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Feb 16th/17th/18th Winter Wx

burgertime

By burgertime,
in Southeastern States

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buckeyefan1

buckeyefan1

Posted
Posted

CAE.....   :)

 

.LONG TERM /MONDAY THROUGH FRIDAY/...
INCREASING CONFIDENCE FOR POSSIBLE WINTER WEATHER EARLY NEXT
WEEK...PARTICULARLY IN THE NORTHERN AND CENTRAL MIDLANDS.

MONDAY THROUGH WEDNESDAY NIGHT...MOISTURE WILL INCREASE ACROSS THE
AREA ON MONDAY AS DEVELOPING LOW PRESSURE OVER THE WESTERN GULF
MOVES NORTHEASTWARD TOWARD THE AREA. SURFACE HIGH PRESSURE OVER
THE OHIO VALLEY REGION WILL SHIFT EAST TOWARD THE MID-ATLANTIC
COAST ON MONDAY WITH AN ONSHORE FLOW PROMOTING ADDITIONAL MOISTURE
INTO THE AREA UNDER A WEDGE-LIKE SETUP. LIGHT PRECIPITATION MAY
BEGIN AS EARLY AS LATE MONDAY MORNING ALTHOUGH WILL HAVE TO
OVERCOME SIGNIFICANT DRY AIR IN PLACE. THE BEST MOISTURE REACHES
THE AREA MONDAY NIGHT INTO TUESDAY MORNING AS THE LOW NEARS THE
AREA AND ISENTROPIC LIFT INCREASES. STILL SOME UNCERTAINTY
REGARDING THE TRACK OF THE LOW. THE 12Z NAM TAKES THE CENTER OF
THE LOW ACROSS THE EASTERN CSRA WHILE THE 12Z GFS TRACK IS A
LITTLE FURTHER TO THE SOUTHEAST. THE GFS IS ALSO QUICKER TAKING
THE LOW OFF THE CAROLINA COAST THAN THE NAM. MODELS DIFFERENCES
ALSO EXIST REGARDING THE TIMING OF UPPER ENERGY REACHING THE AREA. THE
COLD AIR IN PLACE AHEAD OF THE SYSTEM SUPPORTS WINTER- TYPE
PRECIPITATION. THE BEST CHANCE FOR SNOW APPEARS TO BE IN THE
NORTHWESTERN MIDLANDS MONDAY EVENING. MODEL SOUNDINGS SUPPORT A
TRANSITION FROM SNOW AND/OR RAIN FOR MOST OF THE NORTHERN AND
CENTRAL MIDLANDS TO FREEZING RAIN MONDAY NIGHT WITH A WARM NOSE
DEVELOPING. MODELS HAVE BEEN TRENDING TOWARD HIGHER ICE
ACCUMULATIONS. FOR NOW HAVE FORECAST A TENTH OF AN INCH IN THE
CENTRAL MIDLANDS TO NEAR A QUARTER OF AN INCH IN THE NORTHERN
MIDLANDS ALTHOUGH THE NAM IS SHOWING MUCH HIGHER AMOUNTS. LOW
PRESSURE WILL SHIFT OFF THE COAST TUESDAY NIGHT WITH MOISTURE
EXITING THE REGION. STILL QUITE A BIT OF UNCERTAINTY IN THE
FORECAST ALTHOUGH CONFIDENCE IN WINTRY PRECIP AFFECTING AT LEAST PART
OF THE AREA IS INCREASING.

THURSDAY THROUGH SATURDAY...MEDIUM RANGE MODELS WHICH IN PREVIOUS
RUNS SHOWED A FAST MOVING CLIPPER TYPE SYSTEM CROSSING THE
FORECAST AREA ON THURSDAY...HAVE CHANGED TO GENERALLY DRY
CONDITIONS BUT STILL VERY COLD ON THURSDAY INTO FRIDAY.
HOWEVER...BOTH THE ECMWF AND GFS ARE HINTING AT YET ANOTHER STORM
SYSTEM DEVELOPING OVER THE MISSISSIPPI VALLEY AND MOVING INTO THE
FORECAST AREA BY LATE FRIDAY INTO SATURDAY WITH PLENTY OF COLD AIR
IN PLACE TO SUPPORT SOME TYPE OF WINTER PRECIPITATION. GIVEN THE
TIME LATE IN THE FORECAST AND WITH THE MODELS HAVING CHANGED QUITE
FREQUENTLY ON THEIR SOLUTIONS IN THE MEDIUM RANGE PERIOD AM
INCLINED TO REMAIN CONSERVATIVE WITH POPS. TEMPERATURES DURING
THIS PERIOD ARE EXPECTED TO BE 15-25 DEGREES BELOW NORMAL WITH
MORE ARCTIC AIR SETTLING OVER THE REGION.

