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Potential Big Dog Snow Event February 15th


Stovepipe

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WPC Disco on their track reasoning from earlier. This was prior to the 00z models coming in tonight. The I-95 track is usually good for us.

 

 

 

ANTECEDENT COLD AIR -- RECORD
COLD -- SHOULD HAVE AT LEAST SOME AFFECT IN LIMITING A FAR WESTERN
TRACK WEST OF THE APPALACHIANS AS COLD AIR IS USUALLY SLOW TO EXIT
-- SLOWER THAN WHAT THE MODELS PREDICT. IN ADDITION, EVOLUTION OF
NORTHERN STREAM THROUGH THE GREAT LAKES AND AN UPPER LOW IN CANADA
ALL PLAY A PART IN HOW MUCH TO DIG THE SHORTWAVE INTO THE
SOUTHEAST AND WHERE IT MAY CLOSE OFF. ENSEMBLES HAVE GONE FROM
NEARLY UNANIMOUS AGREEMENT ON A CLOSE-IN COASTAL TRACK TO A SPLIT
-- THE ECMWF ENSEMBLES MOSTLY INLAND AND THE GEFS/CANADIAN
ENSEMBLES MOSTLY OFFSHORE. OPTED TO TAKE THE LOW BASICALLY ALONG
I-95 FROM SC TO RICHMOND THEN PHILLY AND INTO CENTRAL NEW ENGLAND.
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EPS Control is almost a mirror image of the Op and the EPS means are 2-5 inches generally south to north across almost the entire Valley. North of 40 and Cumberland Gap west have the general 4-5 inch average that slowly tiers down to 3.5, 3, 2.5 etc. The 2 inch line is basically along the northern edge of the southernmost row of counties across nearly all of Tennessee. All in all a pretty healthy average for almost our entire region. The entire state has at least 1.5 average on the means. Northern Alabama and Mississippi have 1-1.5 average. So does North Georgia with their numbers rising as you head into NE Georgia.

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Morristown Disc. is very detailed and interesting.

 

 

.LONG TERM (THURSDAY THROUGH TUESDAY)...

