Severe Weather Severe Weather BriefingBriefing

11/08/201111/08/2011

www.srh.noaa.gov/shv/briefingwww.srh.noaa.gov/shv/briefing

Keith StellmanKeith StellmanWarning Coordination Warning Coordination

MeteorologistMeteorologistNational Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana

OverviewThis afternoon through tonight:This afternoon through tonight:

Setup:Setup: Strong upper level system passing to the Strong upper level system passing to the

northwest of the regionnorthwest of the region Strong coupled jet streamStrong coupled jet stream Cold front moving in from the westCold front moving in from the west Ample wind shear for rotating stormsAmple wind shear for rotating storms

ImpactsImpacts Damaging windsDamaging winds A few tornadoes possibleA few tornadoes possible Heavy RainHeavy Rain

Hail a lesser threatHail a lesser threatNational Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana

CurrentlyCurrently

National Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana

LArea of focus

Radar @ 930Radar @ 930 Some Some

warnings warnings for north for north endend

Expect Expect lower end lower end to fill as to fill as day day progressesprogresses

Current InstabilityCurrent Instability Best area Best area

(Pink) just (Pink) just west of the west of the regionregion

Dashed blue Dashed blue lines is CAP lines is CAP strength… strength… stronger stronger easteast

Forecast Instability @ Noon Forecast Instability @ Noon (GFS)(GFS)

Best area Best area (Pink->Red) (Pink->Red) I-49 and westI-49 and west

Peaks of near Peaks of near 2000 J/KG 2000 J/KG (double what (double what is needed is needed across Deep across Deep East TXEast TX

Low level wind shear (0-1 Low level wind shear (0-1 KM) KM) (noon)(noon)

Lowest Lowest level wind level wind shear… shear… used for used for TornadoTornado

Values >90 Values >90 needed.needed.

Values Values peak over peak over 200 (white)200 (white)

Upper level Jet (250 Upper level Jet (250 mb)mb)

Note the divergent

winds

2 Jet streaks working east…

putting us in the favorable region

SPC slight r

isk area

SPC slight r

isk area

TornadoTornado- - Best support (proximity to Best support (proximity to surface low NE TX, SE OK, SW surface low NE TX, SE OK, SW ARAR- Best instability and sufficient - Best instability and sufficient shear located across Deep East shear located across Deep East TX -> NW LATX -> NW LA

• A few Tornadoes A few Tornadoes possiblepossible• Most likely Most likely embedded within embedded within the line that the line that developsdevelops•Most likely rain Most likely rain wrappedwrapped

Area

we nee

d to

wat

ch

Area

we nee

d to

wat

ch

WindWindDamaging Winds along a Damaging Winds along a

squall linesquall lineLook for bows in the line Look for bows in the line

NoonNoon Activity Activity

beginning beginning across the across the East TX/ SE East TX/ SE OK and OK and portions portions of of SW ARSW AR

Front Front approachingapproaching

L

6 PM6 PM Heavy Rain Heavy Rain

bisecting the bisecting the regionregion

Front Front ~LA/TX line~LA/TX line

L

MidnightMidnight Heavy rain Heavy rain

ending ending across the across the NE LA/ NE LA/ South ARSouth AR

Front Front ~Monroe - ~Monroe - >Jena>Jena

L

Computer Model Rainfall Computer Model Rainfall Forecast Forecast (GFS)(GFS) Swath of 2 Swath of 2

+ + extending extending from from Lufkin -> Lufkin -> Shreveport Shreveport -> Homer-> Homer

Due to Due to added added instability instability and added and added lift from lift from jet jet

1.50

” – 2”

1.0

0”

- 1.5

0”

1.0

0”

– 1.5

0”

Rainfall Forecast (Late Monday ->

Early Wed)Some isolated totals near 3” are possible from East TX -> North LA/South AR.

1.50

” – 2”

Summary

This afternoon into tonight:This afternoon into tonight: Greatest risk area from SE OK/SW AR - > Greatest risk area from SE OK/SW AR - >

East TXEast TX Greatest threats for tonight:Greatest threats for tonight:

Damaging WindsDamaging Winds Isolated tornadoesIsolated tornadoes Heavy RainHeavy Rain

Some uncertainty exists with just how far Some uncertainty exists with just how far south storms initiate in East Texas. south storms initiate in East Texas. However, best instability lies there and However, best instability lies there and will need to be watched. will need to be watched.

National Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana

NEXT CONFERENCE CALL:

Thursday 11/10 @ 10 AMThursday 11/10 @ 10 AM

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National Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana