Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 050228
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
928 PM CDT TUE AUG 4 2015

.UPDATE...
ISSUED AT 900 PM CDT TUE AUG 4 2015

LATEST RADAR AND SATELLITE ANALYSIS SHOWS SHOWERS AND SCATTERED
THUNDERSTORMS OVER THE FAR SOUTHWEST PORTION OF THE STATE...MOVING
SLOWLY NORTH AND EAST. STILL AN AREA OF INSTABILITY OVER THE FAR
SOUTHWEST...AND STORMS HAVE RECENTLY . CAN NOT RULE OUT AN
ISOLATED SEVERE STORM...BUT LOWER ATMOSPHERE TO CONTINUE TO
STABILIZE...REDUCING THE THREAT AS WE HEAD INTO THE LATE EVENING.

MADE SOME ADJUSTMENTS TO POPS BASED ON THE LATEST ITERATIONS OF
THE RAP/HRRR THROUGH THE NIGHT.

UPDATE ISSUED AT 617 PM CDT TUE AUG 4 2015

SHOWERS AND THUNDERSTORMS CONTINUE ACROSS EASTERN MONTANA INTO
NORTHEAST WYOMING. CURRENT MOVEMENT IS GENERALLY NORTH. THUS HAVE
PUSHED BACK THE ARRIVAL TIME OF CONVECTION MOVING INTO WESTERN
NORTH DAKOTA UNTIL AROUND 01-04 UTC...AND SLOWED THE EASTWARD
PROGRESSION THROUGH 06Z...SIMILAR TO THE LATEST ITERATIONS OF THE
HRRR AND RAP. OTHERWISE NO SIGNIFICANT UPDATES OTHER THAN
POPULATING LATEST SENSIBLE WEATHER ELEMENTS.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 221 PM CDT TUE AUG 4 2015

THUNDERSTORM POTENTIAL TONIGHT INTO WEDNESDAY HIGHLIGHTS THE SHORT
TERM.

THE 12 UTC GLOBAL AND HIGH RESOLUTION SUITES CONTINUE TO SLOW THE
PROPAGATION AND WEAKEN THE OVERALL STRENGTH OF CONVECTION THAT IS
EXPECTED TO ENTER WESTERN NORTH DAKOTA THIS EVENING. THE 16-18 UTC
HRRR ITERATIONS ARE EVEN MORE PESSIMISTIC ABOUT THUNDERSTORMS
ENTERING WESTERN NORTH DAKOTA. THUS...HAVE REMOVED POPS FOR THIS
AFTERNOON FAR WEST...AND DECREASED THEM OVERNIGHT WITH 06 UTC
APPEARING TO BE THE BEST TIMEFRAME FOR POTENTIAL STORMS TO ENTER
THE WEST AS MOISTURE RETURN INTO EASTERN MONTANA HAS BEEN SLOW TO
DEVELOP SO FAR TODAY.

THE FOCUS FOR THUNDERSTORMS ON WEDNESDAY WILL BE ACROSS CENTRAL
NORTH DAKOTA AHEAD OF THE RIDGE RUNNING SHORTWAVE. SPC HAS
CENTRAL NORTH DAKOTA IN A MARGINAL RISK FOR SEVERE STORMS
WEDNESDAY AFTERNOON. OVERALL...EXPECTING 1500-2000 J/KG OF ML CAPE
WITH 30-35 KTS OF DEEP LAYER SHEAR TO DEVELOP THROUGH THE
AFTERNOON WITH SURFACE DEWPOINTS IN THE MID TO UPPER 60S.
ALTHOUGH...CLOUD COVER FROM ONGOING OVERNIGHT AND MORNING
CONVECTION DOES PLACE UNCERTAINTY ON HOW MUCH SURFACE
DESTABILIZATION MAY BE REALIZED.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 221 PM CDT TUE AUG 4 2015

PERIODIC CHANCES FOR SHOWERS AND THUNDERSTORMS CONTINUE TO HIGHLIGHT
THE WEDNESDAY NIGHT THROUGH SUNDAY TIME PERIOD...FOLLOWED BY A TREND
OF MAINLY DRY AND WARMER CONDITIONS MONDAY AND TUESDAY.

THE LATEST WATER VAPOR IMAGERY SHOWS A SHORTWAVE TROUGH LOCATED NEAR
-126/36...WHICH IS JUST OFF THE CALIFORNIA COAST. THIS SHORTWAVE
WILL CONTINUE MOVING IN A NORTHEAST DIRECTION...REACHING THE WESTERN
DAKOTAS 12Z THURSDAY...AND INTO THE EASTERN DAKOTAS BY 00Z FRIDAY.
THE RESULT WILL BE A MENTION OF CHANCE OF SHOWERS AND THUNDERSTORMS
WEDNESDAY NIGHT...INCREASING TO LIKELY POPS WEST AND CENTRAL NORTH
DAKOTA THURSDAY. THIS SHORTWAVE DEPARTS THURSDAY EVENING FOLLOWED BY
OUR NEXT CLOSED UPPER LOW...WHICH IS CURRENTLY LOCATED OVER WESTERN
BRITISH COLUMBIA. THIS UPPER LOW WILL MOVE INTO ALBERTA 12Z THURSDAY
THEN CONTINUE EAST INTO MANITOBA BY 12Z SATURDAY. IN DOING SO...A
SURFACE COLD FRONT WILL DRAG THROUGH WESTERN AND CENTRAL NORTH
DAKOTA FRIDAY/FRIDAY NIGHT. THE LATEST GFS IS DRY FRIDAY WHILE THE
SREF AND ECMWF KEEP A SOME MENTION OF PRECIPITATION FAR NORTH AND
SOUTHWEST. WILL CARRY A SLIGHT CHANCE IN THE ABOVE MENTIONED
AREAS. A BRIEF PERIOD OF DRY WEATHER IS STILL ON TRACK FOR FRIDAY
NIGHT AND SATURDAY AS A TRANSITORY RIDGE SHIFTS THROUGH.
SHOWER/THUNDERSTORM CHANCES INCREASE OVER SOUTHERN NORTH DAKOTA
SATURDAY NIGHT THROUGH SUNDAY AS THE NEXT SHORTWAVE TROUGH LIFTS
FROM NORTHEAST WYOMING INTO SOUTH DAKOTA. BY MONDAY AND
TUESDAY...BOTH THE GFS AND ECMWF SHOW AN AMPLIFYING CENTRAL CONUS
RIDGE TAKING CONTROL AS A TROUGH DEVELOPS ALONG THE WEST AND EAST
COASTS. THIS WILL PROMOTE GENERALLY DRY AND WARMER CONDITIONS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 900 PM CDT TUE AUG 4 2015

VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD OUTSIDE OF
THUNDERSTORMS. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO MOVE
INTO FAR WESTERN NORTH DAKOTA LATE THIS EVENING...APPROACHING
KISN/KDIK AROUND 06-07Z...KBIS/KMOT AROUND 12-14 UTC AND KJMS
AFTER 18 UTC. ALSO KEPT A VCTS AT KBIS AND KMOT AFTER 16-18 UTC
RESPECTIVELY.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...TWH
SHORT TERM...AYD
LONG TERM...KS
AVIATION...TWH


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