.4  98  0.2  -3.3  24  42 293.1 293.8 283.3 304.8  3.97  7  700  2995  -5.8  -6.3  97  0.5  -6.0  23  38 296.0 296.6 283.9 306.2  3.41  8  650  3572  -8.9  -9.5  95  0.7  -9.1  18  33 298.9 299.5 284.4 307.7  2.85  9  600  4189 -11.3 -12.2  93  0.9 -11.6   3  32 303.1 303.5 285.7 310.9  2.50 10  550  4853 -14.4 -15.6  91  1.2 -14.8 354  34 307.0 307.3 286.6 313.5  2.06 11  500  5569 -19.3 -21.3  84  2.0 -19.8 344  36 309.6 309.8 286.8 314.2  1.40 12  450  6341 -26.3 -29.1  78  2.7 -26.8 347  37 310.1 310.3 286.3 312.8  0.77
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NavarreDon

NavarreDon

Posted
Posted

GSP is hoisting the flag!

 

 

SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
AS OF 315 PM WEDNESDAY...A NE TO SW ORIENTED DEEP LAYER FRONTAL
BOUNDARY REMAINS STALLED OVER THE WESTERN CAROLINAS AND NE GA. PW
VALUES ALONG THE BNDRY CONTINUE TO RUN 200 TO 300 PERCENT OF NORMAL.
IN FACT...NESTS MENTIONED THIS MORNING THAT FFC/S SOUNDING THIS
MORNING HAD IT/S 4TH HIGHEST RECORDED JANUARY PW VALUE. SO THAT SAY
THAT THERE IS A SIGNIFICANT AMOUNT OF MOISTURE IN PLACE OVER THE
REGION IS AN UNDERSTATEMENT. A POTENT UPPER LOW OVER ERN TX THIS
EVENING WILL TAKE ON A NEGATIVE TILT AND LIFT ACROSS THE UPSTATE BY
TOMORROW EVENING. THE NUMERICAL MODELS GENERATE VERY HEAVY RAIN WITH
THIS FEATURE. QPF AVERAGES AROUND 3 INCHES OVER MUCH OF THE SRN AND
ERN NC MTNS...THE FOOTHILLS AND THE WESTERN PIEDMONT. CONSIDERING
THE AMAZING AMOUNT OF RAIN SOME MOUNTAIN LOCATIONS HAVE HAD OVER THE
PAST THREE DAYS...THIS EXTRA SHOT OF RAIN IS LIKELY TO CAUSE A
CONSIDERABLE AMOUNT OF STREAM AND RIVER FLOODING. THEREFORE THE
FLOOD WATCH WILL BE EXPANDED ACROSS THE REST OF THE MOUNTAINS AND
FOOTHILLS OF THE WESTERN CAROLINAS AND NORTHEAST GEORGIA. WE COULD
SEE SOME VERY HIGH RAINFALL RATES AS THE WARM CONVEYOR BELT WORKS
ACROSS THE FA DURING THE DAYTIME TMRW. A TSTM ISN/T OUT OF THE
QUESTION. CONSIDERING THE EXPECTED RATES...SOME OF THE FLOODING MAY
BE MORE OF THE FLASH FLOOD VARIETY. IN FACT...I/M STILL DEBATING IF
WE WILL ISSUE THE NEW WATCH AS A FLOOD OR FLASH FLOOD PRODUCT.

THE OTHER CONCERN AS THE LOW PASSES WILL BE SNOWFALL. THE AIRMASS
AHEAD OF THE LOW IS VERY WARM AND MOIST. IT WILL TAKE A WHILE FOR
THE PCPN TO CHANGE OVER TO SNOW. I WOULDN/T EXPECT ANY SNOW TO
DEVELOP UNTIL 18 TO 21 UTC ACROSS THE HIGHER MOUNTAIN ELEVATIONS.
THE SNOW LEVELS WILL THEN QUICKLY DROP AND WORK EASTWARD WITH TIME.
THE SREF PLUME DIAGRAMS ARE SHOWING WINTER STORM CRITERIA SNOWFALL
AT ASHEVILLE AND EVEN AT HICKORY. I HAVE UPGRADED THE WINTER STORM
WATCH TO A WARNING ACROSS MOST OF THE NC MTNS. OVER THE SOUTHWEST
MOUNTAINS THE WARMING WILL BE IN EFFECT FOR ELEVATIONS ABOVE 3500
FEET. BY THE TIME THE SNOW LEVEL MAKES IT TO THE VALLEY FLOORS IN
THOSE AREAS...I EXPECT THE HEAVIEST PCPN WILL HAVE ENDED.

