Tras la tormenta invernal que ha azotado a los estados del norte y del centro, con nieve y tornados respectivamente, de cara al día de Navidad se espera el desarrollo de otra baja presión, a baja latitud, que podría traer asociado un episodio de tiempo severo por tormentas y tornados... Habrá que seguirlo a ver.

ZCZC SPCSWOD48 ALL
   ACUS48 KWNS 220958
   SPC AC 220958
   
   DAY 4-8 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   0358 AM CST SAT DEC 22 2012
   
   VALID 251200Z - 301200Z
   
   ...DISCUSSION...
   THE MEDIUM RANGE MODELS MOVE A PROGRESSIVE UPPER-LEVEL TROUGH
   QUICKLY ESEWD ACROSS THE ROCKIES MONDAY NIGHT AND INTO THE SRN
   PLAINS ON TUESDAY/DAY 4. STRONG LARGE-SCALE ASCENT AND MOISTURE
   RETURN AHEAD OF THE SYSTEM WILL ALLOW SCATTERED TO NUMEROUS
   THUNDERSTORMS TO DEVELOP ACROSS THE TX COASTAL PLAINS AND IN THE
   LOWER MS VALLEY FROM LATE MONDAY NIGHT INTO TUESDAY. AS THE EXIT
   REGION OF A POWERFUL MID-LEVEL JET NOSES INTO THE LOWER MS
   VALLEY...SEVERE STORMS WILL BE POSSIBLE DUE TO STRONG DEEP LAYER
   SHEAR AND WIDESPREAD ASCENT. THE PROGRESSIVE NATURE OF THE SYSTEM
   MAY ENABLE A SQUALL-LINE TO ORGANIZE AND QUICKLY MOVE EWD ACROSS THE
   LOWER MS VALLEY ON TUESDAY AND INTO THE CNTRL GULF COAST STATES. IT
   APPEARS THAT A SUBSTANTIAL SEVERE WEATHER THREAT WILL BE POSSIBLE ON
   TUESDAY AND TUESDAY NIGHT ACROSS A BROAD CORRIDOR FROM SE TX
   EXTENDING ENEWD ACROSS LA...MS ...AL AND INTO THE FL PANHANDLE.
   
   AS THIS SYSTEM CONTINUES TO MOVE ENEWD INTO THE CAROLINAS ON
   WEDNESDAY/DAY 5...A SEVERE THREAT WILL CONTINUE TO BE POSSIBLE. AN
   ENHANCED SEVERE THREAT COULD OCCUR IF A LINEAR MCS OR A CLUSTER OF
   SEVERE STORMS MOVES INTO THE REGION FROM THE WEST LATE TUESDAY
   NIGHT. AT THIS POINT...WILL NOT ISSUE AN OUTLOOK AREA FOR THE
   CAROLINAS UNTIL CONFIDENCE IS A BIT GREATER CONCERNING THE TIMING OF
   THE UPPER-LEVEL TROUGH. BY LATE IN THE DAY 4 TO 8 PERIOD...THE
   MODELS MOVE ANOTHER UPPER-LEVEL TROUGH INTO THE CNTRL U.S. THIS
   COULD BE FAVORABLE FOR STRONG THUNDERSTORMS IN THE LOWER TO MID MS
   VALLEY AGAIN ON FRIDAY/DAY 7 BUT MUCH UNCERTAINTY EXISTS AT THIS
   RANGE.
   
   ..BROYLES.. 12/22/2012

El episodio comienza a iniciarse con esa banda nubosa sobre la que se formará una borrasca.-

Las probabilidades de que se produzca un outbreak tornádico van aumentando... Diversos medios de comunicación americanos se van haciendo eco de forma cada vez más importante.

SPC AC 240653
   
   DAY 2 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   1253 AM CST MON DEC 24 2012
   
   VALID 251200Z - 261200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF LA...SCNTRL MS
   AND WCNTRL AL...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
   PLAINS...LOWER MS VALLEY...TN VALLEY...ERN GULF COAST STATES AND SRN
   APPALACHIAN MTNS...
   
  ...SIGNIFICANT SEVERE WEATHER EVENT SETTING UP FOR CHRISTMAS DAY FOR
   PARTS OF THE GULF COAST STATES...
   
   ...LOWER MS VALLEY/GULF COAST STATES...
   AN IMPRESSIVE UPPER-LEVEL SYSTEM IS FORECAST TO MOVE ACROSS THE SRN
   PLAINS INTO THE LOWER MS VALLEY ON TUESDAY. A POWERFUL MID-LEVEL JET
   IN THE BASE OF THE UPPER-LEVEL SYSTEM WILL TRANSLATE QUICKLY EWD
   OVER A MOISTENING WARM SECTOR RESULTING IN THE POTENTIAL FOR A
   SIGNIFICANT SEVERE WEATHER EVENT ACROSS PARTS OF THE LOWER MS VALLEY
   AND CNTRL GULF COAST STATES. AS THE UPPER-LEVEL TROUGH APPROACHES
   THE REGION...MODEL FORECASTS MOVE A BAND OF STRONG LARGE-SCALE
   ASCENT QUICKLY EWD ACROSS CNTRL TX EARLY TUESDAY MORNING WHICH
   COINCIDES WITH A MOISTENING BOUNDARY LAYER ACROSS MUCH OF THE TX
   COASTAL PLAINS. IN RESPONSE...THUNDERSTORM DEVELOPMENT SHOULD BE
   UNDERWAY AT DAYBREAK ON TUESDAY WITH A CLUSTER OF STRONG TO
   POTENTIALLY SEVERE STORMS MOVING ENEWD FROM SE TX INTO THE LOWER MS
   VALLEY AROUND MIDDAY.
   
