Severe Storm Outlook Narrative (AC)
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
000
ACUS02 KWNS 221710
SWODY2
SPC AC 221709

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1209 PM CDT TUE JUL 22 2014

VALID 231200Z - 241200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE NRN
ROCKIES...

...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN WY INTO WRN SD AND THE
NEB PANHANDLE...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS MUCH OF NEW ENGLAND...

...SUMMARY...
SEVERE STORMS ARE POSSIBLE ACROSS PARTS OF THE NORTHERN ROCKIES FROM
NORTHERN IDAHO INTO WESTERN AND CENTRAL MONTANA AS WELL AS ACROSS
NEW ENGLAND WEDNESDAY AFTERNOON AND EVENING. ADDITIONAL SEVERE
THUNDERSTORMS ARE POSSIBLE FROM EASTERN WYOMING INTO WESTERN SOUTH
DAKOTA AND NEBRASKA LATE IN THE AFTERNOON INTO WEDNESDAY NIGHT.
ELSEWHERE...STRONG TO LOCALLY SEVERE STORMS ARE POSSIBLE OVER THE
NORTHERN HIGH PLAINS AND FROM THE OHIO VALLEY TO THE OZARKS AREA.

...SYNOPSIS...

THE UPPER RIDGE SPREADING NORTHWARD FROM THE CNTRL/SRN ROCKIES INTO
THE NRN HIGH PLAINS WILL SHIFT SLIGHTLY EWD WHILE MARGINALLY
DEAMPLIFYING AS THE PACIFIC NORTHWEST SHORTWAVE TROUGH MOVES INLAND.
AT THE SFC...A LEE TROUGH WILL EXTEND SWD FROM A WEAK SFC LOW OVER
S-CNTRL MT ACROSS ERN WY INTO NE CO. FURTHER EAST...A TROUGH OVER SE
CANADA AND THE GREAT LAKES WILL DEEPEN ALONG THE APPALACHIANS WHILE
A SFC COLD FRONT TRACK E/SE FROM NEW ENGLAND INTO THE OH/TN VALLEYS
AND SOUTHERN PLAINS.

...NRN ROCKIES...

ENHANCED S/SWLY FLOW WILL OVERSPREAD THE NRN ROCKIES AS INTENSE
SHORTWAVE TROUGH MOVES INLAND THROUGH THE FORECAST PERIOD. THE
RESULTING FALLING HEIGHTS/COOLING ALOFT WILL AID IN SCATTERED
THUNDERSTORM DEVELOPMENT DURING THE AFTERNOON AND EVENING AHEAD OF
AN EWD ADVANCING SFC COLD FRONT FROM FAR ERN WA INTO WRN/CNTRL MT.
S/SELY LOW LEVEL WINDS WILL MAINTAIN UPPER 40S/LOWER 50S DEWPOINTS.
AS TEMPERATURES WARM INTO THE 80S...WEAK TO MODERATE INSTABILITY
WILL DEVELOP BENEATH STEEP LAPSE RATES. INVERTED-V THERMODYNAMIC
PROFILES COUPLED WITH FAST STORM MOTION WILL FURTHER ENHANCE STRONG
WIND THREAT. SOME INSTANCES OF LARGE HAIL WILL BE POSSIBLE AS WELL.

...NRN HIGH PLAINS/BLACK HILLS...

ISOLATED TO SCATTERED THUNDERSTORM DEVELOPMENT IS EXPECTED NEAR
HIGHER TERRAIN ALONG THE LEE TROUGH BY MID/LATE AFTERNOON AND WILL
SPREAD EWD ACROSS THE HIGH PLAINS AS A SHORTWAVE IMPULSE MIGRATES
AROUND THE UPPER ANTICYCLONE FROM THE GREAT BASIN THROUGH THE CNTRL
ROCKIES OF WY. S/SELY LOW LEVEL FLOW WILL MAINTAIN MID 50S TO LOW
60S DEWPOINTS TO THE EAST OF THE LEE TROUGH AND AS TEMPERATURES WARM
INTO THE 90S...MODERATE TO STRONG INSTABILITY WILL DEVELOP BENEATH
STEEP LAPSE RATES. LARGE HAIL AND STRONG WINDS WILL BE THE MAIN
THREATS. LATER DURING THE EVENING/OVERNIGHT...WAA REGIME SHOULD
RESULT IN AN ARC OF THUNDERSTORMS FROM ERN MT INTO THE CNTRL
DAKOTAS. THE ELEVATED NATURE OF THIS CONVECTION SHOULD LIMIT
DAMAGING WIND THREAT...BUT SOME MARGINALLY SEVERE HAIL WILL BE
POSSIBLE.

...NEW ENGLAND...

HEIGHT FALLS/COOLING ALOFT ASSOCIATED WITH DEEPENING TROUGH OVER THE
REGION WILL AID IN THUNDERSTORM DEVELOPMENT BY LATE MORNING/EARLY
AFTERNOON AHEAD OF AN EWD ADVANCING COLD FRONT. A MOIST AIRMASS WITH
SFC DEWPOINTS IN THE MID/UPPER 60S WILL BE PRESENT WITH TEMPERATURES
WARMING INTO THE 80S TO NEAR 90 DEGREES...RESULTING IN MODERATE
DESTABILIZATION. MIDLEVEL LAPSE RATES WILL GENERALLY BE POOR...BUT
NEAR 30 KT DEEP LAYER SHEAR AND STEEP LOW LEVEL LAPSE RATES SHOULD
RESULT IN A STRONG/LOCALLY DAMAGING WIND THREAT. MARGINALLY SEVERE
HAIL MAY BE POSSIBLE AS WELL GIVEN DEGREE OF INSTABILITY.

...OH/TN VALLEY INTO CNTRL APPALACHIANS...

A WARM/MOIST AIRMASS CHARACTERIZED BY MID 60S TO NEAR 70 DEWPOINTS
AND HIGH TEMPERATURES NEAR 90 DEGREES WILL BE IN PLACE...WITH STEEP
LOW LEVEL LAPSE RATES DEVELOPING BY LATE MORNING/EARLY AFTERNOON. AS
A RESULT...STRONG INSTABILITY WILL BE PRESENT AND SCATTERED
THUNDERSTORMS ARE EXPECTED AHEAD OF THE COLD FRONT. HOWEVER...THREAT
SHOULD REMAIN RELATIVELY UNORGANIZED AS DEEP LAYER SHEAR WILL BE
WEAKER THAN THAT EXPECTED FURTHER TO THE NE ACROSS NEW ENGLAND.
ADDITIONALLY...STRONGER FORCING FOR ASCENT WILL NOT BE TIMED WELL
WITH DIURNAL PEAK HEATING FURTHER SE ACROSS THE CNTRL
APPALACHIANS...ARRIVING LATER DURING THE OVERNIGHT PERIOD. AS
SUCH...MARGINAL WIND/HAIL THREAT WILL EXIST DURING THE AFTERNOON
WITH PERHAPS A LOCALLY SEVERE STORM POSSIBLE.

...OZARKS...

ISOLATED THUNDERSTORMS ARE EXPECTED TO DEVELOP IN THE VICINITY OF
THE COLD FRONT FROM SRN MO INTO FAR ERN OK EWD ACROSS AR IN A
WARM/MOIST AND STRONGLY UNSTABLE ENVIRONMENT. THIS AREA WILL BE ON
THE PERIPHERY OF BAND OF STRONGER FLOW ALOFT BETWEEN THE RIDGE TO
THE WEST AND TROUGH TO THE EAST...RESULTING IN 20-30 KT 0-6 KM
SHEAR. FORCING FOR ASCENT WILL REMAIN WEAK...LIMITING OPPORTUNITY
FOR A BETTER ORGANIZED THREAT. A MARGINAL WIND THREAT /PERHAPS A FEW
LOCALLY DAMAGING GUSTS/ WILL EXIST WITH STRONGER STORM CLUSTERS AS
THEY TRACK SWD ACROSS THE REGION.

..LEITMAN.. 07/22/2014



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.