THE NORTHERN MOST PART OF THE UPSTATE AND NE GA HAVE BEEN INCLUDED
IN A WINTER WEATHER ADVISORY FOR TOMORROW NIGHT. ONLY AROUND AN INCH
OF SNOW IS IN THE GRIDS...BUT IF THE NAM/S STRONGER...SLOWER AND
COLDER DEFORMATION ZONE VERIFIES...WE COULD SEE HEAVIER HEAVIER SNOW
IN THESE LOCATIONS IN WELL. I AM MORE CONFIDENT IN THE NAM TONIGHT
AS THE IT AND THE GFS HAVE COME INTO MUCH BETTER AGREEMENT. OVER THE
NORTH CAROLINA ZONES...THE NAM AND MANY SREF MEMBERS INDICATE A
PERIOD OF SNOW ACROSS THE FOOTHILLS AND PIEDMONT DURING THE EVENING
HOURS. A CROSS SECTION THROUGH THE NAM SHOWS A DEEP LAYER NEGATIVE
EPV FROM 00-03 UTC. THIS IMPLIES THE POTENTIAL FOR HEAVY BANDED
PRECIPITATION WHICH WILL HELP TO LOWER SNOW LEVELS. IN FACT...AT
THIS POINT I/D SAY CONFIDENCE IS GOOD THAT PARTS OF THE PIEDMONT
WILL SEE SNOW...THOUGH ACCUMULATING SNOW MAY BE CONFINED TO A NARROW
BAND UNDER THE BEST CSI. THE RALEIGH OFFICE IS THINKING ALONG THE
SAME LINES AND WE HAVE ISSUED A WINTER STORM WATCH FOR THESE AREAS
STARTING AT 21 UTC TOMORROW. EVEN WITH WARM GROUND...HEAVY SNOWFALL
RATES COULD CAUSE TRAVEL CONCERNS AND MAY BREAK SOME LIMBS CAUSING
POWER OUTAGES.

 

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MotoWeatherman

MotoWeatherman

Posted
Posted

18z NAM for GSP at 10pm tomorrow...looks like snow by that time...wet snow...

 

Date: 33 hour Eta valid 3Z FRI 18 JAN 13Station: GSPLatitude:   34.90Longitude: -82.22-------------------------------------------------------------------------------LEV PRES  HGHT  TEMP  DEWP  RH  DD   WETB DIR SPD THETA THE-V THE-W THE-E   W     mb     m     C     C    %   C     C  deg knt   K     K     K     K    g/kg-------------------------------------------------------------------------------  0 1000   147                                                                 SFC  985   268   2.1   1.3  94  0.8   1.8   5  18 276.5 277.2 275.7 288.1  4.27  2  950   561   0.1   0.1 100  0.0   0.1  12  36 277.3 278.0 275.9 288.4  4.05  3  900   994  -0.1  -0.1 100  0.0  -0.1  31  53 281.4 282.2 278.2 293.2  4.22  4  850  1451  -1.2  -1.3  99  0.2  -1.3  29  50 284.9 285.6 279.7 296.5  4.08  5  800  1933  -2.6  -2.8  98  0.2  -2.7  32  46 288.4 289.0 281.1 299.5  3.88  6  750  2444  -4.3  -4.7  97  0.5  -4.4  19  39 292.0 292.6 282.4 302.5  3.59  7  700  2985  -7.1  -7.7  95  0.7  -7.3  35  41 294.7 295.2 282.9 303.8  3.05  8  650  3561  -9.4 -10.1  95  0.7  -9.6  24  24 298.3 298.8 284.1 306.7  2.73  9  600  4175 -13.1 -14.4  90  1.3 -13.5 330  17 300.9 301.3 284.4 307.4  2.09 10  550  4832 -18.3 -19.9  87  1.6 -18.7  12   9 302.4 302.7 284.2 307.0  1.43
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calculus1

calculus1

Posted
Posted

I'm not liking the KHKY soundings either.  The surface temp doesn't even wet-bulb to zero at hour 33 or 36.  This is reminding me March 2009 too much at this point.

