Tornado Alley Forecasts, Nowcasting and Reports

Cumulo · 21/04/2007, 20:13

Dal punto di vista sinottico mi sembra un gran pattern. E' un passaggio di una saccatura molto stretta e chiusa, e soprattutto con un'elevata elicità (ero molto scettico infatti sul fatto che i modelli non la mettessero, vedo ora che sia RUC che WRF hanno cambiato).
Il LLJ in questi casi si dimostra spesso la variabile più incisiva sull'entità dei fenomeni.
Di conseguenza penso a fenomeni che occuperanno un'area relativamente ristretta, ma molto proficua per fenomeni tornadici.
Questo ovviamente è sulla carta, poi il tempo fa ciò che vuole.

Giusto per fare un paragone: è una sinottica - soprattutto alle medio-alte quote - stile 07/07/2001 qui in Italia.

Io butto lì il mio target: Guymon, OK.

**Aragorth** · 21/04/2007, 22:53

Hey guys, I've been on the road all day today, finally at home able to monitor the USA

Man that looks outbreakable in the next hours!

I still like the play around Dumas, TX...latest VIS satellites leading into explosion in less than an hour over TX Panhandle

**Ben** · 21/04/2007, 23:03

ciao ragazzi

questa la salviamo, ok?

SEL7

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 157
NWS STORM PREDICTION CENTER NORMAN OK
345 PM CDT SAT APR 21 2007

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

THE OKLAHOMA PANHANDLE
WEST TEXAS AND THE TEXAS PANHANDLE

EFFECTIVE THIS SATURDAY AFTERNOON FROM 345 PM UNTIL MIDNIGHT CDT.

...THIS IS A PARTICULARLY DANGEROUS SITUATION...

DESTRUCTIVE TORNADOES...LARGE HAIL TO 2.5 INCHES IN DIAMETER...
THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE
POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 80 STATUTE
MILES EAST AND WEST OF A LINE FROM 20 MILES NORTH OF GUYMON
OKLAHOMA TO 10 MILES SOUTHWEST OF BIG SPRING TEXAS. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU7).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

OTHER WATCH INFORMATION...CONTINUE...WW 154...WW 155...WW 156...

DISCUSSION...TSTMS/SUPERCELLS EXPECTED TO FORM IN THE NEXT HOUR OR
SO IN NW PART OF WW AS LEE TOUGH/DRY LINE ACCELERATES ENE FROM NM.
ADDITIONAL STORMS MAY FORM INVOF CAPROCK ESCARPMENT/EDGE OF STRATOCU
FIELD IN THE TX PANHANDLE. VERY STRONG LOW TO MID LEVEL SHEAR
COUPLED WITH STEEP LOW TO MID LEVEL LAPSE RATES AND FAVORABLE-TIMED
ARRIVAL OF LARGE SCALE ASCENT EXPECTED TO SUPPORT A FEW LONG-LIVED
SUPERCELLS WITH TORNADOES/LARGE HAIL. ACTIVITY LIKELY TO EVOLVE
INTO BROKEN SEGMENTS WITH A CONTINUING THREAT FOR TORNADOES LATER
THIS EVENING AS NM VORT ACCELERATES NEWD.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 23040.

...CORFIDI

**Ben** · 21/04/2007, 23:05

anzi ci aggiungo pure questa (e' carina)

**Ben** · 21/04/2007, 23:17

quella nuvolosità su Amarillo nun me piace per niente

**Ben** · 21/04/2007, 23:32

convezione che parte alla grande ad ovest di Amarillo. Speriamo bene vada a conquistare quel corridoio..

**Ben** · 21/04/2007, 23:37

tornado watch nel frattempo

MESOSCALE DISCUSSION 0526
NWS STORM PREDICTION CENTER NORMAN OK
0532 PM CDT SAT APR 21 2007

AREAS AFFECTED...OK/TX PANHANDLES...TX SOUTH PLAINS AND PORTIONS OF
THE PERMIAN BASIN

CONCERNING...TORNADO WATCH 157...

VALID 212232Z - 220030Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 157 WILL INCREASE
THROUGH 01Z.

LEADING EDGE OF MID LEVEL COOLING/HEIGHT FALLS WAS SPREADING OVER
THE WRN EDGE OF THE INSTABILITY AXIS /JUST EAST OF A DRYLINE
EXTENDING FROM NEAR DHT TO HOB/. INCREASING CONVECTIVE TRENDS SEEN
ON VISIBLE SATELLITE IMAGERY OVER THE LAST 30 MIN TO 1 HR WILL
CONTINUE OVER THE NEXT SEVERAL HRS...WITH SEVERAL SUPERCELLS
EXPECTED TO DEVELOP OVER WRN PORTIONS OF WW 157 BY 00Z. A REMNANT
DIFFERENTIAL HEATING BOUNDARY GENERATED BY THE LOW CLOUD COVER OVER
THE ERN TX PANHANDLE FOR MUCH OF THE DAY HAS PUSHED WSWWD THROUGH
PORTIONS OF THE CENTRAL/SRN TX PANHANDLE AND NRN SOUTH PLAINS OVER
THE LAST FEW HRS. THIS BOUNDARY WAS EVIDENT BY SATELLITE AND RECENT
OBS AT AMA WHERE WINDS BACKED TO AROUND 130 DEG ALONG WITH A SLIGHT
COOLING. 22Z PLACEMENT OF THIS BOUNDARY WAS FROM JUST WEST OF AMA
SSWWD TO BRISCOE AND HALL COUNTIES. ANY SUPERCELLS THAT DEVELOP WEST
OF THIS BOUNDARY OVER THE WRN PANHANDLE AND WRN SOUTH PLAINS MAY
BECOME TORNADIC NEAR OF JUST EAST OF THIS BOUNDARY ACROSS THE
CENTRAL/SRN TX PANHANDLE AND NRN SOUTH PLAINS AREA BETWEEN 23-01Z
GIVEN THE PRESENCE OF VERY STRONG LOW LEVEL SHEAR /200-300 M2/S2 OF
0-1 KM SRH PER AMA VWP/ AND INCREASING 0-3 KM CAPE /AROUND 100 J/KG/
AS MID LEVEL COOLING OVERSPREADS THE AREA.

..CROSBIE.. 04/21/2007