January Pattern and Storm Discussion II

[tarheelwx]

You'd have to be right.   I'm shocked at how low the high temperatures are progged to be on Friday with a slp projected to be north of us.  I guess we all know how hard it is to get that lower level cold pushed out once it gets wedged in. Looks like it could be one of those days where we dont get above freezing here in the Triad.  

Yes.  And some models are giving the triad close to .50 qpf.  So, there is reasonable chance that it could be significant.  Cold ground temps this time around as well.

TW

[Poimen]

You'd have to be right.   I'm shocked at how low the high temperatures are progged to be on Friday with a slp projected to be north of us.  I guess we all know how hard it is to get that lower level cold pushed out once it gets wedged in. Looks like it could be one of those days where we dont get above freezing here in the Triad.  

I think the reason for that is the NWS is basing the forecast on a LP track further south than the models are indicating…along the NC/SC border or even across SC.

[tnweathernut]

I have noticed when following clippers there is usually a correction north from 4-5 days in.  This would be detrimental to snow/ice chances on a major scale, but wouldn't necessarily rule it out.  Trends in the coming 24 hours will be crucial.

[Poimen]

I have noticed when following clippers there is usually a correction north from 4-5 days in.  This would be detrimental to snow/ice chances on a major scale, but wouldn't necessarily rule it out.  Trends in the coming 24 hours will be crucial.

I'm not sure this is really a "clipper." I mean, best I can tell the LP in question is coming from CO and is in the southern stream.

[Scooter]

I'm excited to be tracking another storm this year. But I have a question, if it is coming across the mountains will the moisture dry up before it gets to the CAD areas. Or will this not be the case with this system. I've read in the past on here where Miller B's have a hard time getting moisture east of the mountains.

[HKY_WX]

I'm excited to be tracking another storm this year. But I have a question, if it is coming across the mountains will the moisture dry up before it gets to the CAD areas. Or will this not be the case with this system. I've read in the past on here where Miller B's have a hard time getting moisture east of the mountains.

It's not an ideal setup at all, but i've seen us get snow from these clipper/coastal genesis storms many times. But to be honest, they are usually in great winters during very cold -AO periods. This could be a great sign for the rest of winter IMO. I've been tooting that horn for a month that -AO Oct/Nov/Dec combo generally bods well for Jan/Feb.

[eastkywx]

Jackson, KY NWS obviously having a hard time figuring out what to do with this weekends storm as well:

 

LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)ISSUED AT 415 AM EST TUE JAN 22 2013A COMPLEX WINTRY PRECIPITATION EVENT REMAINS THE BIGGEST CONCERNDURING THE PERIOD FROM THURSDAY NIGHT INTO FRIDAY...LINGERING INTOEARLY ON SATURDAY.FOLLOWING A REINFORCING SHOT OF COLD AIR EARLY IN THE PERIOD...AWINTER STORM SYSTEM IS EXPECTED TO BEGIN TO TAKE SHAPE ACROSS THE OHAND TN VALLEY REGIONS. IN FACT...THE KEY SHORTWAVE FOR THIS SYSTEM ISSTILL OVER THE EASTERN PACIFIC AND HAS YET TO REACH THE WESTERN CONUS.AT THE MID AND UPPER LEVELS...INITIALLY A SHORTWAVE IS EXPECTED TOPASS BY TO THE NORTHEAST OF THE REGION EARLY IN THE PERIOD THROUGH ATROUGH OVER EASTERN CANADA AND THE EASTERN SEABOARD. AT THATPOINT...RIDING IS EXPECTED TO EXTEND FROM NORTHERN MEXICO NORTH INTOTHE WESTERN PLAINS. ABOUT THAT TIME...A SHORTWAVE TROUGH WILL BEMOVING ACROSS THE PACIFIC NORTHWEST WITH ANOTHER TO ITS SOUTHWEST.THE TROUGH MOVING ACROSS THE PACIFIC NORTHWEST NEAR THE US/CANADIANBORDER WILL TRACK TOWARD THE WESTERN GREAT LAKES BY LATE THU NIGHTWITH THE SHORTWAVE FURTHER TO THE SOUTHWEST POSSIBLY STARING TO COMEINTO PHASE WITH THIS MORE NORTHERN SYSTEM. THE LAST COUPLE OF ECMWFRUNS ARE MORE PRONOUNCED WITH THIS MORE SOUTHERN SHORTWAVE TO TRACKACROSS THE OH VALLEY ON FRI COMPARED TO GFS RUNS. THERE IS RUN TO RUNVARIABILITY AS THE 0Z ECMWF IS A BIT WARMER THAN THE PREVIOUS ONE.THE 12Z RUN FROM MON WOULD POINT TOWARD A SNOW CHANCE ACROSS THEENTIRE AREA WITH SOME THREAT OF MIX IN THE SOUTH. THE 0Z ECMWF RUNBRINGS THE THREAT OF A MIX FURTHER TO THE NORTH WITH SNOW OR ALMOSTALL SNOW NEAR THE I 64 CORRIDOR AND NORTH. THE NAM IS WARMER THAN THEOTHER MODELS WITH THE COLD SHOT LEADING UP TO THIS EVENT ON WED NIGHTINTO THU AND HAS BEEN DISCOUNTED ALTOGETHER. THE LATEST GFS IS ALSOPROBABLY TOO WARM...AT LEAST WITH ITS MEX MOS NUMBERS CONSIDERING HOWCOLD THE AIRMASS ARRIVING ON WED NIGHT INTO THU.

 

AT THE PRESENT TIME...SINCE A COLD AIRMASS WILL ALREADY BE INPLACE AT THE LOWEST LEVELS...THE MOST LIKELY SCENARIO FROM NEAR THEMTN PARKWAY AND SOUTH...PRECIPITATION WOULD LIKELY BEGIN ASSNOW...THEN EVOLVE INTO A MIX OF SNOW AND SLEET...BEFORE MIXING IN ATLEAST THE MORE SOUTHERN LOCATIONS WITH FREEZING RAIN AND IN THESEAREAS POSSIBLY GOING TO ALL RAIN. LOCATIONS CLOSER TO THE MTN PARKWAYAND POSSIBLY THE WV BORDER MAY EXPERIENCE MORE FROZEN OR FREEZINGPRECIP WITH LOCATIONS NEAR THE TN AND VA BORDERS...HAVING THE HIGHESTCHANCE OF GOING TO ALL RAIN. EXACTLY WHERE THIS SETS UP VARIES FROMMODEL TO MODEL AND RUN TO RUN. THE SHORTWAVE TROUGHS THAT WILL LEADTO THE EVOLUTION OF THIS SYSTEM HAVE YET TO REACH THE PACIFIC COASTAND WILL NOT DO SO UNTIL WED. AS WE MOVE INTO MIDWEEK...MODELS WILLLIKELY COME INTO BETTER AGREEMENT ON THE TIMING...AMOUNT OF MOISTUREAND THERMAL PROFILE WITH THIS SYSTEM. HOWEVER...THE THREAT OF A HIGHIMPACT WINTRY PRECIP EVENT EXISTS SOMEWHERE IN THE OH AND TN VALLEYREGION FROM THU NIGHT INTO FRI NIGHT. THE HWO WILL BE MODIFIED A BITTO HIGHLIGHT THE CURRENT EXPECTED TIMING AND THREATS.

[eyewall]

If the CAD is really able to establish itself this could end up a Miller B scenario as energy transfers across the wedge and a new low develops. Obviously if that happens we get a mixed bag with some spots approaching winter storm criteria for a variety of p-types.

[NCStateMMY]

For those of you who haven't experienced a minor event with cold ground - it's a fun experience. Almost two years ago in Nashville - high temp of 23 when snow moved in. It immediately stuck to everything. Roads did melt for about 15 minutes but then turned into sheets of ice/snow. This started at 3:30 pm. Interstate traffic was gridlocked until midnight. All for 2 inches of snow.

 

That is the exact same thing that happened in Raleigh on 1/19/2005 during the infamous "Half-inch City Shutdown".

[Buddy1987]

If the CAD is really able to establish itself this could end up a Miller B scenario as energy transfers across the wedge and a new low develops. Obviously if that happens we get a mixed bag with some spots approaching winter storm criteria for a variety of p-types.

Which essentially is what Blacksburg is alluding to as well if you read there AFD. I believe personally the CAD will be stronger as we progress the next 48 hours as most know here they always tend to under do it.

[eyewall]

Which essentially is what Blacksburg is alluding to as well if you read there AFD. I believe personally the CAD will be stronger as we progress the next 48 hours as most know here they always tend to under do it.

 

I will be closely monitoring the strength of the parent high and how progressive it will be.

[MotoWeatherman]

6z GFS has a nice light freezing rain/sleet event across much of north GA for at least the first half of Friday.  Here is the sounding for MBY at 1pm Friday which shows temps in the 20's. 