 

Date: 33 hour Eta valid 3Z FRI 18 JAN 13Station: KHKYLatitude:   35.73Longitude: -81.38-------------------------------------------------------------------------------LEV PRES  HGHT  TEMP  DEWP  RH  DD   WETB DIR SPD THETA THE-V THE-W THE-E   W     mb     m     C     C    %   C     C  deg knt   K     K     K     K    g/kg-------------------------------------------------------------------------------  0 1000   156                                                                 SFC  978   333   0.4   0.1  98  0.3   0.3 359   9 275.2 275.9 274.5 285.9  3.93  2  950   568   0.1   0.0 100  0.0   0.1  12  25 277.3 277.9 275.8 288.3  4.03  3  900  1001  -0.8  -1.0  99  0.1  -0.9  24  41 280.6 281.3 277.5 291.7  3.96  4  850  1456  -2.6  -2.9  97  0.4  -2.7  19  45 283.4 284.1 278.4 293.7  3.62  5  800  1936  -3.2  -3.6  97  0.4  -3.4  21  41 287.7 288.4 280.6 298.3  3.66  6  750  2447  -3.5  -3.9  97  0.4  -3.7   9  31 292.8 293.5 283.0 304.0  3.82  7  700  2990  -5.8  -6.6  95  0.7  -6.1  37  28 296.0 296.6 283.8 306.0  3.34  8  650  3569  -7.5  -8.2  94  0.8  -7.8  96  17 300.5 301.1 285.4 310.2  3.16  9  600  4189 -10.7 -11.8  92  1.1 -11.1 168  13 303.7 304.2 285.9 311.8  2.58 10  550  4854 -13.7 -15.1  89  1.4 -14.2 178  11 307.8 308.2 286.9 314.7  2.15 11  500  5574 -17.1 -18.8  87  1.7 -17.6 161  20 312.2 312.5 288.1 317.9  1.73 12  450  6355 -23.5 -25.5  83  2.0 -23.9 157  31 313.7 313.9 287.8 317.2  1.06 13  400  7201 -31.3 -34.2  76  2.9 -31.7 159  31 314.3 314.4 287.5 316.2  0.53 14  350  8136 -35.4 -48.7  24 13.3 -36.3 185  44 321.0 321.1 289.2 321.5  0.13 15  300  9199 -40.3 -61.2   9 21.0 -41.1 192  69 328.6 328.6 291.3 328.8  0.03 16  250 10423 -47.3                      198  78 335.7                         17  200 11878 -53.1                      210  73 348.7                         18  150 13717 -56.3                      236  76 373.1                         19  100 16238 -63.7                      238  81 404.7                        TRP                                             0                              WND                                             0                              Sounding variables and indices1000-500 mb thick:      5418.04 mFreezing level:          945.86 mb =   604.08 m =  1981.87 ftWetbulb zero:            946.07 mb =   601.48 m =  1973.34 ftPrecipitable water:        0.68 inches

 

Date: 36 hour Eta valid 6Z FRI 18 JAN 13Station: KHKYLatitude:   35.73Longitude: -81.38-------------------------------------------------------------------------------LEV PRES  HGHT  TEMP  DEWP  RH  DD   WETB DIR SPD THETA THE-V THE-W THE-E   W     mb     m     C     C    %   C     C  deg knt   K     K     K     K    g/kg-------------------------------------------------------------------------------  0 1000   174                                                                 SFC  980   336   1.3   0.5  94  0.8   1.0 326   5 276.0 276.7 275.1 287.1  4.03  2  950   586   0.6  -1.0  89  1.6  -0.1   2  17 277.8 278.4 275.7 288.1  3.73  3  900  1019  -1.9  -4.6  82  2.7  -2.9  10  29 279.5 280.1 275.6 288.0  3.02  4  850  1471  -3.7 -10.2  60  6.5  -5.8  10  39 282.3 282.6 275.7 288.3  2.07  5  800  1949  -4.7 -19.0  32 14.3  -8.4   3  45 286.2 286.4 276.3 289.4  1.07  6  750  2457  -2.8 -16.6  34 13.8  -7.0 350  43 293.5 293.8 280.4 297.8  1.39  7  700  3004  -3.9  -9.8  63  6.0  -6.1 338  35 298.2 298.7 283.8 306.1  2.59  8  650  3585  -6.9 -10.1  78  3.2  -8.1 329  30 301.2 301.7 285.2 309.6  2.74  9  600  4206 -10.5 -12.6  85  2.1 -11.2 332  25 304.0 304.4 285.9 311.6  2.43 10  550  4869 -15.2 -16.9  86  1.8 -15.7 323  27 306.1 306.4 286.0 312.0  1.84 11  500  5584 -18.4 -21.0  81  2.5 -19.1 316  37 310.5 310.8 287.2 315.3  1.44 12  450  6363 -23.8 -26.8  76  3.0 -24.4 314  36 313.3 313.5 287.6 316.5  0.95 13  400  7210 -30.6 -33.6  74  3.1 -31.0 317  35 315.3 315.4 287.8 317.2  0.56 14  350  8144 -37.8 -41.6  67  3.9 -38.1 317  39 317.8 317.9 288.3 318.9  0.28 15  300  9188 -43.7 -54.6  29 10.9 -44.2 294  37 323.7 323.8 290.0 324.0  0.08 16  250 10407 -47.2                      276  48 335.9                         17  200 11862 -53.0                      254  59 348.8                         18  150 13690 -57.8                      242  71 370.5                         19  100 16209 -63.5                      238  76 405.1                        TRP                                             0                              WND                                             0                              Sounding variables and indices1000-500 mb thick:      5410.07 mFreezing level:          937.86 mb =   691.32 m =  2268.09 ftWetbulb zero:            952.00 mb =   569.50 m =  1868.43 ftPrecipitable water:        0.49 inches
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Brick Tamland