   FORECAST SOUNDINGS AT VICKSBURG AND JACKSON MS ON TUESDAY GRADUALLY
   DEVELOP MODERATE INSTABILITY WITH SFC DEWPOINTS REACHING THE LOWER
   TO MID 60S F. THIS COMBINED WITH STRENGTHENING DEEP LAYER SHEAR AS
   0-6 KM SHEAR APPROACHES 60 KT BY EARLY AFTERNOON SHOULD BE FAVORABLE
   FOR SUPERCELLS AND TORNADOES. 0-3 KM STORM RELATIVE HELICITIES OF
   350 TO 400 M2/S2 SHOULD BE SUPPORTIVE OF STRONG TORNADOES WITH THE
   GREATEST THREAT ALONG A CORRIDOR FROM NEAR LAKE CHARLES LA TUESDAY
   MORNING ACROSS SCNTRL MS INTO WCNTRL AL BY TUESDAY EVENING.
   INSTABILITY...MOISTURE AND SHEAR PROFILES SUGGEST THAT ANY MCS THAT
   BECOMES WELL-ORGANIZED COULD CONTAIN A TORNADO THREAT FOR AN
   EXTENDED PERIOD. FOR THIS REASON...LONG TRACK TORNADOES COULD OCCUR
   WITH SUPERCELLS THAT REMAIN DISCRETE AND MOVE ALONG THE NRN EDGE OF
   MODERATE INSTABILITY. IN ADDITION...WIND DAMAGE WILL BE LIKELY WITH
   LINE-SEGMENTS THAT ORGANIZE ON THE LEADING EDGE OF THE MCS. A THREAT
   FOR WIDESPREAD WIND DAMAGE MAY DEVELOP ACROSS THE REGION TUESDAY
   WITH WIND GUSTS OVER 70 KT POSSIBLE WITH BOWING SEGMENTS EMBEDDED IN
   THE LINE. IF A WELL-DEVELOPED AND FAST MOVING SQUALL-LINE
   ORGANIZES...THEN THE WIND DAMAGE THREAT COULD BECOME SUBSTANTIAL.
   THE THREAT FOR SEVERE STORMS SHOULD CONTINUE THROUGH MUCH OF THE
   OVERNIGHT PERIOD REACHING THE SRN APPALACHIAN MTNS AND ERN GULF
   COAST STATES LATE TUESDAY NIGHT.
   
   ..BROYLES.. 12/24/2012
   
   CLICK TO GET WUUS02 PTSDY2 PRODUCT

 (:B) (:B) (:B) (:B) (:B) Podría tratarse de una oleada extraordinaria para las fechas en que estamos...

En los estados del sureste ya hay una buena banda de tormentas... pero creo que no se corresponden con esta situación

Además, condiciones de tiempo invernal en Oklahoma, con nieve... cosa poco usual en el área,,,

MESOSCALE DISCUSSION 2204
   NWS STORM PREDICTION CENTER NORMAN OK
   0232 AM CST TUE DEC 25 2012
   
   AREAS AFFECTED...PORTIONS OF WESTERN AND CENTRAL OKLAHOMA
   
   CONCERNING...WINTER MIXED PRECIPITATION
   
   VALID 250832Z - 251230Z
   
   SUMMARY...SNOW...SLEET AND FREEZING RAIN WILL IMPACTS PARTS OF
   WESTERN AND CENTRAL OK THE NEXT FEW HOURS. WHILE PRECIPITATION IS
   EXPECTED TO BE SCATTERED AND LIGHT...HAZARDOUS TRAVEL CONDITIONS CAN
   DEVELOP WITH ONLY SMALL ICE ACCUMULATION.
   
   DISCUSSION...LOW LEVEL MOISTURE WAS BEING TRANSPORTED INTO THE AREA
   VIA ELY LOW LEVEL FLOW /AS EVIDENT IN KTLX 88-D VWP DATA/. AN
   INITIAL SHORTWAVE IMPULSE MOVING ACROSS CENTRAL OKLAHOMA EARLY THIS
   MORNING AHEAD OF THE MAIN UPPER TROUGH WAS PROVIDING FORCING FOR
   ASCENT AND RESULTING IN LIGHT WINTRY MIX PRECIP TYPES. FREEZING
   RAIN/SLEET AND SNOW RATES WILL BE LOW THE NEXT FEW HOURS AS MIDLEVEL
   MOISTURE ONLY SLOWLY INCREASES. HOWEVER...LIGHT ACCUMULATIONS OF
   SLEET AND FREEZING RAIN ON ROADWAYS WILL LEAD TO HAZARDOUS TRAVEL
   CONDITIONS. AS MID LEVEL TEMPERATURES COOL AFTER SUNRISE...SLEET MAY
   MIX WITH SNOW FOR A BRIEF PERIOD BEFORE A TRANSITION TO ALL SNOW
   OCCURS AND PRECIPITATION BECOMES HEAVIER.
   
   ..LEITMAN.. 12/25/2012
   
   
   ATTN...WFO...TSA...OUN...
   
   LAT...LON   34689926 35049947 35699940 36289885 36409816 36439732
               36479686 36349657 35899631 35119626 34819638 34569688
               34509742 34459799 34559871 34689926

Merece la pena citar a Marko Korosec....

holy shit WOW!!!! Monster hook with likelihood of debris ball just N of MvNeill, MS right now!

Dos líneas principales en estos momentos, y continuamente activándose avisos por tornados... Menudas horas les esperan a estos estados del sur y sureste... Y ojo al movimiento hacia el noreste de la borrasca a la que van asociados estos sistemas de tormentas

28 reportes de tornado en la jornada de ayer: