Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 210256
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
956 PM CDT WED AUG 20 2014

.UPDATE...
ISSUED AT 952 PM CDT WED AUG 20 2014

THIS UPDATE REMOVES BURLEIGH/SIOUX COUNTIES FROM WATCH. FOCUS FOR
HEAVY RAINFALL FAR SOUTH CENTRAL...ISSUED AREAL FLOOD ADVISORY
EMMONS...MCINTOSH AND LOGAN COUNTIES THROUGH 3 AM CDT.

UPDATE ISSUED AT 916 PM CDT WED AUG 20 2014

TRIMMED THE SEVERE THUNDERSTORM WATCH FROM MORTON AND GRANT
COUNTIES. HEAVY RAIN WILL BE THE MAIN THREAT FROM EMMONS TO
LOGAN AND MCINTOSH COUNTIES...POSSIBLY UP INTO KIDDER COUNTY AS
WELL. FLASH FLOOD GUIDANCE THERE BETWEEN 2 AND 3 INCHES IN THREE
HOURS. WILL MONITOR CLOSELY.

UPDATE ISSUED AT 717 PM CDT WED AUG 20 2014

UPDATE TO REMOVE ADAMS AND HETTINGER COUNTIES FROM SEVERE
THUNDERSTORM WATCH.

UPDATE ISSUED AT 656 PM CDT WED AUG 20 2014

LINE OF THUNDERSTORMS MOVING THROUGH SOUTH CENTRAL NORTH DAKOTA
WITH MAINLY HEAVY RAIN. ISOLATED LARGE HAIL AND WIND THREAT
CONTINUES AS WELL.

UPDATE ISSUED AT 514 PM CDT WED AUG 20 2014

THIS UPDATE FOR THE SEVERE THUNDERSTORM WATCH 469 UNTIL 11 PM CDT.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 244 PM CDT WED AUG 20 2014

SEVERE THUNDERSTORM POTENTIAL AND HEAVY RAINFALL WILL HIGHLIGHT
THE SHORT TERM FORECAST.

LITTLE CHANGE FROM THE PREVIOUS UPDATE. THE BEST POTENTIAL FOR
SEVERE CONVECTION REMAINS ALONG AND EAST OF THE HIGHWAY 83
CORRIDOR WHERE FILTERED SUNSHINE THROUGH MID TO HIGH LEVEL CLOUD
COVER HAS ALLOWED FOR TEMPERATURES TO WARM INTO THE LOWER
80S...AMID A MOIST AIRMASS WITH DEW POINTS GENERALLY IN THE UPPER
60S. SOME WEAK ML INHIBITION REMAINS...WHICH LEADS TO UNCERTAINTY
IF THE BOUNDARY LAYER CAN HEAT OUT GIVEN THE AFOREMENTIONED CLOUD
COVER. EFFECTIVE DEEP LAYER SHEAR IS MARGINAL...ON THE ORDER OF
THE 25-30 KTS...SUPPORTING A POSSIBLE SUPERCELL OR TWO IF
INHIBITION CAN BE OVER COME. GREATER CONVECTIVE STRENGTHENING
LOOKS TO BE DELAYED UNTIL 21-00 UTC WITH GREATER LOW LEVEL
CONVERGENCE AHEAD OF THE COLD FRONT PROPAGATING THROUGH WESTERN
NORTH DAKOTA. IN ADDITION TO LARGE HAIL AND DAMAGING WINDS...HEAVY
RAIN WILL ALSO BE A PRIMARY THREAT AS CORFIDI VECTORS REMAIN SLOW
BETWEEN 10 AND 20 KTS...WITH CONTINUED INCREASING LOW LEVEL
MOISTURE TRANSPORT. FINALLY...CONTINGENT UPON SEVERE CONVECTIVE
DEVELOPMENT...AN ISOLATED TORNADO CANNOT BE RULED OUT WITH 0-1 KM
SHEAR OF 15-20 KTS AHEAD OF THE FRONT. STORMS WILL PROPAGATE EAST
THROUGH THE EVENING...WITH THE SEVERE THREAT WANING AFTER SUNSET.
A BRIEF LULL IN PRECIPITATION MAY BE IN STORE FOR MUCH OF WESTERN
AND CENTRAL NORTH DAKOTA ON THURSDAY WITH WEAK SHORTWAVE RIDGING
ALOFT BEFORE THE WET PATTERN IN THE EXTENDED.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 244 PM CDT WED AUG 20 2014

ACTIVE SOUTHWESTERLY FLOW CONTINUES THROUGH THE MAJORITY OF THE
EXTENDED KEEPING PRECIPITATION CHANCES IN THE FORECAST. MAJOR
CONCERN IS GOING INTO THE END OF THE WORK WEEK INTO THE WEEKEND AS
MODELS CONTINUE THEIR CONSISTENCY WITH GENERALLY HIGH QPF...WHICH IF
THIS COMES TO FRUITION MAY RESULT IN SOME HYDRO CONCERNS. NATIONAL
GUIDANCE KEEPS THE HIGHEST QPF VALUES THROUGH THE WEEKEND MAINLY
OVER WESTERN NORTH DAKOTA...BUT A SLIGHT SHIFT IN THE MODELS
SOLUTIONS OVER THE NEXT COUPLE DAYS COULD BRING THE CONCERNS FURTHER
EAST. WILL HAVE TO WATCH THIS CLOSELY. AS FOR TEMPERATURES...COOLER
AIRMASS WILL START TO SINK IN FRIDAY WITH WELL BELOW AVERAGE
TEMPERATURES EXPECTED BY THE WEEKEND...CONTINUING INTO EARLY NEXT
WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 952 PM CDT WED AUG 20 2014

MAIN THREAT FOR AVIATION WILL BE THUNDERSTORMS KJMS THIS EVENING.
AT 930 PM CDT...A COLD FRONT EXTENDED FROM SOUTHEAST SASKATCHEWAN
THROUGH NORTHWEST NORTH DAKOTA. SURFACE OW PRESSURE ACROSS CENTRAL
SOUTH DAKOTA WITH A WARM FRONT EXTENDING SOUTHEAST WILL BE THE
FOCUS FOR THUNDERSTORMS WITH HEAVY RAIN SOUTHEAST NORTH DAKOTA.
POTENTIAL FOR IFR CONDITIONS IN THUNDERSTORMS...OTHERWISE VFR
EXPECTED.

&&

.HYDROLOGY...
ISSUED AT 244 PM CDT WED AUG 20 2014

HYDROLOGIC CONCERNS ARE CENTERED UPON THE STRONG STORM SYSTEM
FORECAST TO IMPACT THE NORTHERN PLAINS SATURDAY AND SUNDAY. WHILE
HEAVY RAINFALL IS CERTAIN...ITS EXACT PLACEMENT WILL REMAIN A BIT
UNCERTAIN OVER THE NEXT 24 TO 36 HOURS AS THE MODEL TRACKS
CONTINUE TO WOBBLE A BIT. GIVEN UNCERTAINTY...WILL HOLD OFF ON A
WATCH FOR NOW AND HIGHLIGHT THE POTENTIAL CONCERNS IN THE HWO AND
ISSUE AN SPS.

&&

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

$$

UPDATE...WAA
SHORT TERM...AYD
LONG TERM...JJS
AVIATION...WAA
HYDROLOGY...AYD





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