Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 301437
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
937 AM CDT SAT AUG 30 2014

.UPDATE...
ISSUED AT 930 AM CDT SAT AUG 30 2014

INITIAL WAVE OF CONVECTION NOW PROGRESSING THROUGH EASTERN MONTANA
BUT THIS CONTINUES TO WEAKEN AS IT PUSHES EAST. EXPECT STRONGER
CONVECTION TO DO ITS APPROACH LATER THIS AFTERNOON...WHICH IS
SUPPORTED BY LATEST HIGH RES GUIDANCE. HAVE ADDED MENTION OF
POSSIBLE SEVERE OVER SOUTHWESTERN NORTH DAKOTA AS MODELS CONTINUE
TO SHOW STRENGTHENING INSTABILITY BY THAT TIME WITH ADEQUATE SHEAR
FOR ROTATING UPDRAFTS. HAVE ADJUSTED POPS SOME WITH THE EXPECTED
TIMING OF THIS. UPDATES HAVE BEEN SENT.

UPDATE ISSUED AT 645 AM CDT SAT AUG 30 2014

REFINED THE FOG AREA BASED ON SATELLITE/SURFACE REPORTS. ROLLA IN
THE UPPER 30S THIS MORNING.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 405 AM CDT SAT AUG 30 2014

FOCUS IN THE SHORT TERM WILL BE ON THE SEVERE THREAT AND QPF TODAY
AND TONIGHT.

THE 00 UTC MODEL GUIDANCE IS IN GOOD AGREEMENT OF A POTENT SHORT
WAVE PROGRESSING WEST ACROSS NORTH DAKOTA THIS AFTERNOON AND
TONIGHT. SURFACE LOW SHOULD SET UP IN WESTERN SOUTH DAKOTA THIS
AFTERNOON THEN TRACK NORTHEAST THROUGH THE NIGHT AS A FRONTAL
BOUNDARY PUSHES STRAIGHT WEST TO EAST ACROSS NORTH DAKOTA.

MODERATE INSTABILITY AND SHEAR VALUES ALONG WITH AMPLE MID LEVEL
LAPSE RATES WILL BE ENOUGH FOR STRONG TO SEVERE STORMS THIS
AFTERNOON AND EVENING. SPC HAS PLACED SOUTHWESTERN PORTIONS OF THE
STATE IN A SLIGHT RISK. THE MAIN THREATS WILL BE LARGE HAIL AND
DAMAGING WINDS. HEAVY RAIN FROM STORMS WILL ALSO BE POSSIBLE DUE TO
AMPLE LOW LEVEL MOISTURE. AS THE SYSTEM PROGRESSES INTO THE EARLY
EVENING AND NIGHT EXPECT MORE OF A WIDESPREAD RAIN EVENT AS DEEP
LAYER SHEAR VALUES MAY NOT BE ENOUGH TO SUSTAIN SUPERCELLS FOR LONG.

AS FOR QPF MODELS ARE IN AGREEMENT OF PLACING HEAVY RAINFALL IN THE
SOUTHWEST WHERE THE GREATEST SEVERE THREAT WILL BE. FROM THERE
MODELS SHOW THE HEAVIER RAINFALL TOTALS PROGRESSING EAST NORTHEAST
THROUGH THE STATE. HOWEVER...MODELS DIVERGE A BIT WHERE THE HEAVIER
RAIN WILL FALL. THE 00 UTC RUN OF THE ECMWF DIFFERS FROM BOTH THE
GFS AND NAM RUNS BY PLACING A BULLSEYE OF QPF IN THE JAMES RIVER
VALLEY WHILE THE NAM AND GFS KEEP THE HEAVIER TOTALS FURTHER NORTH
IN THE DEVILS LAKE AREA. FOR NOW STICKING WITH A BLEND OF THE 3 MODELS
FOR THE QPF FORECAST AND WILL KEEP AN EYE OUT TO SEE IF THEY MERGE
INTO A MORE CONSENSUS TRACK FOR THE HEAVIEST RAIN IN LATER RUNS.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 405 AM CDT SAT AUG 30 2014

BROAD H500 COOL CYCLONIC FLOW ALOFT REMAINS IN PLACE THROUGH MID
WEEK. DO NOT SEE ANY BIG WEATHER PROBLEMS WITH THIS FLOW BUT THERE
WILL BE SCATTERED TO WIDELY SCATTERED SHOWERS AND THUNDERSTORMS
SUNDAY THROUGH TUESDAY. EXPECT COOLER WEATHER WITH HIGHS IN THE
UPPER 60S TO THE MIDDLE 70S SUNDAY AND MONDAY AS RELATIVELY COOLER
AIR ENTERS THE REGION. SUNDAY WILL ALSO BE A BIT BREEZY AT 15 TO
25 MPH WINDS. MORNING LOWS COULD DIP INTO THE 40S MONDAY AND TUESDAY
BUT AS OF YET DO NOT SEE EARLY FROST ISSUES. BY THE MID TO END OF
THE WEEK THE MID LEVEL FLOW BECOMES MORE WESTERLY IN ADVANCE OF AN
H500 SHORTWAVE TROUGH DROPPING SOUTH INTO SOUTHWEST CANADA. THIS
SHORTWAVE WILL EVENTUALLY IMPACT THE NORTHERN PLAINS THURSDAY
INTO THE WEEKEND WITH SCATTERED THUNDERSTORMS AND A PASSAGE OF
ANOTHER COLD FRONT WILL BRING COOLER WEATHER THURSDAY AND
FRIDAY...AT LEAST BACK INTO THE 60S TO LOWER 70S.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 645 AM CDT SAT AUG 30 2014

THE FORECAST PROBLEM THIS MORNING REMAINS FOG DEVELOPMENT. THE
FOG WILL BE IMPACTING PRIMARILY KBIS THROUGH 14Z. AT TIMES FOG
COULD BE DENSE CAUSING LIFR CONDITIONS. LATER IN THE DAY A COLD
FRONT WILL PASS FROM WEST TO EAST AND WILL BE THE FOCUS FOR
NUMEROUS SHOWERS AND THUNDERSTORMS. FOR NOW HAVE VCTS IN FOR
KISN...KDIK...KMOT...AND KBIS.


&&

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

$$

UPDATE...JJS
SHORT TERM...MM
LONG TERM...WAA
AVIATION...WAA/MM





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