Brick Tamland

Posted
Posted

RAH getting on board.

 

 

 

FOR THURSDAY/THURSDAY NIGHT: LATEST MODELS ARE CONVERGING ON A

SOLUTION WHICH PLACES THE RIGHT MIX OF STRONG LIFT AND INCOMING COLD

AIR AT MULTIPLE LEVELS CONDUCIVE TO WINTRY PRECIP... IN TANDEM WITH

A PATTERN OF CYCLOGENESIS WHICH FAVORS SNOW BANDING. A WINTER STORM

WATCH WILL BE ISSUED FOR NORTHERN AND WESTERN PORTIONS OF CENTRAL NC

FOR THURSDAY EVENING INTO THE NIGHT.



-SYNOPTIC SCALE FEATURES: SURFACE FRONT WILL REMAIN ACROSS SOUTH

CENTRAL AND EASTERN NC. LOW PRESSURE WILL DEVELOP AND STRENGTHEN

ALONG THE FRONT OVER CENTRAL GA THURSDAY MORNING BEFORE TRACKING TO

THE ENE ACROSS CENTRAL SC AND SOUTHEAST NC THURSDAY AFTERNOON

THROUGH EVENING... SHIFTING OFF THE SRN OUTER BANKS COAST SHORTLY

AFTER MIDNIGHT. IN THE MID LEVELS... A STRONG VORTEX OVER TX THIS

AFTERNOON WILL ABSORB NRN STREAM ENERGY AND TAKE ON A SLIGHT

NEGATIVE TILT AS IT SHIFTS ACROSS THE LOWER MISS VALLEY THROUGH

THURSDAY MORNING THEN ACROSS SE AND ERN NC THURSDAY NIGHT... STACKED

VERY CLOSELY WITH THE SURFACE AND 850 MB LOWS. MODELS HAVE COME INTO

EXCELLENT AGREEMENT ON THE TIMING AND STRENGTH OF THESE FEATURES...

INCLUDING THE NEW ECMWF WHICH AGREES WELL WITH THE SLOWER NAM. THIS

SOLUTION WAS FAVORED OVER THE SLIGHTLY SLOWER GFS.



-MOISTURE AND LIFT MECHANISMS: WE REMAIN VERY MOIST WITH STRONG LOW

LEVEL MOISTURE TRANSPORT AND MODEL-PROJECTED PRECIP WATER VALUES

HOLDING ABOVE 200 PERCENT OF NORMAL... IN THE 1.1-1.4 INCH RANGE

THROUGH THURSDAY BEFORE RAPIDLY DRYING WSW TO ENE LATE THURSDAY

NIGHT. FORCING FOR ASCENT STRENGTHENS QUICKLY WITH THE APPROACHING

SYSTEM... INCLUDING INTENSE UPPER DIVERGENCE... 150-200 METER HEIGHT

FALLS... AND STRONG LOW LEVEL MASS CONVERGENCE NEAR THE TIGHTENING

850 MB FRONTAL ZONE. SLOPED ASCENT BACK TOWARD THE NORTHWEST AND

STRONG FRONTOGENESIS ALONG WITH THE MILLER TYPE-A PATTERN FAVOR SNOW

BANDING... MOST LIKELY OCCURING ACROSS THE WRN AND NRN PIEDMONT

THURSDAY EVENING INTO THE EARLY OVERNIGHT HOURS... NW OF THE 850 MB

LOW TRACK.



