Friday, April 23, 2010

easy choice for a title......HIGH RISK!!

Well SPC has pulled out the high risk with the 6z outlook (pretty large area for the first outlook of the day). For the past week it seems weather geeks and forecasters have been talking about the potential for severe weather outbreak in the south and now were in the morning of getting ready for a possible historic tornado outbreak in parts of AR/TN/LA/MS/AL.



Today was somewhat of a bust givn the 15% hatched tornado probs put out but tomorrow has alot higher confidence but there still are a few things that could play havoc on this setup that I have been looking at tonight.

1. The current convection in eastern TX working its way eastward could stabilize the warm sector and not allow for good enough heating later in the day limiting the risk of potential long track, violent tornadoes.

2. The track of the surface low and how quickly it deepens. A further north and west track would lessen the amount of forcing in the warm sector early on which would mean not as much junk convection to hamper heating.

3. The mid level dry punch, I think this is going to be the key player on what plays out tomorrow. If this can happen during the day tomorrow and allow surface temps to really warm up, then some high amounts of instability coupled with insane amounts of shear (both bulk shear and low level shear) is a deadly combination for cyclic supercells tomorrow in the warm sector producing alot of tornadoes, potentially violent ones at that.

forecast offices have been comparing past outbreaks in the late 90's to this setup and writing amazing AFD's that were just through the roof good on the potential this thing had and letting people know ahead of time. If things play out right tomorrow (or wrong for that matter) then we could be looking at a major tornado outbreak across the south.

here is the text from the new day 1 from SPC....I will probably be doing updated throughout the day with radar images and such as Im geeking out watching this potential tornado outbreak unfold.


...LOWER MS VALLEY...MID-SOUTH AND TN VALLEY REGIONS...
TSTMS SHOULD BE INCREASING IN COVERAGE/INTENSITY AROUND BEGINNING OF
PERIOD OVER E TX...LA AND ARKLATEX REGION. FOREGOING AIR MASS --
ALREADY MOISTENED/DESTABILIZED FAVORABLY BY PRIOR/OVERNIGHT THETAE
ADVECTION...WILL FURTHER DESTABILIZE AMIDST SFC DIABATIC HEATING.
AMOUNT OF HEATING IS SOMEWHAT IN QUESTION BECAUSE OF POTENTIAL FOR
CLOUD/ANVIL DEBRIS SPREADING DOWNSTREAM IN MID-UPPER LEVELS FROM
EARLY CONVECTION...PERHAPS INCLUDING TEMPORAL EXTENSION OF ACTIVITY
NOW OVER S TX. STILL...AWAY FROM EXISTING CONVECTION...EVERY
REASONABLE SCENARIO INDICATES THAT MLCINH GENERALLY WILL WEAKEN WITH
NWD EXTENT FROM GULF COAST...SUPPORTING EARLY AND RAPID DEVELOPMENT
AND INTENSIFICATION OF TSTMS FROM MID-MORNING THROUGH
MID-AFTERNOON...AND SUSTAINED THREAT SHIFTING EWD AND NEWD ACROSS
OUTLOOK AREA INTO EVENING/OVERNIGHT HOURS.

INTENSE VERTICAL WIND PROFILES WILL SPREAD ACROSS BROAD WARM/MOIST
SECTOR TODAY...MUCH OF WHICH ALREADY IS IN PLACE ACROSS MUCH OF
LA...MS AND COASTAL AL. THIS AIR MASS WILL SPREAD INLAND TOWARD TN
VALLEY AS CONVECTION/PRECIP NOW OVER TN/AL/GA SHIFTS NEWD. SFC DEW
POINTS WILL BE 70S INVOF GULF COAST...TRANSITIONING TO UPPER 60S AS
FAR N AS TN AND LOW-MID 60S TO OH VALLEY. WEAKENING LAPSE RATES
ALOFT AND BUOYANCY WITH NWD EXTENT...FROM TN VALLEY TO OH VALLEY AND
GREAT LAKES...RENDER PROGRESSIVELY MORE CONDITIONAL NATURE TO SVR
THREAT...THOUGH KINEMATIC PROFILES WILL BECOME FAVORABLE OVER VERY
LARGE AREA S OF GREAT LAKES BY EVENING/OVERNIGHT HOURS.

MULTIPLE CONVECTIVE EPISODES AND STORM MODES ARE EXPECTED IN THIS
SITUATION...AGGREGATE OF WHICH SHOULD YIELD DENSE CONCENTRATION OF
SVR EVENTS BY END OF PERIOD ACROSS MDT/HIGH CATEGORICAL RISK AREAS.
THOUGH DISCRETE/CYCLIC TORNADIC SUPERCELLS ARE MOST POTENTIALLY
DANGEROUS THREAT...ESPECIALLY OVER HIGH RISK AREA...CLUSTERED AND
QUASI-LINEAR CONVECTIVE ELEMENTS WITH EMBEDDED BOW/LEWP FORMATIONS
AND SUPERCELLS ALSO APPEAR PROBABLE. STRENGTHENING DEEP-LAYER WINDS
AND RELATED FAST STORM MOTIONS PORTEND LONG TRACKS FOR SUPERCELLS
AND FOR SOME OF THEIR TORNADOES...AS WELL AS FOR SWATHS OF DAMAGING
WIND WITH ANY BOW/LEWP FEATURES. THIS SUPPORTS RATHER ROBUST
PROBABILITIES FOR ALL SEVERE MODES.

PARAMETER SPACES IN FCST SOUNDINGS OVER HIGH RISK AREA -- SHIFTING
NEWD FROM LATE MORNING THROUGH AFTERNOON -- INCLUDE 50-60 KT LLJ
SUPPORTING VERY LARGE HODOGRAPHS WITH 0-1 AND 0-1 KM SRH 300-600
J/KG. ALSO EXPECT 50-60 KT EFFECTIVE SHEAR MAGNITUDES BENEATH
110-140 KT 250 MB JET MAX AND 60-90 KT 500 MB WINDS...POTENTIALLY
JUXTAPOSED WITH MLCAPE 1500-2500 J/KG.

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