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 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
932
ACUS01 KWNS 131939
SWODY1
SPC AC 131937

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0137 PM CST SAT FEB 13 2016

VALID 132000Z - 141200Z

...NO SVR TSTM AREAS FORECAST...

...SUMMARY...
SOME THUNDERSTORM ACTIVITY STILL APPEARS POSSIBLE ACROSS AND
SOUTHEAST OF THE BIGHORN BASIN AND MOUNTAINS THIS AFTERNOON INTO
EARLY EVENING.

...20Z OUTLOOK UPDATE...
ANY APPRECIABLE RISK FOR THUNDERSTORM ACTIVITY LATE THIS AFTERNOON
AND EVENING NOW APPEARS LARGELY CONFINED TO AREAS OF WYOMING ACROSS
AND SOUTHEAST OF THE BIGHORN BASIN AND MOUNTAINS.  THIS IS WHERE
SURFACE TEMPERATURES HAVE WARMED INTO THE 40S AND 50S...AND
LOW-LEVEL LAPSE RATES HAVE BECOME QUITE STEEP WITH BOUNDARY LAYER
HEATING AND MIXING.

LIGHTNING HAS RECENTLY BEEN DETECTED WITH CONVECTION OVER THE
MOUNTAINS TO THE NORTH AND WEST OF CODY WY...LIKELY AIDED BY FORCING
FOR ASCENT IN THE EXIT REGION OF A DIGGING MID-LEVEL JET STREAK
/PERHAPS INTENSIFYING TO 80-90+ KT AT 500 MB/.  AS THIS FORCING
SPREADS SOUTHEASTWARD LATE THIS AFTERNOON...AN ADDITIONAL STORM OR
TWO APPEARS POSSIBLE ACROSS AND JUST SOUTH OF THE BIGHORN BASIN.

THE BEST CHANCE FOR THUNDERSTORMS THIS AFTERNOON...HOWEVER...SEEMS
TO EXIST NEAR AND NORTH THROUGH WEST/SOUTHWEST OF GILLETTE...WHERE
WEAK BOUNDARY LAYER DESTABILIZATION HAS BECOME MOST APPARENT...ALONG
AND TO THE EAST OF THE BIGHORN MOUNTAINS.

..KERR.. 02/13/2016

.PREV DISCUSSION... /ISSUED 1012 AM CST SAT FEB 13 2016/

...SYNOPTIC SETUP...
LARGE-SCALE PATTERN WILL SOMEWHAT DEAMPLIFY THROUGH SUN AS LAST
SIGNIFICANT SHORTWAVE IMPULSE ROUNDS BASE OF ERN U.S TROUGH AND FLAT
RIDGE PROGRESSES FROM THE RCKYS INTO THE PLNS/MS VLY. UPSTREAM
SHORTWAVE DISTURBANCE NOW OVER ID SHOULD FURTHER DEVOLVE AS IT
SHEARS ESE ACROSS THE NRN HIGH PLNS THIS EVE...AND REACHES SW MN/WRN
IA EARLY SUN.

ARCTIC SFC HIGH WILL CONTINUE SLOWLY E FROM THE MS VLY INTO THE
APPALACHIANS...WHILE INCREASING WLY FLOW ALOFT AND DYNAMIC SUPPORT
ENCOURAGE FURTHER LEE TROUGHING OVER THE NRN HIGH PLNS. THE TROUGH
SHOULD PROGRESS E/SE INTO CNTRL PORTIONS OF THE DAKOTAS AND NEB BY
12Z SUN...BUT LIKELY WITHOUT ASSUMING A SIGNIFICANT BAROCLINIC
NATURE.

...NRN HIGH PLNS THIS AFTN/EVE...
DOWNSLOPE FLOW AND SFC HEATING IN WAKE OF DEPARTING HIGH-LVL
CONVEYOR BELT CLOUD BAND WILL YIELD SEASONABLY WARM CONDITIONS FROM
SRN MT SEWD INTO THE BLACK HILLS LATER TODAY. AT THE SAME
TIME...MID-LVL LAPSE RATES AND ASCENT WILL INCREASE OVER REGION WITH
THE CONTINUED ESE MOVEMENT OF ID UPR IMPULSE. THE LEADING EDGE OF
THIS DESTABILIZATION/FORCING IS NOW OVER SW MT AND SHOULD REACH SE
MT/NE WY BY MID-LATE AFTN. COUPLED WITH LOW-LVL UPLIFT ALONG LEE
TROUGH...SETUP MAY PROMOTE DEVELOPMENT OF SCTD BOUNDARY-LAYER BASED
CONVECTION SUFFICIENTLY DEEP TO YIELD OCCASIONAL THUNDER. GIVEN 40+
KT UNIDIRECTIONAL WNW FLOW LIKELY TO BE PRESENT AT THE TOP OF THE
MIXED LAYER...POTENTIAL WILL EXIST FOR CONVECTIVELY ENHANCED SFC
GUSTS. SUSTAINED/ORGANIZED SVR GUSTS ARE...HOWEVER...NOT EXPECTED.

$$



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