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Lookout

Lookout

Posted
Posted

NAM looks like a raging ice storm for NE GA.

yeah i'm not liking it. I was hoping i could avoid the really serious icing here due to sleet but with the latest trends in the modeling, it's looking more and more like freezing rain. With such cold air over the carolinas, the nam actually starts dropping temps with time monday night instead of them slowly rising...again with caa thanks in part to a meso high like feature over nc.

 

One thing is clear this run matches up with other runs with later start time of precip. That does allow more warming during the day but wetbulbs are still in the upper 20s when precip starts..and per the nam it should be pretty heavy so i don't see any reason we don't drop to our wetbulbs.

 

I'm pretty amazed by one thing and that is how cold it is upstream over the carolinas, in particular north carolina while they stay in the 20s all day monday we rise well into the 30s if precip doesn't arrive until late in the day.

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packfan98

packfan98

Posted
Posted

Nam has a good track and colder 850's this run.  Looks like the low sets up from the FL panhandle to 75 miles east of Hatteras.  It's a bit strung out and not as wet NW of I-85 in the Carolina's this run after destroying TN.  I  imagine future runs will pick the precip back up for these areas.  I haven't looked at H5.

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superjames1992

superjames1992

Posted
Posted

Just a note: I-85 is all-snow.  RDU, etc. get a lot of sleet, as does the I-95 corridor.  Surface temps are cold throughout for many of us, all the way down into SC and GA.

 

Also, it's not over at hr 84, either, so there's still some more to come.  There's a moderate band of snow still rippin' in the foothills/western Piedmont with light snow elsewhere across much of NC/SC/GA/AL with a 998 mb LP off of Hateras.

 

Looks like 0.75" QPF of all-snow for GSO.  Checkout, please? :)

 

EDIT: Pack, I guess it must have been another level aside from 850 mb getting us over to sleet at hr 66 because it still looks good at that level.

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packbacker

packbacker

Posted
Posted

Yeah NAM running with 12z GFS idea

 

I am so confused, maybe it's because we haven't tracked anything this winter.  But, I was suspecting the NAM to come in much more amped, but it noticeably weaker and SE than it's 12z run.  I know the Euro struggles with NC dominated patterns but it's pretty darn good.  There is a huge difference between Euro/EPS/UK v/s GFS/GEFS/CMC/CMC-ENS/NAM, at really 48-60 hours is when the difference occurs. 

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packbacker

packbacker

Posted
Posted

Just a note: I-85 is all-snow.  RDU, etc. get a lot of sleet, as does the I-95 corridor.  Surface temps are cold throughout for many of us, all the way down into SC and GA.

 

Also, it's not over at hr 84, either, so there's still some more to come.  There's a moderate band of snow still rippin' in the foothills/western Piedmont with light snow elsewhere across much of NC/SC/GA/AL.

 

Looks like 0.75" QPF of all-snow for GSO.  Checkout, please? :)

 

You flip to sleet for a bit too, LOL, but yes for RDU it's about 2-3" of snow and 1.5" of sleet (0.5" QPF).  I have no idea what the heck is going to happen.

post-2311-0-30540600-1423947329_thumb.pn

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Wow

Wow

Posted
Posted

Just a note: I-85 is all-snow.  RDU, etc. get a lot of sleet, as does the I-95 corridor.  Surface temps are cold throughout for many of us, all the way down into SC and GA.

 

Also, it's not over at hr 84, either, so there's still some more to come.  There's a moderate band of snow still rippin' in the foothills/western Piedmont with light snow elsewhere across much of NC/SC/GA/AL with a 998 mb LP off of Hateras.

 

Looks like 0.75" QPF of all-snow for GSO.  Checkout, please? :)

 

You can see the evolution of the 2 wave to 1 wave scenario with the leading wave shooting west to east - that's what gets TN and W NC, then the axis rotates to a SW to NE direction as the baja low rushes in and you've got this elongated low setting up.

 

I think it'll continue to consolidate to a more pronounced singular low pressure like the UKMET and NAVGEM.. I like the trend here with the NAM but not there yet.  Shouldn't put much stock into this model anyway.

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packfan98

packfan98

Posted
Posted

I am so confused, maybe it's because we haven't tracked anything this winter.  But, I was suspecting the NAM to come in much more amped, but it noticeably weaker and SE than it's 12z run.  I know the Euro struggles with NC dominated patterns but it's pretty darn good.  There is a huge difference between Euro/EPS/UK v/s GFS/GEFS/CMC/CMC-ENS/NAM, at really 48-60 hours is when the difference occurs. 

 

I think you will see the NAM have some amped up solutions in future runs.  It was juiced in TN.  Once you get past 48hrs, the NAM is unpredictable.

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TropicalAnalystwx13

TropicalAnalystwx13

Posted
Posted

NWS ILM:

 

THINGS THEN BECOME VERY INTERESTING ON MONDAY. ARCTIC HIGH PRESSURE
WILL WEDGE DOWN INTO THE SOUTHEAST PRODUCING ANOTHER EXTREMELY COLD
AND DRY DAY ACROSS THE AREA. HIGHS MONDAY WILL AGAIN BE HELD TO
NEAR-RECORD LOW MAXIMUMS IN THE LOW AND MID 30S...BUT FORTUNATELY
WITH MUCH LIGHTER WINDS. THEREAFTER ALL EYES WILL TURN TO A SERIES
OF SHORTWAVES RACING EAST FROM THE SOUTHERN PLAINS WITHIN THE BROAD
EASTERN CONUS TROUGH. THE WILL SPAWN AREAS OF LOW PRESSURE WHICH
WILL MOVE ALONG THE BAROCLINIC GRADIENT SOUTH OF THE ARCTIC
AIRMASS...AND PRODUCE THE FIRST SIGNIFICANT WINTER WEATHER EVENT OF
THE SEASON. AS IS FREQUENTLY THE CASE WITH THESE EVENTS...P-TYPE
WILL BECOME THE MOST DIFFICULT CHALLENGE...AND NEARLY EVERY P-TYPE
IS EXPECTED MONDAY NIGHT. GUIDANCE STILL SHOWS CONSIDERABLE
DISAGREEMENT IN THEIR SOLUTIONS...AND HAVE PLACED MOST EMPHASIS ON
THE GFS FOR THE MONDAY NIGHT TIMEFRAME.

MOISTURE OVERRUNNING THE SURFACE WEDGE WILL BEGIN TO SATURATE THE
TROPOSPHERE MONDAY AFTN/EVE. GUIDANCE IS LIKELY OVERDOING THE SPEED
AT WHICH THIS SATURATION WILL OCCUR - AS THE ANTECEDENT AIRMASS IS
ABOUT AS COLD AND DRY AS CAN OCCUR HERE - AND WESTERLY FLOW IN THE
BROAD MID-LEVEL TROUGH RARELY LEADS TO A RAPIDLY-MOISTENING COLUMN.
ADDITIONALLY...FLOW ON THE 305K SURFACE MATCHES WELL WITH THE THE
DENDRITIC GROWTH ZONE LAYER (-10C TO -20C) AND THIS REMAINS NEARLY
"ISENTROPIC NEUTRAL" UNTIL MONDAY NIGHT. THEREFORE...THE SNOW BEING
FORECAST BY THE GUIDANCE MONDAY AFTN/EVE IS LIKELY OVERDONE...AND
HAVE SLOWED PRECIP ONSET CONSIDERABLY FROM GUIDANCE. THEREAFTER
THOUGH...ISENTROPIC LIFT BEGINS TO RAPIDLY INCREASE...ESPECIALLY
BETWEEN 280K AND 290K...WITH CROSS-ISOBAR WINDS INCREASING ALONG A
TIGHTENING SLOPE. THIS IS WHEN PRECIP SHOULD BREAK OUT ACROSS THE
ENTIRE CWA...AND WITH A SUB-FREEZING COLUMN INITIALLY...A LITTLE
LIGHT SNOW IS EXPECTED ACROSS MOST OF THE AREA MONDAY EVE/EARLY
MONDAY NIGHT...BUT NO SNOW ACCUMULATION EXPECTED...EXCEPT MAYBE LESS
THAN 1 INCH IN THE EXTREME NORTHERN ZONES.

WARM SW FLOW ATOP THE WEDGE QUICKLY DRIVES WARM NOSE DEVELOPMENT
MONDAY NIGHT...AND THUS PRECIP WILL TRANSITION TO R/ZR/IP CWA-WIDE.
AS LOW PRESSURE MOVES OFF THE COAST...COLD DRAINAGE SURFACE WINDS
WILL PERSIST...AND MONITORING WET-BULB TEMPERATURES WILL BE CRUCIAL
TO DETERMINING P-TYPE. GFS APPEARS TO HAVE A GOOD HANDLE ON
THIS...AND EXPECT SUB-FREEZING SURFACE AND WET-BULB TEMPS ACROSS THE
ENTIRE CWA FOR A FEW HOURS MONDAY NIGHT...BEFORE WARMING ABOVE
FREEZING FROM SE TO NW INTO TUESDAY MORNING. UNLIKE THE BIG ICE
STORM OF FEBRUARY, 2014 - SURFACE WINDS WILL BECOME MORE E/NE THAN
N/NE - CRUCIAL TO MAINTAINING SUB-FREEZING WET BULB TEMPS. EVEN
SO...A PROLONGED PERIOD OF ZR/IP IS BECOMING MORE LIKELY ACROSS THE
CWA...ESPECIALLY INLAND. STILL SOME UNCERTAINTY INTO HOW LONG IP
WILL REMAIN THE P-TYPE BEFORE CHANGING TO ZR...AND THIS WILL PLAY
DRASTICALLY INTO ACCUMULATION TOTALS...BUT WITH A WARM NOSE RISING
TO +6C AND A SUB-FREEZING LAYER BECOMING MORE AND MORE SHALLOW...ZR
IS EXPECTED TO BE THE PREDOMINANT P-TYPE AWAY FROM THE COAST...WITH
A LONG PERIOD OF IP BECOMING ZR WEST OF I-95. UNFORTUNATELY...THE
HEAVIEST PRECIP IS EXPECTED DURING ZR.

THIS LEADS TO A COMPLEX ACCUMULATION FORECAST - WHICH WILL LIKELY
UNDERGO SIGNIFICANT CHANGES AS WE GET CLOSER TO THE EVENT. WHERE ZR
IS PREDOMINANT...WARNING CRITERIA (0.25") IS DEFINITELY
POSSIBLE...WHILE MIXING WITH IP WOULD KEEP THE ICE ACCRETION TOTALS
DOWN ELSEWHERE. ONLY A TRACE OR A FEW HUNDREDTHS OF ICE IS EXPECTED
CLOSER TO THE COAST...ESPECIALLY IN SC.

OF COURSE...ONLY MINOR CHANGES IN TRACK AND INTENSITY OF THE SURFACE
LOW/WARM NOSE WILL HAVE A MAJOR IMPACT ON P-TYPE...SO THIS NEEDS TO
BE MONITORED CLOSELY. REGARDLESS OF EXACTLY HOW THE EVOLUTION OF
THIS SYSTEM PLAYS OUT...A SIGNIFICANT WINTER WEATHER EVENT IS ON TAP
FOR MONDAY NIGHT FOR AT LEAST PORTIONS OF THE CAROLINAS.

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jrips27

jrips27

Posted
Posted

FFC just pulled the trigger on a watch.

 

 

THE NATIONAL WEATHER SERVICE IN PEACHTREE CITY HAS ISSUED A
WINTER STORM WATCH...WHICH IS IN EFFECT FROM LATE SUNDAY NIGHT
THROUGH TUESDAY EVENING.

* LOCATIONS...PORTIONS OF NORTH GEORGIA...GENERALLY NORTH OF A
LINE FROM FRANKLIN TO STOCKBRIDGE TO WASHINGTON.

* HAZARD TYPES...A WINTRY MIX OF SNOW...SLEET AND FREEZING RAIN.

* ACCUMULATIONS...A TRACE OF SNOW AND/OR SLEET ON THE SOUTHERN
EDGE OF THE WATCH...WITH UP TO TWO INCHES OF SNOW AND SLEET ON
THE NORTH SIDE OF METRO ATLANTA. UP TO A QUARTER OF AN INCH OF
ICE IS POSSIBLE ACROSS THE WATCH AREA.

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packbacker

packbacker

Posted
Posted

I think you will see the NAM have some amped up solutions in future runs.  It was juiced in TN.  Once you get past 48hrs, the NAM is unpredictable.

 

 

The NAM looks super weird, especially compared to its last 2 runs.

 

For north-central/NW NC into S VA, it snows during the afternoon on Monday, shuts off and doesn't snow again until Tuesday evening.

 

That just seems odd. This has went from a Tuesday storm to a Monday-Wednesday storm.

 

Yeah, the only thing I took away from the NAM is that it focused bulk of winter precip for NC/VA on the coastal, not the over-running. 

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