VERY TRICKY FORECAST IN THE EXTENDED PERIOD...AS ATTENTION TURNSTO THE POSSIBILITY FOR ANOTHER WINTER STORM BEGINNING LATE SUNDAYNIGHT THROUGH MONDAY NIGHT. THE FORECAST FOR THIS PERIOD IS STILLHIGHLY UNCERTAIN...GIVEN THE MODEL DIFFERENCES ON TIMING...THEVERTICAL TEMPERATURE PROFILE...AND PRECIPITATION TYPE AND DURATIONFOR THIS EVENT.MOST MODELS GENERALLY SHOW THE ONSET OF PRECIPITATION BEING ALLSNOW...FOLLOWED BY A WARM-UP DURING THE DAY ON MONDAY /PRESIDENT`SDAY/...CHANGING SNOW TO MIX OF SNOW/RAIN...FOLLOWED BY A CHANGE BACKTO ALL SNOW LATE IN THE EVENT MONDAY NIGHT. THE ECMWF SHOWS A WEAKERSURFACE AND 850 MB LOW MUCH FURTHER NORTH /ALMOST DIRECTLY OVER THEI-40 CORRIDOR/...WITH PRECIPITATION BEGINNING MUCH EARLIER...JUSTAFTER MIDNIGHT SUNDAY NIGHT. THIS WOULD ALLOW PRECIPITATION AT THEONSET TO POTENTIALLY BEGIN AS MODERATE TO LOCALLY HEAVYSNOW...BEFORE CHANGING OVER TO A FREEZING RAIN/SNOW/RAIN MIX DURINGTHE AFTERNOON OVER MUCH OF THE VALLEY...AND EVENTUALLY LIGHT SNOW ONTHE BACK SIDE MONDAY NIGHT.THE GFS SHOWS PRECIPITATION BEGINNING SLIGHTLY LATER ON MONDAYMORNING...BEGINNING AS SNOW AND THEN POSSIBLY MIXING WITHRAIN...SLEET OR FREEZING RAIN DURING THE AFTERNOON...BEFORETRANSITIONING OVER ALL MODERATE TO HEAVY SNOW MONDAY NIGHT AS THE850 MB LOW TRACKS INTO THE NORTH GEORGIA MOUNTAINS. THIS SOLUTIONWOULD PLACE PORTIONS OF THE EASTERN TENNESSEE VALLEY AND THE EASTTENNESSEE AND NORTH CAROLINA MOUNTAINS UNDERNEATH THE TROWELREGION...AND SUPPORT A WIDESPREAD MODERATE TO HEAVY SNOW MONDAYNIGHT...BEFORE TAPERING OFF TUESDAY MORNING. AN EXAMINATION THE VERYSTRONG Q-VECTOR CONVERGENCE DIRECTLY OVER THE GREAT SMOKY MOUNTAINSAT 06Z THURSDAY CONFIRMS THIS.GIVEN THE DIFFERENCES OUTLINED ABOVE...HAVE NOT GOTTEN TOO SPECIFICWITH PRECIPITATION TYPE OR AMOUNTS GIVEN THAT THIS IS A LOWCONFIDENCE FORECAST. HOWEVER...CONFIDENCE IS REASONABLY HIGH THATMOST/ALL OF THE REGION WILL EXPERIENCE SNOW AND POTENTIALLY OTHERFORMS OF WINTRY PRECIPITATION SOMETIME DURING THE MONDAY AND MONDAYNIGHT TIMEFRAME. ADDITIONALLY...HIGHER CONFIDENCE EXISTS REGARDINGTHE POSSIBILITY FOR A SIGNIFICANT SNOWFALL ALONG THE EAST TENNESSEEAND NORTH CAROLINA MOUNTAINS...AND PERHAPS PORTIONS OF FAR NORTHEASTTENNESSEE AND SOUTHWEST VIRGINIA. HOWEVER...A MUCH LOWER CONFIDENCEEXISTS REGARDING SPECIFIC DETAILS FOR SNOWFALL AMOUNTS ANDPRECIPITATION TIMING/TYPE FOR MUCH OF THE VALLEY /INCLUDING THEKNOXVILLE AND CHATTANOOGA METRO AREAS/...AND THE CUMBERLAND PLATEAU.PLEASE STAY WEATHER AWARE THIS WEEKEND...AND MONITOR THE LATESTFORECAST INFORMATION FROM THE NATIONAL WEATHER SERVICE REGARDINGTHIS STORM SYSTEM...ESPECAILLY IF YOU HAVE TRAVEL PLANS!IN WAKE OF THIS SYSTEM...MODELS SHOW A RETURN TO SOUTHERLY FLOW ASAN UPPER-LEVEL HIGH PRESSURE RIDGE LOOKS TO BUILD INTO THE TENNESSEEVALLEY FOR THE LATER HALF OF THE WEEK. THIS WILL ALLOW FOR MORESUNSHINE AND HIGH TEMPERATURE TO GRADUALLY REBOUND INTO THE 50S ANDPERHAPS WELL INTO THE 60S TOWARD THE END OF THE WORK WEEK.
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Personally I'm very skeptical of the snow to rain to snow scenario. If the low track stays closer to the coast, I doubt we change back and forth. If we start as snow, we should remain snow. It's pretty difficult dynamically to get that changeover to rain to happen with the low track shown. Of course if the low drifts too far NW, that theory is out the window. It is possible that the daytime nature of the event will hamper accumulation, but I don't think it will actually change the p type.

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0z EPS:  Control is similar to op but has beefier totals for plateau and upper Cumberland.  The mean was a tad light but covers the entire region in 2 to 4 south to north, eastern valley on the lighter side of that.  The low clusters are in line with the WPC track although there are a few cutters in there that track up through TN.

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Thanks Stove for the update on the para and the ensembles looks like a decent shot. Maybe it will work out for all of us. Side note: This little clipper tonight and tomorrow kinda snuck up on us huh? The 4K and 12k NAM has been consistent with it just like the vort last night. Point being, the GFS hasn't been too good even in the very short term. Maybe this system will also work out for us. I think the ensembles are definitely the way to go right now.

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Like every event seems to be in this area.....seems as if temps are going to be an issue.  Again.  But...we have a storm to track, and it's still a few days out.  A lot can change.  Staying optimisitc!!!! 

 

Oh I'm very optimistic.  It's going to be 15 degrees Saturday night, I'm hopeful the surface temps are favorable come storm time.

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Personally I'm very skeptical of the snow to rain to snow scenario. If the low track stays closer to the coast, I doubt we change back and forth. If we start as snow, we should remain snow. It's pretty difficult dynamically to get that changeover to rain to happen with the low track shown. Of course if the low drifts too far NW, that theory is out the window. It is possible that the daytime nature of the event will hamper accumulation, but I don't think it will actually change the p type.

Me too, I believe you are right.  We are talking about precip starting before daybreak and potentially putting down a good coating before daybreak once we have some snow on the ground it will be harder to switch back and forth too much, unless as you mention the low placement is further north.  Also if it is stronger while in MS and AL then southerly flow would be stronger and could hurt for the southern valley.

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Last night's runs are as good as we're ever likely to see. The GFS has handled this differently than the other models the entire time. So who knows if it's correct. Either way we've not got much direction to go but down after those 00z monsters. And I do sleep but only 3 or 4 hours a night. Also, the dog never catches the deer but chases them all winter at night. During summer he has a deal where they eat every melon I try to grow.

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