Date: 3.5 day AVN valid 18Z FRI 25 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   191                                                                 SFC  964   479  -2.7  -4.7  86  2.0  -3.4 163   4 273.3 273.8 271.7 281.0  2.80  2  950   598  -4.0  -5.5  89  1.5  -4.6 176   5 273.1 273.5 271.4 280.4  2.66  3  900  1026  -0.4  -0.5  99  0.1  -0.5 223  25 281.1 281.7 277.9 292.4  4.08  4  850  1488   3.9   3.9 100  0.0   3.9 239  46 290.2 291.3 284.2 307.2  5.95  5  800  1982   3.5   3.5 100  0.0   3.5 253  53 294.9 296.0 286.3 312.8  6.16  6  750  2504   1.0   0.9  99  0.1   1.0 262  55 297.7 298.7 286.7 313.9  5.46  7  700  3057  -1.9  -2.1  99  0.2  -2.0 268  55 300.3 301.2 286.9 314.4  4.69  8  650  3643  -5.4  -6.2  95  0.7  -5.8 267  55 302.8 303.5 286.8 314.2  3.71  9  600  4268  -8.1 -10.5  83  2.4  -9.0 272  58 306.7 307.3 287.3 315.7  2.86 10  550  4942  -9.7 -12.2  82  2.4 -10.6 276  65 312.6 313.1 289.2 321.4  2.74 11  500  5673 -13.6 -16.7  78  3.1 -14.6 275  72 316.5 316.9 289.8 323.4  2.08 12  450  6468 -17.6 -21.7  71  4.0 -18.7 268  80 321.1 321.4 290.6 326.3  1.50

[GaWx]

If one were to read FFC's current discussion and forecasts, he/she would have no idea that there is a ZR threat for Friday. There is zero mention of even a chance for ZR on Friday in any of N GA...only rain showers. Moreover, the Friday lows for ATL and Marietta are forecasted to get down only to 40 F vs. the 6Z GFS' upper 20's. Gainseville is fcasted to get down only to the mid 30's vs. the 6Z's 25 F. Could the 6Z GFS be quite a bit too cold? Considering the GFS cold bias, of course it can. I'm often talking about the GFS being too cold. However, this situation is different from most as it is trending colder and, more importantly, has upper 20's with precip. and wedging. A wedge accompanied by precip. in N GA is one of the few situations for which the GFS actually tends to be too warm more often than too cold. By the way, the crucial thing is that the GFS is showing fresh cold air with TD's dropping to the lower teens Thu. night in Atlanta and down to only 9 F at Gainseville just ahead of the precip. Is the GFS overdoing the dryness? Perhaps, but it usually doesn't in these situations.

By the way, I don't recall there even being a single GFS run in at least two years showing Marietta getting ZR with the temp. down as low as 29F initially. Winter wx enthusiasts are in for a fun few days watching this potential winter event evolve.

[MotoWeatherman]

Backing it up a bit to the 1am Friday sounding shows solid below freezing wetbulb column before the precip arrives.  So IMHO that could equal a brief start as sleet/snow before the mid levels warm to change all precip to sleet/freezing rain. 

 

Something to watch for sure.

 

Date: 3 day AVN valid 6Z FRI 25 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   238                                                                 SFC  970   479  -4.5  -8.8  72  4.4  -5.8 102   7 271.1 271.4 269.1 276.6  2.02  2  950   642  -5.0 -11.4  61  6.4  -6.8 104  12 272.1 272.4 269.2 276.8  1.68  3  900  1066  -4.8 -10.8  63  5.9  -6.6 137  13 276.5 276.8 272.2 281.8  1.87  4  850  1519  -0.8 -13.3  38 12.5  -4.8 226  16 285.3 285.6 276.7 290.0  1.61  5  800  2005   0.6 -11.4  40 11.9  -3.6 264  25 291.8 292.1 280.4 297.8  2.00  6  750  2523   0.7 -17.1  25 17.9  -4.9 268  29 297.4 297.6 282.0 301.6  1.33  7  700  3076   0.1 -26.9  11 27.0  -6.9 266  34 302.6 302.7 283.2 304.6  0.60  8  650  3666  -2.4 -34.7   6 32.3  -9.3 266  38 306.2 306.3 284.3 307.3  0.31  9  600  4297  -5.7 -38.8   5 33.1 -11.9 270  42 309.5 309.5 285.4 310.3  0.22 10  550  4974  -9.1 -44.9   4 35.8 -14.7 273  45 313.3 313.3 286.6 313.8  0.13 11  500  5705 -12.7 -50.5   3 37.8 -17.6 278  50 317.6 317.6 288.1 317.9  0.07 12  450  6503 -16.5 -40.8  10 24.3 -20.3 282  54 322.5 322.5 289.8 323.4  0.24

[Brick Tamland]

It doesn't appear to be a lot of precip involved with this system, but that can always change. As others have said, we don't need a lot to cause havoc on the roads here. In fact, these systems that bring a mix bag often create a lot of trouble on the road. It's not good when you have ice on top of snow or vice versa.

