Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 270900
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
400 AM CDT WED MAY 27 2015

.SHORT TERM...(TODAY AND TONIGHT)

ISSUED AT 400 AM CDT WED MAY 27 2015

THE MAIN FOCUS FOR THE SHORT TERM IS THUNDERSTORMS.

THERE IS GOOD AGREEMENT BETWEEN THE GLOBAL MODELS AND THE HIGHER
RESOLUTION SHORT TERM MODELS. THEY BOTH DEPICT A ROBUST SHORTWAVE
TROUGH ENTERING EASTERN MONTANA BY EARLY AFTERNOON. AHEAD OF THIS
WAVE...A SURFACE LOW IS PROGGED TO DEVELOP/DEEPEN ACROSS EASTERN
MONTANA AND THE WESTERN DAKOTAS. THESE TWO FEATURES WILL PROVIDE
AMPLE FORCING FOR WIDESPREAD PRECIPITATION DEVELOPMENT.

A RESIDUAL COLD FRONT HAS STALLED ACROSS NORTHERN NORTH DAKOTA.
THE HIGH-RES MODELS ARE INDICATING THUNDERSTORM DEVELOPMENT ALONG
THE FRONT THIS AFTERNOON. THESE THUNDERSTORMS WOULD BE WELL AHEAD
OF THE MAIN LOW OUT WEST. THEREFORE...TWO ROUNDS OVER
THUNDERSTORMS ARE POSSIBLE ACROSS PORTIONS OF NORTHERN AND CENTRAL
NORTH DAKOTA...COLD FRONT INDUCED EARLY THIS AFTERNOON AND THEN
TROUGH/LOW INDUCED THIS EVENING.

A MOIST AND UNSTABLE BOUNDARY LAYER IS PRESENT ACROSS NORTH
DAKOTA. LOOKING AT FORECAST SOUNDINGS...THE RAP AND NAM HAVE
NEARLY 1000 J/KG CAPE AND STEEP LAPSE RATES AROUND 7 C/KM FOR THIS
AFTERNOON. HOWEVER...SHEAR IS FORECAST TO BE RATHER LACKING AND
UNIDIRECTIONAL. THEREFORE...SOME THUNDERSTORMS COULD BE RATHER
STRONG WITH GUSTY WINDS AND SMALL HAIL...BUT WIDESPREAD SEVERE
WEATHER IS NOT ANTICIPATED. ADDITIONALLY...WITH PWATS AROUND
1.0-1.25 INCHES...SOME HEAVY RAIN AMOUNTS COULD QUICKLY ACCUMULATE
WITH THESE THUNDERSTORMS.


.LONG TERM...(THURSDAY THROUGH TUESDAY)

ISSUED AT 400 AM CDT WED MAY 27 2015

TWO ACTIVE PERIODS...WITH A DRY AND COOL COUPLE OF DAYS IN THE
MIDDLE...WILL CONTINUE TO HIGHLIGHT THE LONG TERM PERIOD.

UPPER LEVEL TROUGH WILL BE MOVING THROUGH THE DAKOTAS THURSDAY
INTO THURSDAY NIGHT. BEST CHANCE FOR ACCUMULATING RAINFALL WILL BE
ACROSS MY NORTH NEAR THE TRACK OF A MID LEVEL S/WV AND NORTH OF AN
AREA OF LOW PRESSURE...AND ACROSS MY SOUTHEAST WHERE SCATTERED
THUNDERSTORMS SHOULD DEVELOP WITH INCREASING DIURNAL INSTABILITY.
A STABLE AIRMASS ASSOCIATED WITH SURFACE HIGH PRESSURE WILL THEN
DEVELOP FROM NORTH TO SOUTH LATE THURSDAY NIGHT INTO FRIDAY ACROSS
THE NORTHERN PLAINS...AND REMAINS IN PLACE THROUGH SATURDAY. HIGHS
FRI-SAT COMFORTABLE AT 55-65. DRY AIR ACCOMPANYING THE SFC HIGH
WILL BRING A CHANCE FOR WIDESPREAD FROST FRIDAY NIGHT-SAT MORNING
WITH FORECAST LOWS IN THE 30S.

ROBUST RETURN FLOW WEST SATURDAY AND AREA WIDE SUNDAY INTO EARLY
NEXT WEEK AS HIGH PRESSURE MOVES OFF TO OUR EAST. STRONG MOISTURE
ADVECTION ALONG WITH HIGH TEMPERATURES WARMING INTO THE 70S TO
LOWER 80S WILL RESULT IN INCREASING INSTABILITY MONDAY INTO THE
MIDDLE PORTIONS OF THE WEEK. 12Z GFS/EC MODELS STILL PROJECT
ANYWHERE FROM 1500-3500 J/KG OF MUCAPE ALONG WITH AMPLE WIND SHEAR
FOR THE TUESDAY-WEDNESDAY TIMEFRAME ONCE OUR FLOW ALOFT
TRANSITIONS TO SOUTHWESTERLY. STILL UNCERTAINTY BUT DOES APPEAR TO
BE A VERY ACTIVE/WET 2-3 DAYS NEXT WEEK AND PERHAPS THROUGH THE
ENTIRE WORK WEEK.


&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)

ISSUED AT 345 AM CDT WED MAY 27 2015

VFR CONDITIONS ARE EXPECTED...WITH OCCASIONAL MVFR IN
THUNDERSTORMS POSSIBLE...AT ALL TERMINALS THROUGH THE TAF PERIOD.
SHOWERS AND THUNDERSTORMS ARE POSSIBLE BEGINNING EARLY THIS
AFTERNOON. INITIAL STORMS WILL LIKELY BE RATHER ISOLATED...WITH
MORE WIDESPREAD THUNDERSTORMS LIKELY THIS EVENING.


&&

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

$$

SHORT TERM...AJ
LONG TERM...NH
AVIATION...AJ


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