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 27 28
000
ACUS02 KWNS 231704
SWODY2
SPC AC 231703

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1203 PM CDT WED JUL 23 2014

VALID 241200Z - 251200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE NORTHERN
PLAINS...

...SUMMARY...
SEVERE STORMS ARE POSSIBLE OVER PARTS OF THE NORTHERN GREAT PLAINS
ON THURSDAY AFTERNOON AND EVENING...WITH ADDITIONAL STRONG TO
LOCALLY SEVERE STORMS SPREADING EASTWARD TOWARD MINNESOTA AND IOWA
OVERNIGHT. STRONG TO LOCALLY SEVERE STORMS ARE ALSO POSSIBLE FROM
SOUTHEAST VIRGINIA TO EASTERN GEORGIA.

...SYNOPSIS...

A POTENT SHORTWAVE TROUGH OVER SW CANADA AND THE PACIFIC NW WILL
PIVOT E/NE ON THURSDAY ACROSS THE NRN ROCKIES AND CANADIAN PRAIRIE
PROVINCES. THIS WILL SHUNT THE HIGH PLAINS UPPER RIDGE EWD TOWARD
THE UPPER MIDWEST...RESULTING IN HEIGHT FALLS AND A BAND OF ENHANCED
W/SWLY FLOW SPREADING ACROSS THE NRN PLAINS LATE THURSDAY AFTERNOON
INTO THE OVERNIGHT HOURS. AT THE SFC...A COLD FRONT WILL TRACK E/SE
ACROSS ERN MT/NE WY INTO THE WRN DAKOTAS DURING THE EVENING...AND
INTO THE ERN DAKOTAS BY 12Z FRIDAY.

FURTHER EAST...THE ERN CONUS TROUGH WILL BE MAINTAINED THROUGH THE
PERIOD WITH A WEAKENING SFC COLD FRONT TRACKING SWD FROM THE
SOUTHERN PLAINS THROUGH THE MID-SOUTH AND INTO THE CAROLINAS.

...NORTHERN PLAINS...

A CONDITIONAL SEVERE THREAT WILL EXIST DURING THE LATE
AFTERNOON/EARLY EVENING FROM FAR ERN MT INTO WRN ND AND POTENTIALLY
AS FAR SOUTH AS NW SD. WHILE SHEAR PROFILES WILL SUPPORT SUPERCELLS
AS THE COLD FRONT TRACKS EWD ACROSS THE AREA...VERY WARM MIDLEVEL
TEMPERATURES WILL BE HARD TO OVERCOME AS STRONGER HEIGHT FALLS AND
FORCING FOR ASCENT DO NOT APPEAR TO BE WELL TIMED WITH PEAK DIURNAL
HEATING. IF STORMS CAN DEVELOP ALONG/AHEAD OF THE FRONT IN THE WARM
SECTOR...MODERATE TO STRONG INSTABILITY WITH STEEP LAPSE RATES AND
FAVORABLE SHEAR PROFILES WILL FAVOR LARGE HAIL AND DAMAGING WINDS
ACROSS THE SLIGHT RISK AREA. AS THE RIDGE CONTINUES TO BREAK DOWN
OVERNIGHT...SEWD PROPAGATING STORM CLUSTER/MCS OVER NW ND AND SRN
SASKATCHEWAN MAY MOVE ACROSS PORTIONS OF CNTRL/ERN ND/SD...POSING
MAINLY A HAIL THREAT.

...SRN MN/IA...

VARIOUS MODEL GUIDANCE IS FAIRLY CONSISTENT IN BRINGING A SHORTWAVE
IMPULSE THROUGH THE UPPER RIDGE FROM THE CENTRAL ROCKIES ACROSS NEB
AND INTO MN/IA OVERNIGHT. AS THIS IMPULSE APPROACHES THE REGION...A
SWLY LLJ WILL INCREASE AND BECOME JUXTAPOSED WITH ENHANCED /40+ KT/
WLY 500 MB FLOW. THUNDERSTORMS CLUSTERS MAY GROW UPSCALE INTO A
S/SEWD PROPAGATING MCS OVERNIGHT IN MODERATE INSTABILITY AND STEEP
LAPSE RATE ENVIRONMENT. HOWEVER...ELEVATED NATURE OF THE STORMS
SHOULD LIMIT SEVERE POTENTIAL WITH THE GREATEST THREAT PROBABLY ONLY
MARGINALLY SEVERE HAIL AND HEAVY RAIN.

...SE VA INTO SE GA...

A BAND OF ENHANCED MIDLEVEL FLOW WILL BE IN PLACE ACROSS THE WARM
SECTOR EAST OF THE APPALACHIANS AND AHEAD OF THE SFC COLD FRONT. MID
60S+ SFC DEWPOINTS AND TEMPERATURES IN THE MID 80S TO NEAR 90 WILL
RESULT IN MODERATE INSTABILITY BY AFTERNOON. THUNDERSTORMS SHOULD
DEVELOP AHEAD OF THE COLD FRONT AND MAY TRY TO BECOME SEMI-ORGANIZED
ALONG ANY OUTFLOW BOUNDARIES AND SEA BREEZE INTERACTIONS. POOR
MIDLEVEL LAPSE RATES AND WEAK LOW LEVEL FLOW SHOULD GENERALLY LIMIT
ORGANIZATION/LONGEVITY OF ANY SEVERE THREAT...BUT A FEW
STRONG/LOCALLY DAMAGING WIND GUSTS ARE POSSIBLE.

..LEITMAN.. 07/23/2014



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