Oklahoma Severe Weather Discussion - April 2011

[Thunder]

Translation and time frame, please. :-D

[Thunder]

Why is NWS predicting so different?

[venture]

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 201
NWS STORM PREDICTION CENTER NORMAN OK
1100 AM CDT MON APR 25 2011

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

WESTERN ARKANSAS
SOUTHEAST OKLAHOMA
NORTHEAST TEXAS

EFFECTIVE THIS MONDAY MORNING AND EVENING FROM 1100 AM UNTIL 600
PM CDT.

TORNADOES...HAIL TO 3 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 105 STATUTE
MILES EAST AND WEST OF A LINE FROM 5 MILES EAST SOUTHEAST OF
CORSICANA TEXAS TO 20 MILES WEST NORTHWEST OF FORT SMITH
ARKANSAS. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).

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 199...WW 200...

DISCUSSION...THUNDERSTORMS ARE INTENSIFYING OVER NORTHEAST TX AND
SOUTHEAST OK AS STRONG UPPER TROUGH APPROACHES FROM THE WEST. A
VERY MOIST AND MODERATELY UNSTABLE AIR MASS IS IN PLACE...WITH ONLY
A WEAK CAP. FAVORABLE LOW LEVEL AND DEEP LAYER VERTICAL
SHEAR...COMBINED WITH PRESENCE OF SURFACE BOUNDARIES...WILL PROMOTE
SUPERCELL THREAT. DAMAGING WINDS...VERY LARGE HAIL...AND A FEW
TORNADOES ARE ALL POSSIBLE THROUGH THE AFTERNOON IN THE WATCH AREA.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 3 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 25040.


TORNADO WATCH PROBABILITIES FOR WT 0201
NWS STORM PREDICTION CENTER NORMAN OK
1100 AM CDT MON APR 25 2011

WT 0201
PROBABILITY TABLE:
PROB OF 2 OR MORE TORNADOES : 60%
PROB OF 1 OR MORE STRONG /F2-F5/ TORNADOES : 40%
PROB OF 10 OR MORE SEVERE WIND EVENTS : 60%
PROB OF 1 OR MORE WIND EVENTS >= 65 KNOTS : 30%
PROB OF 10 OR MORE SEVERE HAIL EVENTS : 60%
PROB OF 1 OR MORE HAIL EVENTS >= 2 INCHES : 50%
PROB OF 6 OR MORE COMBINED SEVERE HAIL/WIND EVENTS : >95%

&&
ATTRIBUTE TABLE:
MAX HAIL /INCHES/ : 3.0
MAX WIND GUSTS SURFACE /KNOTS/ : 60
MAX TOPS /X 100 FEET/ : 500
MEAN STORM MOTION VECTOR /DEGREES AND KNOTS/ : 25040
PARTICULARLY DANGEROUS SITUATION : NO

[venture]

Severe storms are firing in Western Oklahoma and the TX panhandle. Movement is generally to the east.

Per the latest HRRR model, storms could eventually impact Central OK later this evening.

http://rapidrefresh.noaa.gov/hrrrcon...main=t5&wjet=1

[venture]

MESOSCALE DISCUSSION 0578
NWS STORM PREDICTION CENTER NORMAN OK
0524 PM CDT MON APR 25 2011

AREAS AFFECTED...ERN TX PANHANDLE...SWRN AND S-CNTRL OK

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 252224Z - 252330Z

ISOLATED THUNDERSTORMS...WITH SOME CAPABLE OF PRODUCING SVR
HAIL...HAVE DEVELOPED ACROSS THE TX PANHANDLE AND INTO WRN OK.
HOWEVER...THE THREAT IS EXPECTED TO REMAIN TOO DISCRETE/MARGINAL TO
WARRANT A WW.

PROMINENT UPPER VORT /EVIDENT ON RECENT WATER VAPOR IMAGERY/ HAS
SHIFTED INTO CNTRL OK...WITH A WEAK TRAILING IMPULSE MOVING ACROSS
NERN NM. THIS HAS AIDED IN INITIATING CONVECTION ACROSS PORTIONS OF
THE ERN TX PANHANDLE AND WRN OK AS COLD MIDLEVEL TEMPS /-18 TO -20
C/ HAVE YIELDED A MARGINALLY UNSTABLE ENVIRONMENT. STEEP MIDLEVEL
LAPSE RATES...ALONG WITH MODERATELY STRONG EFFECTIVE BULK SHEAR
AROUND 35 KTS...WILL CONTINUE TO SUPPORT THE POTENTIAL FOR SVR HAIL
WITH THE STRONGEST STORMS. THUNDERSTORM COVERAGE IS EXPECTED TO
DECREASE LATER THIS EVENING WITH THE LOSS OF DIABATIC HEATING.

