Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 230845
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
345 AM CDT WED JUL 23 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 340 AM CDT WED JUL 23 2014

FORECAST ISSUES IN THE SHORT TERM ARE THUNDERSTORM CHANCES.

WARM AIR ADVECTION WAS BEING AIDED BY A WEAK MID LEVEL VORTICITY
MAXIMA TO PRODUCE SOME CONVECTION BETWEEN WILLISTON AND BISMARCK
EARLY THIS WEDNESDAY MORNING. THE HIGH RESOLUTION MODELS HAVE BEEN
PICKING UP ON THIS AND THE LATEST RUNS INCREASE THE COVERAGE OF
THAT THROUGH MID MORNING BEFORE DISSIPATING STORMS AS THEY PUSH
EAST INTO LESS UNSTABLE AIR.

FOLLOWING THAT IS THE TIMING OF THE NEXT...MORE SIGNIFICANT...
WAVE FOR TONIGHT INTO THURSDAY.

THE H5 LONG WAVE RIDGE AXIS IS OVER THE MONTANA AND NORTH DAKOTA
BORDER LATE THIS AFTERNOON. THIS SHOULD SUPPRESS CONVECTION ON THE
NORTH DAKOTA SIDE...AND WEAKEN STORMS MOVING TOWARD THE BORDER
FROM MONTANA. THIS AXIS SHIFTS EAST AND IS BEATEN DOWN BY SHORT
WAVES IN THE UPSTREAM SOUTHWEST DIFFLUENT FLOW ALOFT. ALONG WITH
DEEPENING LOW PRESSURE AND AN INCREASING THERMAL RIDGE...THE
ATMOSPHERE OVER WESTERN NORTH DAKOTA DESTABILIZES SIGNIFICANTLY
OVERNIGHT TONIGHT WITH INCREASING STORM CHANCES.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 340 AM CDT WED JUL 23 2014

THE MAIN FEATURES IN THE EXTENDED PERIOD CONTINUE TO BE AN UPPER LOW
OFF THE WA/OR COAST AND ITS INTERACTION WITH THE DOWNSTREAM H500
RIDGE OVER THE NORTHERN PLAINS. AS THE UPPER LOW MOVES EAST AND
FLATTENS AND RAMS DOWN THE RIDGE...A COLD FRONT AT THE SURFACE
WILL POSITION ITSELF ACROSS EASTERN MONTANA BY THURSDAY AFTERNOON.
GFS APPEARS TO BE THE SLOWEST OF THE MODELS WITH THE NAM PROBABLY
THE FASTEST. THE ECMWF IS BETWEEN AND PROBABLY THE BEST FOR TIMING
THE FRONT INTO WESTERN NORTH DAKOTA BY 7 PM THURSDAY. NARROW BUT
STRONG THERMAL RIDGE AT H850 AND FRONTAL MIXING SHOULD ALLOW/SUPPORT
HIGH TEMPERATURES IN THE LOWER TO NEAR MIDDLE 90S ACROSS THE WEST
THURSDAY. THUNDERSTORMS...A FEW POSSIBLY SEVERE WITH STRONG WINDS
AND HAIL THE MAIN THREATS WILL ACCOMPANY THE FRONTS PROGRESSION INTO
THE STATE THURSDAY AFTERNOON AND EVENING. ON FRIDAY COOLER BUT STILL
REASONABLY MILD TEMPERATURES IN THE UPPER 70S TO LOWER 80S SHOULD BE
THE RULE. SHOWERS AND ISOLATED THUNDERSTORMS SHOULD BE LIMITED TO
THE EAST. ONE MORE DAY OF SHOWERS/SCATTERED THUNDERSTORMS ON
SATURDAY AS THE SLOW MOVING UPPER LOW TRACKS SOUTH ACROSS MINNESOTA.
WHILE THE STATE WILL GENERALLY BE ON THE DRY SIDE OF THE UPPER LOW
CANT RULE OUT SHOWERS AS COOL AIR ALOFT SHOULD SUPPORT SOME
INSTABILITY. AS THE UPPER LOW DRIFTS EAST AND RIDGE POPS UP IN
MONTANA SUNDAY THROUGH TUESDAY SHOULD BE DRY WITH GENERALLY PLEASANT
TEMPERATURES AND HUMIDITY FOR THIS TIME OF YEAR.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY)
ISSUED AT 340 AM CDT WED JUL 23 2014

-SHRA / -TSRA WERE INCREASING IN COVERAGE EARLY WEDNESDAY MORNING
SOUTH OF MINOT. THESE WILL EXPAND THIS MORNING THEN MOVE EAST AND
DISSIPATE FOR THE AFTERNOON. MORE -TSRA ARE FORECAST IN THE WEST
AFTER 00Z/24TH.

&&

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

$$

SHORT TERM...JPM
LONG TERM...WAA
AVIATION...JPM





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