[franklin NCwx]

If one were to read FFC's current discussion and forecasts, he/she would have no idea that there is a ZR threat for Friday. There is zero mention of even a chance for ZR on Friday in any of N GA...only rain showers. Moreover, the Friday lows for ATL and Marietta are forecasted to get down only to 40 F vs. the 6Z GFS' upper 20's. Gainseville is fcasted to get down only to the mid 30's vs. the 6Z's 25 F. Could the 6Z GFS be quite a bit too cold? Considering the GFS cold bias, of course it can. I'm often talking about the GFS being too cold. However, this situation is different from most as it is trending colder and, more importantly, has upper 20's with precip. and wedging. A wedge accompanied by precip. in N GA is one of the few situations for which the GFS actually tends to be too warm more often than too cold. By the way, the crucial thing is that the GFS is showing fresh cold air with TD's dropping to the lower teens Thu. night in Atlanta and down to only 9 F at Gainseville just ahead of the precip. Is the GFS overdoing the dryness? Perhaps, but it usually doesn't in these situations.

By the way, I don't recall there even being a single GFS run in at least two years showing Marietta getting ZR with the temp. down as low as 29F initially. Winter wx enthusiasts are in for a fun few days watching this potential winter event evolve.

Larry, from what I can see the euro is even colder than the gfs.

[Cold Rain]

66 hour 12Z NAM is colder than the 78 hour 0Z NAM, which means absolutely nothing at this point. However, it is the only model running right now, so there you go.

[Cold Rain]

At 72, it's colder and farther south with the low and the high is farther west.

[NavarreDon]

At 72, it's colder and farther south with the low and the high is farther west.

 

[Cold Rain]

Thanks Don! Of course the next two frames keep the north track and kill the wedge. But, it's the long range NAM, so the reasonable thing to do is throw it out.

[MotoWeatherman]

Thanks Don! Of course the next two frames keep the north track and kill the wedge. But, it's the long range NAM, so the reasonable thing to do is throw it out.

 

Remember how far north the NAM was with our last storm at this time frame?

[Cold Rain]

Remember how far north the NAM was with our last storm at this time frame?

Lol! Yeah, good point!

[superjames1992]

I think it's about time to create a dedicated thread for this storm threat.  Is a Cold Rain Guarantee in order?

[CLTwx]

Panovich is honking?

 

"We really need to watch this Friday storm could be a icy mess combined with a little snow. lh6.googleusercontent.com/-ZtqeiQXRKd4/U"

[NGaWxNerd]

I think it's about time to create a dedicated thread for this storm threat.  Is a Cold Rain Guarantee in order?

Yes, please. Before the kid gets out of class and dooms us.

[GaWx]

Larry, from what I can see the euro is even colder than the gfs.

I see why you're saying the Euro is colder than the GFS if you're basing that on 850's. At 2 meters, I'm seeing the GFS being colder as of now verbatim. Regardless, the Euro tends to have a pretty strong warm bias at 2 meters (in our area at least) when there is steady precip. falling in many wintertime situations. So, I'm taking the Euro's 2 meter temp.'s with a big grain.

[burgertime]

Panovich is honking?

 

"We really need to watch this Friday storm could be a icy mess combined with a little snow. lh6.googleusercontent.com/-ZtqeiQXRKd4/U"

 

Interesting, I do agree that the NAM is inching south with each run. I won't get excited until 00z tonight...who am I kidding? If the 12z shows the same trend and looks better it's time to get tracking.

[FallsLake]

Thanks Don! Of course the next two frames keep the north track and kill the wedge. But, it's the long range NAM, so the reasonable thing to do is throw it out.

I thought they looked real close for us (Central NC). 2M temps are below freezing at 78 (wityh precip falling) and then just above at 84. I think this was another good trend. Also going on what RAH sayed last night low level cold air will have a harder time being pushed out from what current models indicate. **I personally think we have a good shot at wintery precip, but the big question is going to be type and amounts. 

[franklin NCwx]

I see why you're saying the Euro is colder than the GFS if you're basing that on 850's. At 2 meters, I'm seeing the GFS being colder as of now verbatim. Regardless, the Euro tends to have a pretty strong warm bias at 2 meters (in our area at least) when there is steady precip. falling in many wintertime situations. So, I'm taking the Euro's 2 meter temp.'s with a big grain.

Yes, I am basing that off 850 temps. The euro is more of a snow/sleet deal in western NC. The surface temps are a little warmer than the gfs. But with less WAA in the mid levels the surface temps on the euro should be colder, compared to the gfs.

[tnweathernut]

Positively tilted troughs will not advect as much warm air into the upper levels so we have that going for us.  (you guys in the CAD areas are looking better and better)