Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 281517
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1017 AM CDT THU AUG 28 2014

.UPDATE...
ISSUED AT 1017 AM CDT THU AUG 28 2014

MADE SOME MINOR UPDATES TO POPS IN THE SOUTHEAST CWA AND ADJUSTED
SKY COVER BASED ON RADAR.

LATEST RAP FORECAST SOUNDINGS ARE SHOWING LIMITED INSTABILITY OVER
THE SOUTHEAST...THUS HAVE DROPPED THE MENTION OF THUNDER. WILL
TAKE A CLOSER LOOK AT TEMPERATURES LATE MORNING/EARLY AFTERNOON.
CLOUD SHIELD MIGHT HOLD TEMPERATURES BACK SOUTHEAST...BUT
ESPECIALLY THE WESTERN EDGE OF THE CLOUD SHIELD WOULD STILL HAVE A
GOOD SHOT OF REACHING FORECAST HIGHS AS WE GOT A WARM START.

UPDATE ISSUED AT 634 AM CDT THU AUG 28 2014

UPPER LOW BRUSHING BY SOUTHERN NORTH DAKOTA TODAY. RADAR AND
SURFACE REPORTS SHOW PRECIPITATION ACROSS NORTH CENTRAL SOUTH
DAKOTA. THIS AREA WILL BE ENTERING SOUTH CENTRAL/SOUTHEAST NORTH
DAKOTA THIS MORNING. AREAS OF FOG CONTINUE MAINLY FAR SOUTHWEST AND
NORTH CENTRAL. CURRENT FORECAST TRENDING WELL.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CDT THU AUG 28 2014

NEAR TERM CONCERNS/EARLY THIS MORNING...IS LOCALIZED DENSE FOG AT
HETTINGER. HAVE NOT SEEN MUCH EXPANSION IN THIS AREA PER SURFACE
OBS AND FOG/STRATUS LOOP...THUS WILL LIKELY UTILIZE A SHORT TERM
FORECAST TO COVER THIS. MID LEVEL CLOUDS EJECTING ACROSS WESTERN
SOUTH DAKOTA MAY BE ENOUGH TO HALT RADIATIONAL COOLING AND IMPROVE
VISIBILITIES AT HETTINGER. ANOTHER EARLY MORNING CONCERN IS THE
DEVELOPMENT OF SHOWERS IN FAR SOUTH CENTRAL AND INTO THE JAMES
RIVER VALLEY. LOCAL/REGIONAL RADAR SHOWS A LARGE SWATH OF SHOWERS
AND ISOLATED THUNDERSTORMS SLOWLY EDGING NORTH WITH TIME FROM
SOUTH DAKOTA.

