Virtual Chase Slight Risk Sthrn Gulf States And Sthrn Plains Thurs 26th

[Tony Gilbert]

Could be some underestimation for tornado genesis SE OK and NE TX by late afternoon and early evening IMO.

Heavy capping south of the stationary cold front insulates a continued warm moist surface feed up toward Oklahoma. Cap is expected to erode as a result of this advection. Cold upper pooling aloft stretches south ready to rapidly increase lapse rates around any cell that breaks through the cap. Net result could be quite explosive on a local scale. SPC are going for the risk of very big hail. Earlier concerns regarding the development of surface based storms seems less like a problem now. Certainly one to watch for over the next few hrs. I would put isolated tornado risk within the said zone at about 15 %. But then of course we can never really be certain. Though my overal opinion based on the RUC model would suggest the potential risk of some very powerful storm between 21Z-03Z

Edited March 26, 2009 by Tony Gilbert

[NL]

SPC have been monitoring this potential and at the moment they feel a severe watch will be unlikely.

MESOSCALE DISCUSSION 0276

NWS STORM PREDICTION CENTER NORMAN OK

1254 PM CDT THU MAR 26 2009

AREAS AFFECTED...NERN OK...SERN KS...SW MO...NWRN AR

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 261754Z - 262000Z

ISOLATED SEVERE HAIL REPORTS...GENERALLY OF 1" OR LESS IN

DIAMETER...ARE EXPECTED. A WW IS NOT LIKELY.

A CLUSTER OF ELEVATED THUNDERSTORMS HAS FORMED ON THE NOSE OF AN 850

JET WHERE WARM/MOIST ADVECTION WAS OCCURRING. ALTHOUGH INSTABILITY

IS NOT HIGH...PRESENCE OF STEEP MID LEVEL LAPSE RATES WITH 500 MB

TEMPS COOLER THAN -20 C SUGGEST THE FORMATION OF HAIL WILL EASILY

OCCUR. ENOUGH DEEP SHEAR IN THE CLOUD BEARING LAYER FURTHER SUGGESTS

A FEW OF THE STRONGER CORES MAY PERSIST FOR SEVERAL COUNTIES WITH A

THREAT OF SOME HAIL.

They've just removed the above MD.

Tomorrow is still (although doubts were raised yesterday) looking on for a severe outbreak with the SPC upgrading to moderate

http://www.spc.noaa.gov/products/outlook/day2otlk.html

[NL]

Severe potential along the Texan coast into Louisiana.

MESOSCALE DISCUSSION 0277

NWS STORM PREDICTION CENTER NORMAN OK

0306 PM CDT THU MAR 26 2009

AREAS AFFECTED...SERN TX...SRN LA

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 262006Z - 262100Z

REMNANTS OF UPPER VORT/SHORTWAVE TROUGH ARE SHEARING EWD ACROSS

SCNTRL TX TOWARD THE UPPER TX COAST. THIS FEATURE APPEARS TO BE

PARTLY RESPONSIBLE FOR RETURN OF MARITIME BOUNDARY LAYER AIRMASS NWD

ACROSS THE UPPER TX COAST AND SRN LA WHERE SFC DEW POINTS ARE NEAR

70F. WEAK WARM ADVECTION PERSISTS ACROSS THIS REGION WHICH COMBINED

WITH ASCENT AHEAD OF UPPER VORT IS ENHANCING RASH OF NEW CONVECTION

ACROSS SERN TX. GIVEN THE STRONG DEEP LAYER SHEAR AND MLCAPE ON THE

ORDER OF 2000 J/KG...SUPERCELL DEVELOPMENT IS CERTAINLY POSSIBLE.

WW WILL LIKELY BE ISSUED TO ADDRESS THIS ACTIVITY WITHIN THE NEXT

HOUR.

[Tony Gilbert]

Yes, some back tracking by the RUC since the last model output with a stronger cap evident over suggested region. Potential seems rather less now than earlier thinking. It is quite likely that the storms across the risk zone will in fact continue to develop from above the boundary layer . In which case tornadoes would then become fairly unlikely for that region.

Edited March 26, 2009 by Tony Gilbert

[NL]

Well i think that MD that was withdrawn earlier was a bit short-coming as a tornado warning has been issued for N/central Texas.

BULLETIN - EAS ACTIVATION REQUESTED

TORNADO WARNING

NATIONAL WEATHER SERVICE FORT WORTH TX

829 PM CDT THU MAR 26 2009

THE NATIONAL WEATHER SERVICE IN FORT WORTH HAS ISSUED A

* TORNADO WARNING FOR...

COOKE COUNTY IN NORTH CENTRAL TEXAS...

* UNTIL 930 PM CDT

* AT 828 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A

DEVELOPING TORNADO 5 MILES NORTHWEST OF MUENSTER...MOVING EAST AT

20 MPH. ANOTHER SEVERE THUNDERSTORM CAPABLE OF PRODUCING A

TORNADO IS LOCATED JUST NORTH OF GAINESVILLE. THIS STORM IS ALSO

MOVING EAST AT 20 MPH. THESE STORMS HAVE HAD A HISTORY OF

PRODUCING OF LARGE DAMAGING HAIL. IN ADDITION TO

TORNADOES...LARGE HAIL TO NEAR BASEBALL SIZE IS LIKELY.

* THE TORNADO WILL BE NEAR...

MUENSTER BY 840 PM CDT...

LINDSAY BY 905 PM CDT...

Looks very ominous..!!

Even more so now ....a very distinctive hook, thats looking like a monster.!!!

[Tony Gilbert]

Hi NL, yes 3 brief touch downs recorded by SPC for that cell within the earlier region of interest.

PS. Just to say how much I agree with your footnotes on common misconceptions at the bottom of your posts!

[NL]

G'morning Tony, i was half expecting headlines to read EF3-4 smashes through N/Texas with some of the sat/infa-red images last night as they looked very impressive, if that scenario happened a little earlier i think it could have been a lot worse for the northern counties of Texas.. very complicated this morning with several convective scenarios , forecasters nightmare.!! I'm hoping the messy MCS from overnight clear quickly allowing diurnal heating and kickstart those storms ,today could be quite an outbreak if certain parameters fall into place.