..ROGERS.. 04/25/2011

[venture]

Special weather statement
national weather service norman ok
803 pm cdt mon apr 25 2011

okz023-027>031-033>042-044>047-051-txz083-085-260200-
caddo ok-pottawatomie ok-seminole ok-cleveland ok-grady ok-mcclain ok-
jackson ok-cotton ok-jefferson ok-kiowa ok-greer ok-tillman ok-
murray ok-johnston ok-comanche ok-garvin ok-marshall ok-harmon ok-
pontotoc ok-carter ok-stephens ok-hardeman tx-wilbarger tx-
803 pm cdt mon apr 25 2011

...significant weather advisory...

This significant weather advisory is for caddo...carter...
Cleveland...comanche...cotton...garvin...grady...g reer...hardeman...
Harmon...jackson...jefferson...johnston...kiowa... marshall...
Mcclain...murray...pontotoc...pottawatomie...semin ole...stephens...
Tillman and wilbarger counties.

As showers left over from dissipating thunderstorms move across
southwest and south central oklahoma...already gusty northerly winds
may be locally enhanced near and to the south of the showers. Wind
gusts up to 50 mph will be possible. A brief rise in temperature may
accompany strong wind gusts.

Hazards include...
Wind gusts to 50 mph...

[venture]

Today's risk is a pretty mixed bag across the state. The SPC outlook really doesn't cover too much for us. Basically we have a slight risk for most of Southern OK from I-40 south - including parts of the southern Metro area. A tornado outbreak is expected this afternoon/this evening to our southeast. A Moderate risk exists for extreme southeast OK and a High Risk for the very southeastern tip of Oklahoma.

The Norman forecast office has a good graphic to sum up what to expect around here...

Update - OUN expanded their slight risk outlook back into NW OK now.

[venture]

Only impacts far SE OK, but thought this was a unique, strongly worded MCD that it still should be posted.



MESOSCALE DISCUSSION 0589
NWS STORM PREDICTION CENTER NORMAN OK
0111 PM CDT TUE APR 26 2011

AREAS AFFECTED...NORTHEAST TX AND FAR SOUTHEAST OK/NORTHERN
LA/SOUTHERN AR

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY

VALID 261811Z - 262015Z

THE SEVERE THREAT IS EXPECTED TO STEADILY INCREASE THROUGH MID/LATE
AFTERNOON...INITIALLY ACROSS PORTIONS OF NORTHEAST TX AND INTO
SOUTHEAST OK/NORTHERN LA/SOUTHERN AR. A RELATIVELY LONG LEAD
TIME/DURATION PARTICULARLY DANGEROUS SITUATION /PDS/ TORNADO WATCH
WILL LIKELY BE ISSUED BY MID AFTERNOON.

WITH SURFACE CYCLOGENESIS UNDERWAY ACROSS THE SOUTHERN HIGH
PLAINS...THE WARM SECTOR AIRMASS...EAST OF A NEAR I-35 CENTRAL TX
DRYLINE...AND ALONG/SOUTH OF A SLOW NORTHWARD-RETURNING
SOUTHWEST-NORTHEAST ORIENTED FRONTAL BOUNDARY FROM THE SOUTH DFW
METRO INTO SOUTHERN AR...HAS ALREADY BECOME MODERATE TO STRONGLY
UNSTABLE IN THE PRESENCE OF LITTLE CINH. AFTER A BRIEF BOUT OF
SHORTWAVE RIDGING AT MIDDAY...THE LEADING EDGE OF AN UPPER JET
STREAK APPEARS TO HAVE REACHED THE SOUTHERN HIGH PLAINS...WITH
LIKELY-ASSOCIATED DEEP MIXED CUMULIFORM DEVELOPMENT NOW EVIDENT
ACROSS EASTERN NM/NORTHWEST TX PER VISIBLE SATELLITE IMAGERY.
INCREASING DEEP LAYER WIND FIELD ATOP THE MOIST/UNSTABLE WARM SECTOR
WILL BE HIGHLY FAVORABLE FOR SUPERCELLS WITH AN INCREASING LARGE
HAIL/TORNADO THREAT INTO THIS EVENING. STRENGTHENING LOWER
TROPOSPHERIC WINDS THIS EVENING WILL ACCENTUATE THE RISK OF STRONG
TORNADOES ESPECIALLY ACROSS THE ARKLATEX VICINITY/ADJACENT FAR
SOUTHEAST OK.

[venture]

Catching up on the watches.



URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 221
NWS STORM PREDICTION CENTER NORMAN OK
510 PM CDT TUE APR 26 2011

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

PARTS OF NORTHERN ARKANSAS
PARTS OF EASTERN OKLAHOMA

EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 510 PM UNTIL
1000 PM CDT.

