Feb 1-4 Plains Severe Weather Threat, SPC Risk Level: Day 1-3 Slight Risk - Forecasts & OBS Options

[The Day After To...]

The threat is there. 12z GFS LI at hour 150, and 6 hour accum precip at 156.

Source 1
Source 2

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[The Day After To...]

Precip didn't upload right.

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[jdrenken]

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0357 AM CST SAT JAN 28 2012

VALID 311200Z - 051200Z

THE MEDIUM RANGE MODELS BEGIN THE DAY 4 TO 8 PERIOD WITH WEST TO
SOUTHWEST FLOW OVER MUCH OF THE CONUS. BOTH THE ECMWF AND GFS
DEVELOP AN UPPER-LEVEL TROUGH OVER THE SWRN STATES ON TUESDAY/DAY 4.
AHEAD OF THIS SYSTEM ON TUESDAY...LOW-LEVEL MOISTURE IS FORECAST TO
RETURN NWD ONTO THE TX COASTAL PLAINS AND INTO THE LOWER TO MID-MS
VALLEY. THUNDERSTORMS COULD DEVELOP FROM THE TX COAST EWD ACROSS THE
GULF COAST STATES FROM WEDNESDAY/DAY 5 INTO THURSDAY/DAY 6 AS THE
UPPER-LEVEL TROUGH APPROACHES FROM THE WEST. ALTHOUGH THE TIMING OF
THE UPPER-LEVEL TROUGH IS STILL QUESTIONABLE...THE MODELS MOVE THE
SYSTEM EWD ACROSS THE SRN PLAINS AND CNTRL GULF COAST STATES ON
FRIDAY/DAY 7 AND SATURDAY/DAY 8 SUGGESTING THE THREAT FOR CONVECTION
WOULD SHIFT EWD INTO THE ERN GULF COAST STATES. FORECAST INSTABILITY
IS EXPECTED TO REMAIN WEAK ALONG THE GULF COAST IN THE MID TO LATE
WEEK TIME-FRAME. FOR THIS REASON...ANY SEVERE THREAT WOULD LIKELY BE
MARGINAL AND NO ENHANCED SEVERE THREAT AREA IS FORECAST ATTM.

..BROYLES.. 01/28/2012

[The Day After To...]

JD, have thier been any instances were 'outbreak potentials' develop in the <5 day range?

[jdrenken]

JD, have thier been any instances were 'outbreak potentials' develop in the <5 day range?

Yes...and the SPC is quick to mention them in the Day 4-8 outlooks...hence why I posted their thoughts not being sold on anything.

[The Day After To...]

I meant where things looked flat about 6 days out, and then things changed in the direction of a severe weather outbreak. I may have understood your post wrong.

[The Day After To...]

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0356 AM CST SUN JAN 29 2012

VALID 011200Z - 061200Z

THE MEDIUM RANGE MODELS BEGIN THE DAY 4 TO 8 PERIOD WITH AN
UPPER-LEVEL TROUGH IN THE CNTRL STATES ON WEDNESDAY/DAY 4. THE ECMWF
AND GFS DIVERGE QUICKLY WITH THEIR SOLUTIONS WITH THE ECMWF MOVING
THE SYSTEM EWD INTO THE MS VALLEY WEDNESDAY NIGHT AND INTO THE
APPALACHIAN MTNS ON THURSDAY. THE GFS IS LESS AMPLIFIED WITH THE
WAVE AND IS ABOUT 12 HOURS SLOWER BUT BOTH MODELS DEVELOP
THUNDERSTORMS IN THE CNTRL GULF COAST STATES AS THE SYSTEM MOVES
ACROSS. AT THIS POINT...PREFER THE ECMWF WHICH DEVELOPS
THUNDERSTORMS IN THE LOWER TO MID MS VALLEY LATE WEDNESDAY NIGHT AND
MOVES THE STORMS EWD ACROSS THE OH AND TN VALLEYS ON THURSDAY/DAY 5.
AFTER THE SYSTEM EXITS THE ERN SEABOARD ON THURSDAY NIGHT...THE
MODELS DEVELOP A LARGE UPPER-LEVEL TROUGH ACROSS THE CNTRL AND ERN
STATES ON FRIDAY/DAY 6. THUNDERSTORMS COULD DEVELOP ONCE AGAIN IN
THE ERN GULF COAST STATES TO THE EAST OF THE TROUGH AXIS BUT
UNCERTAINTY IS HIGH CONCERNING THIS SCENARIO AND THROUGHOUT THE
UPCOMING WEEK. FOR THIS REASON...WILL NOT INCLUDE AN ENHANCED SEVERE
THREAT AREA IN THE DAY 4 TO 8 PERIOD.

http://www.spc.noaa.gov/products/exper/day4-8/

[The Day After To...]

