December 1st is starting off with a bang, with more to follow on the 2nd!
Today, there are two different extremes occurring.
Currently there are winter storm warnings and advisories in the Texas panhandle into New Mexico, as a cold front is shoving itself through the area (see graphic). Snow and sleet is currently falling over Lubbock and other Texas panhandle areas, where a total of 1-3 inches of snow or sleet is expected to occur.
THE NATIONAL WEATHER SERVICE IN LUBBOCK HAS ISSUED A WINTER
WEATHER ADVISORY FOR SLEET AND LIGHT SNOW...WHICH IS IN EFFECT UNTIL
6 AM CST WEDNESDAY. THE WINTER STORM WARNING HAS BEEN CANCELLED. A
MIXTURE OF RAIN...SLEET AND SNOW IS LIKELY TODAY AND TONIGHT.
TOTAL ACCUMULATIONS OF 1 TO 3 INCHES OF SLEET AND SNOW ARE
EXPECTED BY AROUND OR SHORTLY DAYBREAK ON WEDNESDAY.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A WINTER WEATHER ADVISORY FOR SLEET MEANS PERIODS OF SLEET ARE
IMMINENT OR OCCURRING. SLEET MAY CAUSE DRIVING TO BECOME EXTREMELY
DANGEROUS...SO BE PREPARED TO USE CAUTION WHEN TRAVELING.
On the other side of things, southern Alabama, western Florida panhandle, and the very south eastern portions of Mississippi areas are experiencing a slight risk of severe weather! Along with this slight risk they have issued a 5% risk of tornadoes, which I find pretty odd for December 1st!
...GULF COAST AREA TONIGHT...
FEW CHANGES TO ONGOING FORECAST SCENARIO...WITH SLIGHT RISK CALIBER
TORNADO/DAMAGING WIND PROBABILITIES MAINTAINED FOR TONIGHT FOR GULF
COASTAL PORTIONS OF LA/MS/AL AND FL PANHANDLE. ONGOING CONVECTIVE
CLUSTER OVER THE CENTRAL GULF OF MEXICO SHOULD CONTINUE TO REINFORCE
A BAROCLINIC ZONE THAT ROUGHLY BISECTS THE GULF PER OCEANIC
OBSERVATIONS/VISIBLE SATELLITE...WITH CONTINUED CYCLOGENESIS NOTED
IN THE WAKE OF THESE STORMS OVER THE WESTERN GULF /PER BUOYS 42020
AND 42002/. THIS SCENARIO SUGGESTS THE APPROACH OF A WARM/MOIST
MARINE AIRMASS AND CORRESPONDING SURFACE BASED SEVERE POTENTIAL WILL
BE TEMPORALLY/SPATIALLY CONFINED TO SOUTHERN LA THIS EVENING...AND
OTHERWISE THE LATTER SEVERAL HOURS OF THE PERIOD EARLY WEDNESDAY
ALONG THE MS/AL/FL PANHANDLE COAST. GIVEN LATTER PERIOD SURFACE
BASED DESTABILIZATION INLAND ATTENDANT TO AN ENCROACHING MARINE
AIRMASS...INCREASINGLY STRONG DEEP LAYER SHEAR/LOW LEVEL SRH WOULD
SUPPORT A RISK FOR DAMAGING WINDS/TORNADOES.
Tomorrow will bring some even more interesting weather as the same system creating severe weather in the Gulf will move east and slightly northward, as well as intensify! The area of risk becomes larger, as well as a higher risk. There will be just enough instability for some convective storms, with values of around 750 j/kg. When that cold front punches through and lifts that warm air up, some storms will definitely form. Max cape on the NAM run appears to be around 1 P.M. EST. With -4/5 lift index, and helicity values ranging from 200 to well over 500 in some areas, it looks like there could be some severe storm development! Little interesting fact about helicity…
Helicity - A property of a moving fluid which represents the potential for helical flow (i.e. flow which follows the pattern of a corkscrew) to evolve. Helicity is proportional to the strength of the flow, the amount of vertical wind shear, and the amount of turning in the flow (i.e. vorticity). Atmospheric helicity is computed from the vertical wind profile in the lower part of the atmosphere (usually from the surface up to 3 km), and is measured relative to storm motion. Higher values of helicity (generally, around 150 m2/s2 or more) favor the development of mid-level rotation (i.e. mesocyclones). Extreme values can exceed 600 m2/s2.
(courtesy of spotterguides.us)
Another factor that will help severe storms in a semi-decent temperature inversion that will hinder the development of storms, only allowing storms that are strong enough to break through to develop. Here are a couple of graphics, and the SPC discussion.
...NORTHEAST GULF/SOUTHEAST STATES TO CAROLINAS/SOUTHEAST VA...
AN APPRECIABLE/LONG DURATION SEVERE POTENTIAL STILL APPEARS LIKELY
ACROSS THE REGION WEDNESDAY/WEDNESDAY NIGHT...WITH A FEW
STRONG/DAMAGING EVENTS POSSIBLE. SHOWERS/TSTMS WILL LIKELY BE
ONGOING AT THE BEGINNING OF THE PERIOD...MOST LIKELY ACROSS AL/FL
PANHANDLE IN GENERAL ASSOCIATION WITH A LEAD MID LEVEL IMPULSE/WEAK
SURFACE LOW. AS THE PARENT UPPER SYSTEM ACCELERATES NORTHEASTWARD
AND TAKES ON A MORE NEGATIVE TILT...A MOIST/POTENTIALLY UNSTABLE
AIRMASS WILL DEVELOP NORTH-NORTHEASTWARD DURING THE DAY...DISPLACING
A COOL/STABLE CONTINENTAL AIRMASS/CURRENT HIGH PRESSURE WEDGE ACROSS
THE NORTHEAST GULF COAST STATES TO CAROLINAS VICINITY. WHILE WEAK
LAPSE RATES AND WIDESPREAD CLOUD COVER MAY TEND TO HINDER STRONGER
SURFACE BASED DESTABILIZATION...A STEADY INFLUX OF 60S F SURFACE
DEWPOINTS/DIURNAL HEATING SHOULD BE SUFFICIENT FOR AN
ONGOING/DIURNALLY INCREASING AND WELL-SUSTAINED SEVERE THREAT
ALONG/AHEAD OF THE SYNOPTIC COLD FRONT AND/OR EXISTING CONVECTIVE
LINE. STRENGTHENING DEEP LAYER WIND FIELDS WITH ELONGATED LOW LEVEL
HODOGRAPHS /GENERALLY 200 TO 500 MS PER S2 0-1 KM SRH/ WILL BE
FAVORABLE FOR A MIXED MODE OF SUPERCELLS/LEWPS...WITH ASSOCIATED
DAMAGING WIND/TORNADO POTENTIAL...A FEW OF WHICH MAY BE STRONG
ESPECIALLY WITH ANY PRE-CONVECTIVE LINE/QUASI-DISCRETE CELLS ACROSS
SOUTHERN GA/NORTHERN HALF OF FL TO THE COASTAL CAROLINAS.
This same cold front will bring some heavy raid to the area as well, and at one point there was a small possibility of snow… but the National Weather Service has removed that part of the forecast. Stay warm and dry!
