Severe Thunderstorm Warning 110, NWS Aberdeen, SD

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
901 PM CDT MON AUG 5 2013

.UPDATE...
A COUPLE OF CLUSTERS OF THUNDERSTORMS HAVE DEVELOPED IN RESPONSE
TO A POTENT SHORTWAVE WORKING ACROSS MONTANA THIS EVENING. THE
FIRST CUSTER OF STORMS IS ACROSS NORTHWEST NORTH DAKOTA AND
ANOTHER LINE OF STORMS IS CURRENTLY SITUATED ACROSS NORTHWEST
SOUTH DAKOTA...TRACKING EAST SOUTHEAST. THE CURRENT TRACK AND
TIMING OF THESE STORMS WILL BRING PRECIPITATION INTO OUR FAR
NORTHWEST CWA IN AN HOUR OR SO...AND POTENTIALLY INTO THE KMBG AND
KPIR AREAS BY AROUND MIDNIGHT IF THE LINE HOLDS TOGETHER. RIGHT
NOW IT LOOKS LIKE THE STRONGEST STORMS /CURRENTLY PRODUCING SEVERE
WIND GUSTS/ WILL REMAIN WEST OF OUR CWA. ADJUSTED POPS TO REFLECT
THE CURRENT TIMING OF THE SHOWERS AND THUNDERSTORMS. OTHERWISE THE
FORECAST REMAINS ON TRACK TONIGHT.

&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT
A COUPLE SHORT WAVES WILL MOVE ACROSS THE REGION IN NORTHWEST FLOW
ALONG WITH A COUPLE SURFACE COOL FRONTS. FOR TONIGHT...THE FIRST
SHORT WAVE WAS SHOWN WELL BY SATELLITE AND RADAR IN SOUTHERN
CANADA MAKING ITS WAY TOWARDS THE SOUTHEAST. SHOWER AND
THUNDERSTORM DEVELOPMENT WAS ALREADY OCCURRING WITH THIS SYSTEM
IN CANADA AND MT LATE THIS AFTERNOON. WITH PLENTY OF MUCAPE AND
GOOD DEEP LAYER SHEAR ALONG WITH LIFT FROM THE SHORT WAVE AND
SURFACE COOL FRONT...EXPECT SHOWERS AND THUNDERSTORMS TO CONTINUE
TO DEVELOP AND MAY AFFECT THE WESTERN CWA BY LATE THIS EVENING.
THESE WILL MOVE SOUTHEAST ACROSS THE REST OF THE CWA THROUGH TUESDAY
MORNING. HAVE IN GOOD CHANCES AT THIS TIME FOR THE CWA STARTING
OUT WEST. ALSO...THE SLIGHT RISK OF SEVERE WEATHER HAS BEEN PUSHED
EASTWARD TO THE MISSOURI RIVER FOR TONIGHT. EXPECT NEW SHOWER/STORM
DEVELOPMENT AGAIN MAINLY EAST IN THE CWA ON TUESDAY AFTERNOON
MOVING EAST DURING THE EVENING. CANADIAN SURFACE HIGH PRESSURE
WILL PUSH IN BEHIND THIS BRINGING DRIER AIR...BELOW NORMAL
TEMPERATURES AND CLEAR TO PARTLY CLOUDY SKIES AGAIN FOR TUESDAY
NIGHT AND WEDNESDAY ACROSS THE CWA. THE MODELS THEN SHOW ANOTHER
SHORT WAVE TROUGH SLIDING INTO THE REGION FROM THE NORTHWEST
WEDNESDAY NIGHT BRINGING BACK CHANCES OF SHOWERS AND STORMS TO THE
CWA.

.LONG TERM...THURSDAY THROUGH MONDAY
THURSDAY STARTS OFF WITH A FRONTAL BOUNDARY DROPPING SOUTH ACROSS
THE REGION. MODELS AGREE FAIRLY WELL WITH THIS AND DECENT CHANCES
FOR SHOWERS AND STORMS LOOK TO ACCOMPANY THIS FRONT. 12Z RUNS OF
THE GFS AND EC SHOW SFC DEWPOINTS REACHING THE LOW TO MID 60S OVER
THE SOUTHEAST CWA BY AFTERNOON...WHICH IS WHEN THE FRONT COMES
THROUGH. MODELS ACTUALLY AGREE FAIRLY WELL WITH THE TIMING OF THIS
FRONT. THEREFORE...BEST CHANCES FOR CONVECTION LOOK TO BE OVER THE
EASTERN/SOUTHEASTERN CWA. SURFACE HIGH PRESSURE BUILDS IN FOR
FRIDAY AND FRIDAY NIGHT...PROVIDING FOR MOSTLY DRY CONDITIONS.
ALTHOUGH...GFS/EC ARE SHOWING A MID LEVEL IMPULSE CROSSING THE
DAKOTAS FRIDAY NIGHT...MAINLY AFFECTING WESTERN AND CENTRAL SOUTH
DAKOTA SO HAVE LEFT IN ALLBLEND POPS FOR THIS TIME FRAME.
DEPENDING ON THE SPEED OF THIS WAVE...COULD STILL BE DEALING WITH
THE AFFECTS OF THE SYSTEM ON SATURDAY AS WELL SO DID NOT STRAY TOO
FAR FROM ALLBLEND POPS ON SATURDAY. SUNDAY AND MONDAY SHOW LITTLE
MODEL AGREEMENT AS 12Z EC IS SHOWING SFC HIGH PRESSURE OVER THE
REGION BUT 12Z GFS REMAINS A BIT UNSETTLED. FOR NOW HAVE GONE WITH
DRY CONDITIONS UNTIL BETTER MODEL AGREEMENT IS REACHED.

&&

.AVIATION...
00Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

AN UPPER LEVEL DISTURBANCE IN COINCIDENCE WITH A SURFACE FRONTAL
BOUNDARY IS AIDING IN THUNDERSTORMS DEVELOPMENT ACROSS EASTERN
MONTANA AND WYOMING THIS EVENING. THESE STORMS ARE EXPECTED TO
MOVE EASTWARD THROUGH THE NIGHT...AND MAY BE ENHANCED BY A LOW
LEVEL JET NOSING INTO SOUTH CENTRAL SOUTH DAKOTA OVERNIGHT.
SHOWERS AND THUNDERSTORMS ARE ESTIMATED TO BE AROUND THE KMBG AND
KPIR TAFS SITES BY AROUND 06Z...AND VCTS ARE MENTIONED IN THE TAFS
FOR BOTH SITES. UNCERTAIN HOW FAR STORMS WILL PROPAGATE EAST...SO
DID NOT MENTION THUNDER IN THE KABR OR KATY TAF SITE AT THIS
TIME...BUT WILL MONITOR AND MAKE APPROPRIATE TAF AMENDMENTS AS THE
STORMS NEAR. ALSO...WINDS WILL GRADUALLY SHIFT AROUND TO THE WEST
AND THEN NORTHWEST BEHIND THE FRONT. THE WIND SWITCH WILL OCCUR BY
THE EARLY MORNING HOURS AT KMBG/KPIR AND WILL FOLLOW SUIT AT THE
KABR/KATY TAF SITES LATER IN THE DAY TUESDAY.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&

UPDATE...SERR
SHORT TERM...MOHR
LONG TERM...TMT
AVIATION...SERR

WEATHER.GOV/ABERDEEN

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