Anyone know how the ECM looks for severe wx during the 1-5 time frame?

[Superstorm93]

Anyone know how the ECM looks for severe wx during the 1-5 time frame?

FULL ECM provided by WU with CAPE and whatever else you may need.

[The Day After To...]

Is the CAPE not working? It doesn't show anything when I try it. The Shear works, the MSL works.

[Superstorm93]

Is the CAPE not working? It doesn't show anything when I try it. The Shear works, the MSL works.

Not sure, I'll try AccuPro later.

[The Snowman]

I think this is the right thread.
Storm looks to start off positively tilted but seems to quickly try and go to a negative tilt, per GFS.
Source

[The Day After To...]

What is more favorible for severe wx, negative, positive, or netrual tilt?

[The Snowman]

What is more favorible for severe wx, negative, positive, or netrual tilt?

Negative tilt.
The horrible storms the South experienced earlier this month were from a negative tilted storm.

[The Day After To...]

I will issue a Day 3/WED forecast before I go to bed tonight, after the NAM runs.

[The Day After To...]

Severe Weather Forecast Center
Forecaster: TDAT

Day 3 forecast:
Possibility of storms over parts of the SC CONUS.....


Parameters
LI: -2 to -7
CAPE: 500 to 2000
0-3 km EHI: .25-2.50
Overall Parameters: Marginal

Overview
A storm system is supposed to develop on the 1st, and there is the possibility of thunderstorms. NOTE: This forecast is based on the 00z NAM.
Map

Sources
http://www.twisterdata.com/index.php?prog=...p;archive=false
Twisterdata NAM. Different frames too, of course.

Next Update: Tommorow night...or maybe afternoon/evening.

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[The Day After To...]

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0224 AM CST MON JAN 30 2012

VALID 011200Z - 021200Z

A SHORTWAVE TROUGH IS FORECAST TO MOVE EWD INTO THE SRN PLAINS AND
ARKLATEX WEDNESDAY INTO WEDNESDAY NIGHT. HOWEVER...MODEL FORECASTS
ARE QUITE DIFFERENT ON THE AMPLITUDE AND SPEED OF THE TROUGH. THE
NAM IS THE SLOWEST WITH THE WAVE ALLOWING FOR LOW-LEVEL MOISTURE TO
RETURN NWD ACROSS MUCH OF CNTRL AND EAST TX. THE GFS AND ECMWF ARE
FASTER WITH THE WAVE AND CONFINE MOISTURE RETURN TO EAST TX AND LA.
THE MODEL SOLUTIONS DO AGREE THAT CONVECTION WILL INITIATE AHEAD OF
THE AXIS OF THE SHORTWAVE TROUGH ON THE NRN EDGE OF THE MOIST AXIS
WEDNESDAY EVENING. FORECAST SOUNDINGS IN NE TX WEDNESDAY EVENING
SUGGEST THAT INSTABILITY WILL BE SUFFICIENT FOR HAIL WITH MUCAPE
VALUES OF 1000 TO 1500 J/KG. IF ELEVATED THUNDERSTORMS CAN INITIATE
ACROSS NE TX WEDNESDAY EVENING...THEN A THREAT FOR HAIL COULD EXIST.
THE MAIN PROBLEM IS THE DIFFERENCE IN MODEL SOLUTIONS. AT THIS
POINT...HAVE TAKEN A COMPROMISE BETWEEN THE GFS/ECMWF AND NAM
SOLUTIONS. MUCH UNCERTAINTY EXISTS AT THIS POINT AND LATER RUNS WILL
HELP CLARIFY THE POTENTIAL FOR A HAIL SCENARIO.

