Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS03 KWNS 190727
SWODY3
SPC AC 190725

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0225 AM CDT SUN APR 19 2015

VALID 211200Z - 221200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN HIGH
PLAINS...

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
PLAINS...

...SUMMARY...
THUNDERSTORM DEVELOPMENT IS EXPECTED TO TAKE PLACE LATE TUESDAY
AFTERNOON ACROSS THE SOUTHERN PLAINS WHERE LARGE HAIL AND WIND
DAMAGE WILL BE POSSIBLE. THUNDERSTORMS MAY ALSO FORM OVER PARTS OF
THE SOUTHERN AND CENTRAL ROCKIES...SOUTHERN GREAT
LAKES...SOUTH-CENTRAL FLORIDA PENINSULA AND IN THE SIERRA NEVADA.

...SRN PLAINS...
A BROAD CYCLONIC FLOW PATTERN IS FORECAST ACROSS THE ERN HALF OF THE
NATION ON TUESDAY AS AN UPPER-LEVEL RIDGE MOVES SLOWLY ACROSS THE
SRN ROCKIES AND GREAT BASIN. AT THE SFC...A LOW IS FORECAST TO MOVE
EWD INTO THE SRN HIGH PLAINS WITH A DRYLINE SETTING UP ACROSS WEST
TX. SLY LOW-LEVEL WINDS TO THE EAST OF THE DRYLINE SHOULD RESULT IN
MOISTURE ADVECTION THROUGHOUT THE PERIOD.  MODEL SOLUTIONS VARY ON
HOW MUCH MOISTURE WILL RETURN NWD. THE NAM AND GFS SOLUTIONS SUGGEST
THAT SFC DEWPOINTS WILL REACH THE LOWER 60S F IN THE TX HILL COUNTRY
AND WEST TX WITH MID TO UPPER 50S F POSSIBLY IN THE LOW ROLLING
PLAINS AND ON THE CAPROCK. BOTH THE NAM AND GFS SOLUTIONS DEVELOP
CONVECTION ALONG AN AXIS OF INSTABILITY FROM THE ERN TX PANHANDLE
SEWD INTO NW TX LATE TUESDAY AFTERNOON. GFS FORECAST SOUNDINGS AT
00Z/WEDNESDAY SHOW POCKETS OF MODERATE INSTABILITY IN PLACE WITH
ABOUT 40 KT OF DEEP-LAYER SHEAR OWING TO DIRECTIONAL SHEAR BELOW 700
MB AND 50 KT OF FLOW ALOFT. THIS COMBINED WITH STEEP LAPSE RATES
WOULD SUPPORT SUPERCELLS WITH LARGE HAIL. ISOLATED WIND DAMAGE WOULD
ALSO BE POSSIBLE. ALTHOUGH THE MODELS ARE SOMEWHAT IN AGREEMENT
CONCERNING CONVECTIVE INITIATION ON THE CAPROCK AND OVER THE LOW
ROLLING PLAINS...THE EXTENDED FORECAST RANGE INTRODUCES MUCH
UNCERTAINTY. THE UPPER-LEVEL RIDGE COULD HELP TO INHIBIT STORM
DEVELOPMENT KEEPING CONVECTIVE COVERAGE ISOLATED ACROSS THE REGION.
ATTM...WILL INTRODUCE A SMALL SLIGHT RISK AREA ACROSS PARTS OF NW
TX...THE SE TX PANHANDLE AND SW OK WHERE THE POTENTIAL FOR SEVERE
STORMS APPEARS THE GREATEST.

..BROYLES.. 04/19/2015



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