Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 072022
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
322 PM CDT MON JUL 7 2014

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 311 PM CDT MON JUL 7 2014

WATER VAPOR SATELLITE IMAGE SHOWING SHORTWAVE TROUGH EXTENDING
THROUGH SOUTHERN MANITOBA INTO NORTHWEST NORTH DAKOTA ALONG A
LINE OF RECENTLY INTENSIFYING CONVECTION. A SECONDARY AREA OF
SHOWERS WITH ISOLATED THUNDERSTORMS LIES ACROSS THE SOUTH CENTRAL.
MAIN CHALLENGE TONIGHT WILL BE TRENDING BOTH AREAS EASTWARD WITH
GENERALLY DECREASING INTENSITY AFTER 7 PM CDT.

AFTER MIDNIGHT ALL CONVECTION SHOULD END WITH GENERALLY
DECREASING CLOUDS. TUESDAY WILL STILL BE PLAGUED WITH CYCLONIC
COOL FLOW ALOFT OVER EASTERN NORTH DAKOTA WHICH SHOULD SUPPORT
WIDELY SCATTERED THUNDERSTORMS. LOWS TONIGHT IN THE 50S. NOT AS
COOL TUESDAY BUT IN THE LOWER TO MID 70S.


.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 311 PM CDT MON JUL 7 2014

THE 500MB HEIGHT PATTERN PER GFS/ECMWF EXHIBIT TWO SIGNIFICANT
SHORTWAVE TROUGHS TO AFFECT WESTERN AND CENTRAL NORTH DAKOTA WITH
STRONG TO POSSIBLY SEVERE THUNDERSTORMS. THERE IS GOOD AGREEMENT
WITH THE FIRST SHORTWAVE...AFFECTING THE FORECAST AREA THURSDAY
AFTERNOON INTO THURSDAY NIGHT. THE SECOND SHORTWAVE REMAINS
UNCERTAIN...BUT COULD POSSIBLY PRODUCE MORE THUNDERSTORMS SATURDAY
INTO SUNDAY. NEAR THE END OF THE LONG TERM PERIOD A NORTHWEST FLOW
IS FORECAST TO BECOME ESTABLISHED RESULTING IN BELOW NORMAL
TEMPERATURES.

FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...OVERALL A DRY WEATHER
SCENARIO AS A 700MB-500MB RIDGE AXIS OVR THE NORTHERN ROCKIES WILL
DOMINATE...CRESTING OVER CENTRAL NORTH DAKOTA WEDNESDAY NIGHT. A LEE
SIDE TROUGH WILL ALREADY HAVE BECOME ESTABLISHED BEHIND THE RIDGE IN
EASTERN MONTANA WEDNESDAY AFTERNOON WITH A MID LEVEL WESTERLY FLOW
AND WARM AIR ADVECTION OFF THE HIGHER TERRAIN. A SLIGHT CHANCE OF
THUNDERSTORMS POSSIBLE AFTER 06Z THURSDAY IN THE SOUTHWEST WITH DRY
CONDITIONS ELSEWHERE.

THURSDAY THROUGH THURSDAY NIGHT...AN APPROACHING SHORTWAVE INTO EASTERN
MONTANA WILL ALLOW THE AFOREMENTIONED LEE SIDE TROUGH TO BECOME A
FORMIDABLE COLD FRONT THURSDAY MORNING. THIS COLD FRONT WILL THEN
PROGRESS INTO WESTERN NORTH DAKOTA THURSDAY AFTERNOON...AND CENTRAL
NORTH DAKOTA THURSDAY NIGHT. BY 12Z FRIDAY...THE COLD FRONT IS
FORECAST IN THE JAMES RIVER VALLEY. THE GFS BUFKIT SOUNDINGS
ADVERTISE ENOUGH CIN FROM MINOT TO BISMARCK AND EAST TO JAMESTOWN TO
POSSIBLY SUPPRESS CONVECTION UNTIL AFTER 00Z FRIDAY...WITH WESTERN
NORTH DAKOTA THE BETTER LOCATION FOR SHOWERS/THUNDERSTORMS THURSDAY
AFTERNOON. CAPE VALUES OF 1500-2000 J/KG WITH 0-6KM SHEAR VALUES OF
30KT TO 35KT ARE FORECAST IN THE WEST THURSDAY AFTERNOON. WILL NEED
TO MONITOR CENTRAL NORTH DAKOTA THURSDAY NIGHT AS THE CAP WEAKENS
WITH THE APPROACH OF THE SURFACE COLD FRONT AND SHORTWAVE ALOFT.

FRIDAY INTO FRIDAY NIGHT...A BRIEF REPRIEVE IN SHOWERS AND
THUNDERSTORMS AS A WESTERLY FLOW SUPPORTS WEAK HIGH PRESSURE
DRIFTING ACROSS WESTERN AND CENTRAL NORTH DAKOTA. THE NEXT SHORTWAVE
AND SURFACE LOW PRESSURE MOVE INTO EASTERN MONTANA FRIDAY NIGHT.

FOR SATURDAY INTO SUNDAY...THE ECMWF IS DRY SATURDAY HAVING MOVED
THE SHORTWAVE FROM EASTERN MONTANA FRIDAY NIGHT INTO SOUTH DAKOTA
SATURDAY. IN DOING SO SCATTERED SHOWERS AND THUNDERSTORMS ARE
ADVERTISED ALONG THE ND/SD BORDER FRIDAY NIGHT. THE ECMWF IS FASTER
WITH A DEEP CLOSED LOW DEVELOPING OVER HUDSON BAY AND MOVING IT
SOUTH WITH TIME. THE EC SHIFTS VERY COOL AIR INTO NORTHEAST NORTH
DAKOTA SUNDAY AFTERNOON AND ACROSS ALL OF WESTERN AND CENTRAL NORTH
DAKOTA SUNDAY NIGHT AND MONDAY. H850 TEMPS RANGE FROM +6C IN THE
TURTLE MOUNTAINS MONDAY AFTERNOON TO +13C IN THE SOUTHWEST. ALL OF
THIS IS PRECEDED BY SHOWERS AND THUNDERSTORMS SUNDAY AFTERNOON AND
EVENING IN EAST CENTRAL NORTH DAKOTA.

THE GFS IS SLOWER WITH THE ABOVE SCENARIO. THIS RESULTS IN A MORE
GENEROUS THREAT FOR SHOWERS AND THUNDERSTORMS SATURDAY AND SUNDAY
ACROSS WESTERN AND CENTRAL NORTH DAKOTA...WITH THE COOLER AIR NOT
ARRIVING INTO THE TURTLE MOUNTAINS UNTIL MONDAY NIGHT AND TUESDAY.
MUCH UNCERTAINTY ON THE EVOLUTION AND STRENGTH OF THE NORTHWEST FLOW
OVER THE WEEKEND AND INTO NEXT WEEK.



&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 311 PM CDT MON JUL 7 2014

AN UPPER LEVEL DISTURBANCE MOVING ACROSS NORTH DAKOTA MONDAY
AFTERNOON WILL MAINTAIN SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS ACROSS NORTHERN AND CENTRAL NORTH DAKOTA. THIS
CONVECTION WILL SUBSIDE AFTER DARK WITH VFR EXPECTED. HIGH
PRESSURE WILL BUILD IN ON TUESDAY.

&&

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

$$

SHORT TERM...WAA
LONG TERM...KS
AVIATION...WAA





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