Day 3

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0346 AM CST MON JAN 30 2012

VALID 021200Z - 071200Z

THE MEDIUM RANGE MODELS BEGIN THE DAY 4 TO 8 PERIOD WITH AN
UPPER-LEVEL TROUGH IN THE ROCKIES. THE UPPER-LEVEL TROUGH BECOMES
NEGATIVELY-TILTED AND AMPLIFIES ON THURSDAY/DAY 4 AND THURSDAY NIGHT
AS A MID-LEVEL JET MOVES INTO THE SRN PLAINS. AT THE SFC...THE
MODELS MOVE A COLD FRONT SEWD ACROSS THE SRN PLAINS THURSDAY NIGHT
AND DEVELOPS CONVECTION ALONG THE BOUNDARY LATE. THIS CONVECTION
MOVES QUICKLY SEWD ONTO THE TX COASTAL PLAINS AND LOWER MS VALLEY ON
FRIDAY/DAY 5 WHERE THE MODELS SHOW SFC DEWPOINTS IN THE LOWER TO MID
60S F. THIS ALONG WITH SUBSTANTIAL VERTICAL SHEAR ASSOCIATED WITH
THE MID-LEVEL JET COULD BE ENOUGH FOR A SEVERE THREAT ACROSS THE SRN
PLAINS AND LOWER MS VALLEY FRIDAY AFTERNOON AND EVENING. THE GFS
MOVES THE POTENTIAL FOR THUNDERSTORMS EWD INTO THE OH AND TN VALLEYS
ON SATURDAY/DAY 6 AND ACROSS THE ERN SEABOARD SATURDAY NIGHT. ON THE
CONTRARY...THE ECMWF KEEPS THE UPPER-LEVEL SYSTEM BACK TO THE WEST
OVER THE ROCKIES AND CNTRL PLAINS. FOR THIS REASON...UNCERTAINTY IS
HIGH LATE IN THE WEEK CONCERNING THE POTENTIAL FOR SEVERE STORMS.
MORE CERTAINTY EXISTS FOR A SEVERE THREAT IN THE SRN PLAINS AND
LOWER MS VALLEY FRIDAY BUT THE MAGNITUDE OF THE THREAT REMAINS
QUESTIONABLE. WILL NOT INTRODUCE AN ENHANCED SEVERE THREAT ATTM.

..BROYLES.. 01/30/2012

Day 4-8

[WeatherMonger]

Looks like the date needs changed to start tomorrow and may need extended a day or so by the Day 4-8 outlook. Like hearing the Mid-Mississippi valley but am sure I'm too far north to benefit.

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0354 AM CST TUE JAN 31 2012

VALID 031200Z - 081200Z

THE MEDIUM RANGE MODELS BEGIN THE DAY 4 TO 8 PERIOD WITH A
NEGATIVELY-TILTED UPPER-LEVEL TROUGH OVER THE SRN ROCKIES AND AN
EJECTING MID-LEVEL JET ACROSS THE SRN PLAINS. THE MODELS COUPLE THE
LOW AND MID-LEVEL JET ACROSS THE SRN PLAINS ON FRIDAY/DAY 4 AS A
STRONG SYSTEM MOVES INTO THE SRN PLAINS. FOCUSED LARGE-SCALE
ASCENT...ADEQUATE INSTABILITY AND MODERATE TO STRONG DEEP LAYER
SHEAR SHOULD BE SUFFICIENT FOR SEVERE THUNDERSTORMS IN PARTS OF EAST
AND NORTH TX FRIDAY AFTERNOON AND EVENING. FROM HERE UNCERTAINTY
INCREASES AS THE MODELS MOVE THE MOIST SECTOR SEWD INTO THE GULF
COAST STATES. STRONG THUNDERSTORMS WILL BE POSSIBLE ACROSS THE LOWER
TO MID-MS VALLEY EARLY ON SATURDAY/DAY 5 AND IN THE CNTRL GULF COAST
STATES SATURDAY AFTERNOON. ON SUNDAY/DAY 6 AND MONDAY/DAY 7...THE
MODELS MOVE A COLD FRONT ACROSS THE SERN STATES WHERE THUNDERSTORMS
MAY DEVELOP ALONG THE BOUNDARY BUT UNCERTAINTY IS QUITE HIGH BY
EARLY NEXT WEEK. AT THIS POINT...IT APPEARS THAT A SLIGHT RISK AREA
MAY BE NEEDED ACROSS PARTS OF EAST AND NORTH TX ON FRIDAY/DAY 4 BUT
WILL WAIT UNTIL THE DAY 3 OUTLOOK IN ORDER TO GET A BETTER HANDLE ON
THE TIMING OF THE SYSTEM.

..BROYLES.. 01/31/2012

[WeatherMonger]

Day 2

DAY 2 CONVECTIVE OUTLOOK CORR 1
NWS STORM PREDICTION CENTER NORMAN OK
0247 AM CST TUE JAN 31 2012

VALID 011200Z - 021200Z

...NO SVR TSTM AREAS FORECAST...

CORRECTED TO COLOR-FILL THE PROBABILITY GRAPHIC

...ARKLATEX...
AN UPPER-LEVEL TROUGH WILL MOVE ACROSS THE SRN PLAINS WEDNESDAY AS A
40 TO 50 KT MID-LEVEL JET MOVES INTO THE ARKLATEX. AHEAD OF THE
SYSTEM...MODEL FORECASTS DEVELOP AN AXIS OF INSTABILITY FROM CNTRL
TX EXTENDING NEWD INTO SWRN AR WHERE THE MODELS DEVELOP SCATTERED
THUNDERSTORMS DURING THE AFTERNOON. FORECAST SOUNDINGS AROUND DALLAS
TX AT 21Z SHOW MUCAPE VALUES OF 500 TO 1000 J/KG WITH MID-LEVEL
LAPSE RATES AROUND 7.0 C/KM. THIS ALONG WITH 50 KT OF DEEP LAYER
SHEAR MAY BE ENOUGH FOR A MARGINAL HAIL THREAT AS THUNDERSTORMS
DEVELOP JUST AHEAD OF THE TROUGH AXIS AND MOVE INTO THE SRN OZARKS
WEDNESDAY EVENING. THE MAIN UNCERTAINTY FOR THE HAIL THREAT IS
CONVECTIVE COVERAGE. THE GFS DEVELOPS FEWER STORMS AND IS FURTHER TO
THE EAST. THE ECMWF IS FURTHER TO THE NORTH WHILE THE NAM DEVELOPS
STORMS BACK TO THE WEST AROUND THE DALLAS/FORT WORTH METROPLEX. HAVE
TAKEN A COMPROMISE BETWEEN THE THREE SOLUTIONS MAINTAINING A 5
PERCENT HAIL PROBABILITY FROM NEAR DALLAS ENEWD TO JUST NORTH OF
SHREVEPORT LA.

..BROYLES.. 01/31/2012

[WeatherMonger]

Day 3

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0229 AM CST TUE JAN 31 2012

VALID 021200Z - 031200Z

...THERE IS A SLGT RISK OF SVR TSTMS WCNTRL TX...

...SRN AND CNTRL PLAINS...
A SOMEWHAT FLATTENED UPPER-LEVEL TROUGH OVER THE GREAT PLAINS
WEDNESDAY NIGHT WILL MOVE EWD ACROSS THE MS VALLEY ON THURSDAY. ON
THE WRN SIDE OF THE RIDGE....MOISTURE ADVECTION WILL TAKE PLACE
ACROSS THE SRN PLAINS AS A 40 TO 50 KT LOW-LEVEL JET STRENGTHENS.
THUNDERSTORM DEVELOPMENT WILL BE POSSIBLE ALONG THE AXIS OF THE
LOW-LEVEL JET IN WEST TX THURSDAY AFTERNOON WITH CONVECTION RAPIDLY
EXPANDING NWD ACROSS NW TX AND WRN OK THURSDAY EVENING. FORECAST
SOUNDINGS THURSDAY EVENING ALONG THIS CORRIDOR FROM 00Z TO 06Z SHOW
MUCAPE VALUES AROUND 1000 J/KG WITH 40 TO 50 KT OF DEEP LAYER SHEAR.
THIS ALONG WITH STEEP MID-LEVEL LAPSE RATES SHOULD BE FAVORABLE FOR
A LARGE HAIL THREAT. A WIND DAMAGE THREAT COULD ALSO DEVELOP
ESPECIALLY IF SFC-BASED STORMS CAN INITIATE. HOWEVER...THE LOCATION
WITH THE GREATEST THREAT IS STILL QUESTIONABLE. THE NAM IS FOCUSING
THE MOST CONVECTION FURTHER TO THE NORTH ACROSS THE ERN TX
PANHANDLE...WRN OK AND SRN KS WHILE THE GFS AND ECMWF KEEP THE
DEVELOPMENT IN WEST AND NORTHWEST TX. AT THIS POINT...AM FAVORING
THE GFS AND ECMWF SOLUTIONS. AS THIS SCENARIO PLAYS OUT...THE SLIGHT
RISK AREA WILL LIKELY NEEDED TO BE MOVED OR CHANGED IN THE DAY 2
OUTLOOK.

..BROYLES.. 01/31/2012