SEVERAL TORNADOES
ISOLATED INTENSE TORNADOES POSSIBLE
SCATTERED DAMAGING WINDS
ISOLATED WIND GUSTS TO 70 MPH POSSIBLE
SCATTERED LARGE HAIL
ISOLATED HAIL TO 3.0 INCHES IN DIAMETER POSSIBLE

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 55 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 25 MILES SOUTHWEST OF
MCALESTER OKLAHOMA TO 10 MILES EAST NORTHEAST OF BATESVILLE
ARKANSAS. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).

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 213...WW 214...WW
215...WW 216...WW 217...WW 218...WW 219...WW 220...

DISCUSSION...SEVERE THUNDERSTORMS INCLUDING SUPERCELLS ARE
DEVELOPING VICINITY WARM FRONTAL ZONE ACROSS THE WATCH. WITH SHEAR
CONTINUING TO INCREASE SUPERCELLS WILL INCLUDE BOTH LARGE HAIL AND
TORNADO THREAT.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 3 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 24035.



URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 218
NWS STORM PREDICTION CENTER NORMAN OK
345 PM CDT TUE APR 26 2011

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

SOUTHERN OKLAHOMA
WESTERN NORTH TEXAS

EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 345 PM UNTIL
1000 PM CDT.

WIDELY SCATTERED DAMAGING WINDS
ISOLATED WIND GUSTS TO 70 MPH POSSIBLE
WIDELY SCATTERED LARGE HAIL TO 2.0 INCHES IN DIAMETER
ISOLATED TORNADOES

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 55
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 40 MILES WEST OF
ALTUS OKLAHOMA TO 20 MILES NORTH NORTHEAST OF DURANT OKLAHOMA.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU8).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR 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. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

OTHER WATCH INFORMATION...CONTINUE...WW 213...WW 214...WW
215...WW 216...WW 217...

DISCUSSION...SCATTERED THUNDERSTORMS HAVE DEVELOPED IN THE LEFT-EXIT
REGION OF A STRONG MID/UPPER LEVEL JET OVER THE TX PANHANDLE. THESE
STORMS ARE LIKELY TO TRACK EASTWARD ACROSS SOUTHERN OK AND WESTERN
NORTH TX THROUGH THE LATE AFTERNOON AND EVENING. VERTICAL SHEAR
PROFILES SUPPORT ROTATING STORMS CAPABLE OF HAIL AND DAMAGING WINDS.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM
MOTION VECTOR 27035.

[venture]

Okay, that time again for a look into the future that is obviously going to be wrong...but its still fun and interesting.

Through early Wednesday...expect a chance for some scattered showers and storms north of I-40 (or pretty close). Some hail might be mixed in but nothing major. Looks dry after that until oh...Saturday.

Saturday looks like a boundary will be settling in from the NW. Ahead of the front wind swill be out of the SE turning to the SW (NW behind the front). By late afternoon the front should setup pretty close to the I-44 corridor (either side of it). Ahead of the front instabilities will be increasing into the moderate to high categories. Moisture will also be flowing in from the Gulf with dewpoints approaching the low 70s in South Central OK. Some showers and storms are expected to flow along the front by this time frame and increase in coverage overnight. Storms appear to be probably along and south of I-44 from NE OK into the OKC metro area to about Chickasha. Rainfall could be heavy in this area, especially south of I-40 where amounts could get well over 1 inch. Scattered showers will be possible throughout the rest of the state...especially north of I-40.

Sunday May 1st - Appears to be fairly cool across most of the state. Temps may only get into the 50s and 60s for most of the state, except SE OK. Showers and storms will be pushing out across eastern OK as the day goes on and out of the state by midnight (give or take).

May 2nd and 3rd look dry. The 4th looks dry too but some changes on the way. Moisture will increase through the day and temps will warm up to be pretty mild. Overnight storms are possible to form going into May 5th.

Thursday May 5th - Storms may be on going across Southern OK roughly along and south of I-40. As it appears right now, severe threat should be low with this being mostly moderate rain and some hail here and there. Areas south of I-40 could see over 1 inch of rain and less north of I-40.

Dry May 6th and most of the 7th.

Saturday May 7th - Winds will again be out of the SE and will push moisture up from the Gulf. Dewpoints should reach the low 60s and temps into the 70s and 80s. Cap will be fairly strong this day, so not a lot of convection ahead. There could be one or two storms with moderate instability around.