FOR TODAY...MAIN CHANGE IN THE FORECAST WAS TO INCREASE POPS INTO
THE LIKELY AND CATEGORICAL RANGE ACROSS THE SOUTHERN JAMES RIVER
VALLEY. ALL MODEL SOLUTIONS PEG THE SOUTHEAST WITH AT LEAST A
THIRD OF AN INCH OF RAIN...POSSIBLY EVEN HIGHER AMOUNTS...DURING
THE MORNING AND INTO MID AFTERNOON. CURRENT RAINFALL AMOUNTS IN
PIERRE SOUTH DAKOTA WOULD SUPPORT THIS WITH 0.26 INCHES REPORTED
IN A 3HR PERIOD. ENOUGH INSTABILITY PER NAM/GFS PARAMETERS AND SPC
TO WARRANT A MENTION OF ISOLATED THUNDERSTORMS. LATEST WATER VAPOR
IMAGERY SHOWS A POTENT SHORTWAVE OVER CENTRAL SOUTH DAKOTA. THIS
IS FORECAST TO SHIFT INTO THE SOUTHERN JAMES RIVER VALLEY BY 18Z
WITH STRONG VERTICAL MOTION PER H85-H3 OMEGA FIELD. GIVEN THE
EXTENSIVE COVERAGE OF SHOWERS IN SOUTH DAKOTA CURRENTLY...AND
EXCELLENT MODEL AGREEMENT ON AREAL COVERAGE AND DURATION...HAVE HIGH
CONFIDENCE WITH LIKELY/CATEGORICAL POPS IN THE SOUTHEAST. POPS
QUICKLY TAPER OFF TO THE WEST AND NORTH WITH A TRANSITION TOWARD A
A MOSTLY SUNNY SKY ELSEWHERE. WENT WITH THE COOLER NAM/GFS MOS
TEMPERATURES IN THE SOUTHEAST WITH CLOUDS AND SHOWERS PERSISTING
THROUGH THE DAY...THUS HIGHS WILL ONLY REACH THE LOWER 70S. CONTRAST
THIS TO THE FAR WEST WHERE HIGHS WILL REACH 90 DEGREES AT WILLISTON.
THIS WARMING IN THE FAR WEST IS ALSO AHEAD OF AN ADVANCING COLD
FRONT WHICH WILL MOVE ACROSS THE NORTHWEST THURSDAY EVENING...AND
INTO CENTRAL NORTH DAKOTA AFTER MIDNIGHT. MODEL CONSENSUS IS FOR A
DRY FROPA OVERNIGHT WITH INCREASING POPS AFTER THE SHORT TERM PERIOD.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 315 AM CDT THU AUG 28 2014

INITIALLY...A COLD FRONT ASSOCIATED WITH A WEAK SHORTWAVE TROUGH
WILL BE MOVING THROUGH THE STATE FRIDAY MORNING. THE GFS/ECMWF
APPEAR TO BE THE MOST ROBUST WITH PF ALONG AND BEHIND THE FRONT
ACROSS SOUTHWEST NORTH DAKOTA. WILL FOCUS ON THE SOUTHWEST AND
EVENTUALLY SOUTH CENTRAL NORTH DAKOTA FOR SCATTERED TO WIDELY
SCATTERED THUNDERSTORMS. THIS WILL BE FOLLOWED BY A FAIRLY DRY
PERIOD FRIDAY NIGHT AND SATURDAY IN WEAK SUBSIDENCE BEHIND THE
SHORTWAVE TROUGH AND THE NEXT MORE SIGNIFICANT UPPER LOW DUE IN
SATURDAY AFTERNOON AND NIGHT. MODELS SEEM TO PRETTY MUCH PEG A
LINE OF THUNDERSTORMS ALONG AND AHEAD OF THE SHORTWAVE TROUGH AND
ASSOCIATED FRONTAL BOUNDARY SATURDAY NIGHT. WITH MODEL AGREEMENT
SATURDAY NIGHT INTO SUNDAY MORNING FEEL CONFIDENT IN RAISING POPS
TO AT LEAST LIKELY WITH AN AREA OF CATEGORICAL ACROSS MUCH OF
CENTRAL NORTH DAKOTA. ON SUNDAY SUBSIDENCE BEHIND THE
COLD/OCCLUDED FRONT SHOULD BRING IN COOLER/DRIER AIR BUT CANNOT
RULE OUT WIDELY SCATTERED POST FRONTAL SHOWERS WITH COOL CYCLONIC
FLOW ALOFT. MONDAY THROUGH WEDNESDAY SEE MAINLY NORTHWEST FLOW
ALOFT WITH ISOLATED SHOWERS/THUNDERSTORMS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1017 AM CDT THU AUG 28 2014

IFR CEILINGS CONTINUE AT KBIS AND KJMS AND SHOULD LIFT TO MVFR
LATE MORNING TO EARLY AFTERNOON. COULD SEE MVFR HOLD ON THROUGH
MID AFTERNOON...ESPECIALLY AT KJMS. VFR CONDITIONS EXPECTED AT
KDIK-KISN-KJMS.

&&

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

$$

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




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