-PRECIP TYPES/AMOUNTS: BASED ON THIS PATTERN... WE SHOULD EXPECT A

VERY NARROW TRANSITION ZONE FROM RAIN TO SNOW... VERY CLOSE TO THE

TRADITIONAL RAIN/SNOW LINE. EXPECT A TREND TOWARD SNOW FIRST IN THE

TRIAD VERY LATE THURSDAY AFTERNOON... SPREADING ACROSS THE REST OF

THE NRN/WRN PIEDMONT AND FAR NRN NC THROUGH THE EVENING AS THE

COLUMN COOLS. WHILE WE DO SEE SOME DRYING WELL ALOFT IN THE

EVENING... THERE IS STRONG ENOUGH LIFT AND ENOUGH MOISTURE IN THE

-10C TO -20C LAYER ALOFT TO SUPPORT A P-TYPE OF SNOW. WHILE THE

COLUMN BELOW COOLS... IT REMAIN PRECARIOUSLY CLOSE TO 0C... SUCH

THAT THE FOCUSED LIFT ACCOMPANYING THE SNOW BANDS SHOULD BE

SUFFICIENT FOR BURSTS OF SNOW. REGARDING ACCUMULATIONS... THE

SOMEWHAT MILD WEATHER OF LATE MAKES ACCUMULATIONS DIFFICULT AS SOIL

TEMPS SIT IN THE 50S IN MOST AREAS. AS SUCH... THE GREATEST SNOW

ACCUMULATION IS LIKELY TO BE ON GRASSY AND ELEVATED SURFACES. WITH

STORM TOTAL LIQUID EXPECTED TO RANGE FROM AROUND AN INCH SOUTHEAST

TO 2-2.25 INCHES IN THE TRIAD... AND FACTORING IN A SNOW-LIQUID

RATIO OF 2 TO 1 RANGING TO 4 TO 1 (LESSER VALUES WHERE A MIX OR

BRIEF TRANSITION IS EXPECTED) GIVES A STORM TOTAL SNOWFALL OF 1-4

INCHES IN THE WATCH AREA. IF THE FORECAST STAYS ON TRACK... THE

WATCH MAY BE CHANGED TO AN ADVISORY OR WARNING BY THURSDAY MORNING.

-GIH 

 

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MotoWeatherman

MotoWeatherman

Posted
Posted

18z NAM says MBY turns to snow between 7pm -10pm.  Not likely to last long nor accumulate much but hey...

 

Date: 33 hour Eta valid 3Z FRI 18 JAN 13Station: 34.59,-83.93Latitude:   34.59Longitude: -83.93-------------------------------------------------------------------------------LEV PRES  HGHT  TEMP  DEWP  RH  DD   WETB DIR SPD THETA THE-V THE-W THE-E   W     mb     m     C     C    %   C     C  deg knt   K     K     K     K    g/kg-------------------------------------------------------------------------------  0 1000   167                                                                 SFC  954   549   2.3   1.0  92  1.2   1.7 353  11 279.1 279.9 277.2 291.0  4.32  2  950   582   1.8   0.8  93  1.0   1.4 358  13 279.1 279.8 277.1 290.8  4.27  3  900  1016  -0.4  -0.9  96  0.5  -0.6  14  33 281.1 281.8 277.7 292.2  3.98  4  850  1473  -1.4  -2.7  91  1.2  -2.0  25  50 284.6 285.3 279.1 295.1  3.69  5  800  1955  -1.9  -3.9  86  2.0  -2.7  12  46 289.2 289.8 281.1 299.5  3.58  6  750  2468  -2.1  -3.5  90  1.4  -2.7 358  40 294.3 295.0 283.7 305.9  3.94  7  700  3015  -4.2  -5.1  94  0.9  -4.6 347  31 297.8 298.5 284.9 309.1  3.74  8  650  3596  -7.8  -8.9  92  1.1  -8.2 360  26 300.1 300.7 285.1 309.3  3.00  9  600  4214 -11.3 -12.7  90  1.4 -11.8 351  37 303.1 303.5 285.5 310.6  2.40 10  550  4877 -14.5 -16.1  88  1.6 -15.0 340  46 306.9 307.2 286.5 313.2  1.98 11  500  5593 -19.3 -21.3  84  2.1 -19.8 338  42 309.6 309.8 286.8 314.1  1.39 12  450  6369 -24.5 -27.1  79  2.6 -24.9 339  44 312.5 312.7 287.3 315.6  0.93 13  400  7214 -31.5 -35.3  69  3.8 -32.0 350  43 314.1 314.1 287.3 315.7  0.47
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RaleighWx

RaleighWx

Posted
Posted

Allen, looking at these frames how many hours of actual snow? For RDU we see rain at 33, snow at 36, then ending by 39. So is this 3 or 6 hours of snow? 

Yep been saying that the whole time. THat is why we are not going to get crazy snow totals outside of the mountains. There could be a few hours of moderate to heavy snow, so a good 1 to maybe 4 inches generally seems the best bet.

 

I would say for RDU per the NAM our time frame for snow tomorrow is something 11pm-12zam to 3-4am. With some light snow maybe lingering till 5 or 6am.

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