Sunday May 8th - One to watch. ...but we are so far out, these days tend to vanish on the next model run. SE winds will continue to bring moisture into the state. Dewpoints are expected to be in the mid 60s to near 70 across most of Central Oklahoma (Central 1/3rd). Forecase CAPE values are 3000 to 4500 j/kg with LI values -10 to -13. Forecasts precip amounts are pretty low which would indicate mostly isolated activity. Again, a long ways out but a day with numbers like this would definitely be a high end severe weather day...but I don't see this sticking around very long. Looks back at the various model runs, the 00Z run for the last couple of days has continued to highlight this as a high end severe weather day...but the 6Z, 12Z and 18Z runs keep bouncing back and forth to nothing or eastern OK or NW OK or every other possible scenario in a 300 mile radius.

Monday May 9th - We'll see a surface low kick out from the Southern Plains to the Mid Mississippi Valley area. This will cool things down, have some associated showers/storms in the north during the morning but that's about it.

Dry and cool with a slow warming trend into the 11th and 12th.

Thursday May 12 - Chance of storms anywhere in the Plains states, but precip doesn't look all that probably right now. Still...384 hours out, this forecast has a 0.1% of really being accurate. LOL

So that's all we have coming it looks like right now. So far pretty tame compared to the mid section and SE section of the nation. Of course, as we all know, it only takes one day...one 6 hour period to make it a record breaking severe weather season in Oklahoma.

[venture]

Slight risk of severe weather Saturday across far southern OK.

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0224 AM CDT THU APR 28 2011

VALID 301200Z - 011200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF N TX AND
ADJACENT SRN OK...

...SYNOPSIS...
A WRN U.S. UPPER TROUGH IS FORECAST TO CONTINUE SLOWLY
DIGGING/PROGRESSING EWD/SEWD WITH TIME...DISASSEMBLING INTO TO
SMALLER-SCALE TROUGHS WITH TIME -- A MORE NRN SHORT-WAVE FEATURE
MOVING MORE QUICKLY ACROSS THE UPPER MS VALLEY REGION AND INTO THE
UPPER GREAT LAKES LATE...AND A SECOND FEATURE WHICH WILL CONTINUE
SLOWLY DIGGING SSEWD OUT OF THE GREAT BASIN INTO AZ/NM.

AS THE UPPER SYSTEM EVOLVES...THE NRN PORTION OF THE SURFACE COLD
FRONT CROSSING THE PLAINS WILL CONTINUE EWD ACROSS THE N CENTRAL
PORTION OF THE CONUS...CROSSING THE UPPER GREAT LAKES/UPPER MIDWEST
LATE. MEANWHILE...THE FRONT SHOULD MOVE MUCH MORE SLOWLY SEWD
ACROSS THE SRN PLAINS...LIKELY SLOWING OR EVEN STALLING AND LAYING
OUT ROUGHLY W-E ACROSS N TX BY LATE IN THE PERIOD. WHILE SHOWERS
AND A FEW THUNDERSTORMS WILL BE POSSIBLE ALONG THE FRONT FROM THE
UPPER MIDWEST SWWD INTO THE ARKLATEX REGION DURING THE DAY...MAIN
SEVERE POTENTIAL SHOULD EVOLVE LATE IN THE PERIOD OVER PARTS OF
TX/OK IN CONJUNCTION WITH THE DEVELOPING LOW-LEVEL JET.

...RED RIVER VALLEY REGION OF SRN OK/N TX...
AS UPPER HEIGHTS FALL ACROSS THE SRN PLAINS REGION AHEAD OF THE MAIN
TROUGH...STRONG SLY LOW-LEVEL JET IS FORECAST TO DEVELOP IN RESPONSE
DURING THE EVENING HOURS OF DAY 3 /SAT. 4-30/ OVER CENTRAL AND N TX.
WITH THE ROUGHLY W-E PORTION OF THE SURFACE FRONT PROGGED TO LIE
ACROSS N TX DURING THE SECOND HALF OF THE PERIOD...STRONG ISENTROPIC
LIFT/WARM ADVECTION SHOULD LEAD TO AN INCREASE IN COVERAGE OF
ELEVATED STORMS. WITH RELATIVELY STEEP LAPSE RATES ALOFT AND 50 KT
WSWLY MID-LEVEL FLOW EXPECTED...SHEAR/INSTABILITY COMBINATION
APPEARS SUFFICIENT TO SUPPORT THREAT FOR HAIL WITH A FEW
STRONGER/POSSIBLY ROTATING STORMS.

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 15 SW DEQ 35 NNE TYR 35 S FTW 30 WSW MWL 35 SW SPS 30 S CHK 45 SE OKC 40 SE MLC 15 SW DEQ.

[venture]

Still going through the model runs for this evening. May 7th. Original we were looking at the 8th, but GFS moving it up a little faster and right now, this could be a day to be extremely concerned about. Still early in my run through, but quick glance just had ridiculous forecast soundings for the area. More later in the new thread.