Special Weather Briefing:Special Weather Briefing:IsaacIsaac

08/29/201208/29/2012

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

Brandi RichardsonBrandi RichardsonMeteorologistMeteorologist

National Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana

Isaac Summary Uncertainty Uncertainty Official Isaac ForecastOfficial Isaac Forecast

Even further westEven further west Slowed movementSlowed movement Higher risk for heavy rainfallHigher risk for heavy rainfall

Model DataModel Data Several models still on a more westward trackSeveral models still on a more westward track Largest impacts over N LA/S AR, but impacts into E Largest impacts over N LA/S AR, but impacts into E

TX/SE OKTX/SE OK

National Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana

Current PositionCurrent PositionH

Radar ImageryRadar Imagery

Official NHC Track ForecastOfficial NHC Track Forecast

Tuesday morning

Latest trackforecast(shiftedwest)

Official Rainfall ForecastOfficial Rainfall Forecast

Locally higher totals may be possible

4-7”2-4”

1-2”

Official Forecast Official Forecast Impacts: Impacts: FloodingFlooding

N LAN LA Greatest risk for Greatest risk for

floodingflooding Wed PM-Fri AMWed PM-Fri AM

S ARS AR 22ndnd greatest risk area greatest risk area Early Thu AM-Fri PMEarly Thu AM-Fri PM

Extreme E TXExtreme E TX Wed PM-Fri AMWed PM-Fri AM Elevated risk Elevated risk

Flash

Flo

oding

Flash

Flo

oding

Possib

le

Possib

le

Official Forecast Official Forecast Impacts: Impacts: WindsWinds

9 PM Wed9 PM Wed

7 AM Thu7 AM Thu

Tropical Tropical Storm force Storm force

windswinds

N Central LA N Central LA ~40-45 mph~40-45 mph Wed night-most of Wed night-most of

Thu Thu

SW AR/SE OK SW AR/SE OK 15-20 mph15-20 mph ThuThu

Deep E TXDeep E TX 20-25 mph 20-25 mph Late Wed PM – Late Wed PM –

most of Thumost of Thu

E TX E TX 10-15 mph10-15 mph ThuThu

Official Forecast Official Forecast Impacts: Impacts: TornadoesTornadoes

Thu AM – Fri AM

N Central N Central LA/S AR LA/S AR Most at riskMost at risk Quick spin-Quick spin-

upsups Not much Not much

lead timelead time

ElsewhereElsewhere Can’t rule it Can’t rule it

out, but very out, but very low risklow risk

Watches/Warnings/Watches/Warnings/AdvisoriesAdvisories

Flash Flood Watch

7 AM Thu - 7 PM Thu

Topical Storm

WarningFlash Flood

Watch7 PM Wed - 1 PM Thu

UncertaintyUncertainty

Westward PotentialWestward Potential

Westward Case RainfallWestward Case Rainfall

Through Saturday morning

6-8”

2-4”4-6”

Potential ImpactsPotential Impacts More westward track:More westward track:

N LA/S AR N LA/S AR Heavy rainfall/flooding (5-10”) Heavy rainfall/flooding (5-10”) Greatest impact timeframe: Thu/Thu PMGreatest impact timeframe: Thu/Thu PM Winds 40-45 mph with higher gusts Wed PM-Thu Winds 40-45 mph with higher gusts Wed PM-Thu

PM for N/LA; ~25 mph with higher gusts for S ARPM for N/LA; ~25 mph with higher gusts for S AR Prime tornado threat areaPrime tornado threat area

E TX/SE OKE TX/SE OK Rainfall: 2-4” isolated 5”Rainfall: 2-4” isolated 5” Winds 25-35 mph with higher gusts Thu AM-Thu Winds 25-35 mph with higher gusts Thu AM-Thu

PMPM Tornado threat along eastern-tier counties in E TXTornado threat along eastern-tier counties in E TX

Official NHC Track ForecastOfficial NHC Track Forecast

NEXT CONFERENCE CALL:

Today August 29, 2012 @ 5:30 PMToday August 29, 2012 @ 5:30 PM

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

National Weather Service Shreveport, LouisianaNational Weather Service Shreveport, Louisiana