Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 280300
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1000 PM CDT WED MAY 27 2015

.UPDATE...
ISSUED AT 951 PM CDT WED MAY 27 2015

LIGHTNING RATES HAVE DECREASED CONSIDERABLY DURING THE PAST HOUR.
DROPPED THE THUNDERSTORM CHANCES AND WEST HIGH PROBABILITIES OF
SHOWERS CENTRAL.

UPDATE ISSUED AT 702 PM CDT WED MAY 27 2015

LATEST RADAR AND SATELLITE IMAGERY SHOWING A LINE OF SHOWERS AND
THUNDERSTORMS ACROSS WEST CENTRAL NORTH DAKOTA MOVING EAST MUCH
LIKE THE LATEST HRRR PROJECTS. BASED ON TRENDS BUMPED UP THE POPS
TO DEFINITE ACROSS CENTRAL NORTH DAKOTA. LOOKS LIKE A LULL IN
ACTIVITY FAR WEST WITH INCREASING CHANCES LATE TONIGHT WITH THE
APPROACHING COLD FRONT ON THURSDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 310 PM CDT WED MAY 27 2015

THUNDERSTORM CHANCES THIS AFTERNOON THROUGH TONIGHT AND AGAIN
THURSDAY HIGHLIGHT THE SHORT TERM FORECAST.

WILL CONTINUE TO FOLLOW THE HIGH RESOLUTION CONVECTIVE  ALLOWING
GUIDANCE....NAMELY THE 17-19 UTC HRRR ITERATIONS AND 12 UTC WRF-
ARW/NMM FOR THE EVOLUTION OF CONVECTION THIS AFTERNOON AND THROUGH
THE NIGHT GIVEN THEIR GOOD HANDLING OF THE EVENT THUS FAR.
SCATTERED THUNDERSTORMS CONTINUE TO DEVELOP ALONG THE STATIONARY
FRONTAL BOUNDARY THIS AFTERNOON ARCHING FROM NORTHWEST NORTH
DAKOTA INTO THE JAMES RIVER VALLEY. MORE NUMEROUS THUNDERSTORMS
CONTINUE ACROSS WESTERN NORTH DAKOTA NEAR THE SURFACE TROUGH AXIS.
AS DEEP LAYER SHEAR INCREASES ACROSS THE SOUTHWEST WITH THE
APPROACH OF STRONGER FORCING...MARGINAL SEVERE HAIL AND WINDS ARE
POSSIBLE LATE THIS AFTERNOON AND EVENING. CONVECTION ACROSS THE
WEST IS EXPECTED TO CONGEAL THIS EVENING AS IT PROPAGATES INTO
CENTRAL NORTH DAKOTA...LIFTING INTO THE DEVILS LAKE BASIN AND RED
RIVER VALLEY BY 09-11 UTC.

FOR THURSDAY...SPC HAS EXPANDED THEIR MARGINAL THREAT AREA IN THE
DAY TWO OUTLOOK TO INCLUDE MOST OF CENTRAL NORTH DAKOTA. ML CAPE
VALUES OF 1000-1500 J/KG ARE ANTICIPATED IN THE VICINITY OF THE
PRE-FRONTAL TROUGH AHEAD OF THE STRONG COLD FRONT ENTERING THE
NORTHWEST PORTION OF THE STATE. HOWEVER...DEEP LAYER SHEAR FOR
SUPERCELLS IS MARGINAL...ON THE ORDER OF 20-30 KTS. THUS...A FEW
STRONG TO SEVERE STORMS ARE POSSIBLE WITH LARGE HAIL AND DAMAGING
WINDS BEING THE PRIMARY THREATS.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 310 PM CDT WED MAY 27 2015

FROST POTENTIAL SATURDAY MORNING AND AN ACTIVE WEATHER PATTERN
NEXT WEEK HIGHLIGHT THE EXTENDED FORECAST.

A COOL FRIDAY IS EXPECTED IN THE WAKE OF THE AFOREMENTIONED COLD
FRONT IN THE SHORT TERM...WITH HIGHS IN THE UPPER 50S TO MID 60S.
AS A SURFACE RIDGE AXIS BUILDS INTO THE STATE ON FRIDAY...A COOL
FRIDAY NIGHT INTO SATURDAY MORNING IS POSSIBLE WITH LOWS IN THE 30S
AND POTENTIAL FROST. THEREAFTER...A RETURN TO AN ACTIVE WEATHER
PATTERN COMMENCES SUNDAY INTO WEDNESDAY AS THE UPPER LEVEL FLOW
PATTERN TRANSITIONS FROM ZONAL TO SOUTHWEST ALOFT. THIS WILL HAVE
TO BE MONITORED FOR SEVERE POTENTIAL. GIVEN GOOD AGREEMENT...A
BLEND OF THE 12 UTC DETERMINISTIC AND ENSEMBLE SUITES WERE USED
FOR MOST FIELDS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 951 PM CDT WED MAY 27 2015

AT 03Z SURFACE OBS AND HRRR DEPICT LOW PRESSURE OVER WEST CENTRAL
NORTH DAKOTA. SHOWERS AND THUNDERSTORMS ALONG A TROUGH LINE ACROSS
CENTRAL NORTH DAKOTA. MAIN THREAT FOR THUNDERSTORMS THROUGH 06Z
EXTEND FROM KBIS-KJMS THEN A DOWNTREND AFTER THAT. NAM MODEL STILL
FORECAST MVFR/IFR CONDITIONS FORMING AFTER 06Z KMOT- KISN THEN
EXTENDING SOUTH BY SUNRISE TO KBIS- KDIK. SOME UNCERTAINTY IF
THIS WILL BE IFR OF MORE MVFR. TRENDING TO THE MORE POSITIVE MVFR.

&&

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

$$
WAA
UPDATE...WAA
SHORT TERM...AYD
LONG TERM...AYD
AVIATION...WAA


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