000
FXUS63 KBIS 181127
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
627 AM CDT FRI APR 18 2014

.UPDATE...
ISSUED AT 627 AM CDT FRI APR 18 2014

FORECAST IS ON TRACK AND ONLY CHANGE WAS TO MATCH FORECAST
ELEMENTS TO LATEST OBS. RADAR SHOWING SOME WEAK RETURNS ACROSS
MONTANA...WHILE SURFACE OBS SHOW SOUTHEAST WINDS STRENGTHENING
ACROSS MOST OF CWA.

&&

.SHORT TERM...(TODAY AND TONIGHT)

ISSUED AT 402 AM CDT FRI APR 18 2014

FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE STRONG WINDS
DEVELOPING THIS MORNING AND AFTERNOON...CHANCES FOR RAIN NOW
THROUGH TONIGHT...AND THE POSSIBILITY OF A THUNDERSTORM FAR
SOUTHWEST/FAR SOUTH CENTRAL LATER TODAY INTO THIS EVENING. MODELS
IN FAIR AGREEMENT AND BASED THE SHORT TERM PERIOD ON A BLEND.

CURRENTLY...UPPER LEVEL RIDGE AXIS OVER THE HIGH PLAINS MOVING
EASTWARD AS A POTENT S/WV TROUGH OVER THE PACIFIC NORTHWEST
PROPAGATES INLAND. LEE SIDE CYCLOGENESIS UNDERWAY ACROSS ALBERTA
SOUTHWARD ACROSS MONTANA IN RESPONSE. BKN-OVC CLOUDS CONTINUE TO
STREAM ACROSS THE LOCAL AREA AHEAD OF THE RIDGE. INCREASING
THERMAL UPGLIDE EAST OF THE DEVELOPING SFC LOW RESULTING IN RADAR
RETURNS ACROSS THE REGION. CIGS GENERALLY 8K FEET AGL AND UP SO
DOUBT MUCH IS REACHING THE GROUND. THE EXCEPTION IS THE NORTHWEST
CORNER OF THE STATE WHERE CIGS HAVE DROPPED TO 4K FT AGL WITH KISN
REPORTING LIGHT RAIN PERIODICALLY THIS AM. THIS IS ALSO WHERE THE
STRONGEST THERMAL LIFT IS AT AND MOISTURE ADVECTION.

FOR PRECIPITATION OVER THE NEXT 24 HOURS OR SO...WILL GENERALLY
SEE CHANCES INCREASING ACROSS WESTERN NORTH DAKOTA TODAY SPREADING
EAST ACROSS THE REMAINDER OF THE FORECAST AREA THIS EVENING AS THE
UPPER LEVEL TROUGH/MID LEVEL LOW MOVES EAST ACROSS NORTHERN
MONTANA AND THE SFC LOW AND ITS ASSOCIATED FRONTAL BOUNDARIES MOVE
EAST ACROSS THE DAKOTAS. STRONG WAA THIS AFTERNOON/EVENING ACROSS
WESTERN AND CENTRAL SOUTH DAKOTA WILL NOSE INTO MY SOUTH DAKOTA
BORDER COUNTIES GENERATING LATE AFTERNOON/EVENING DESTABILIZATION.
4KM WRF INDICATES A WEAK CONVECTIVE COMPLEX DEVELOPING OVER FAR
SOUTHEASTERN MONTANA AND ADVANCING EAST-NORTHEAST FOR SEVERAL
HOURS. THUS ADDED THUNDERSTORMS TO THE FORECAST 22Z-06Z LATE THIS
AFTERNOON AND EVENING FAR SOUTHWEST AND FAR SOUTH CENTRAL.
PRECIPITATION WILL END AFTER MIDNIGHT AS FORCING ASSOCIATED WITH
THE UPPER LEVEL WAVE AND SFC LOW MOVE MORE INTO FAR EASTERN ND AND
MINNESOTA. EXPECT QPF TO REMAIN AT OR BELOW A QUARTER OF AN INCH
WITH THE HEAVIER PRECIPITATION REMAINING OFF TO OUR NORTH CLOSER
TO THE MID LEVEL LOW.

SOUTHEAST WINDS ALREADY ON THE INCREASE RIGHT NOW AS THE PRESSURE
GRADIENT CONTINUES TO TIGHTEN EAST OF THE DEEPENING SFC LOW. A
RATHER IMPRESSIVE PRESSURE GRADIENT WILL MATERIALIZE FOR
TODAY...GENERATING SUSTAINED SOUTHEAST WINDS AROUND 30 MPH AND
GUSTS TO 40 MPH ACROSS MY CENTRAL AND EAST. THUS HAVE HOISTED A
WIND ADVISORY FROM THIS MORNING THROUGH THE AFTERNOON (THROUGH MID
EVENING ACROSS THE JAMES RIVER VALLEY) WHERE WINDS ARE EXPECTED TO
BE STRONGEST. THERE MAY BE A PERIOD WHERE STRONG WINDS WILL OCCUR
ACROSS THE SOUTHWEST THIS MORNING/EARLY AFTERNOON. WILL MONITOR.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 402 AM CDT FRI APR 18 2014

PERIOD BEGINS WITH PROGRESSIVE PATTERN AND QUASI ZONAL
FLOW ACROSS NORTHERN CONUS WITH STRONG SHORT WAVE SKIRTING JUST
ALONG INTERNATIONAL BORDER...SUPPORTING SURFACE LOW AND ASSOCIATED
PRECIP DEPARTING TO EAST OF CWA. ANOTHER SHORTWAVE FOLLOWS SIMILAR
PATH...BUT BEST PRECIP CHANCES REMAIN NORTH OF THE BORDER SUNDAY
INTO MONDAY. HOWEVER...NAM/ECMWF SHOW WEAK INSTABILITY WITH COLD
FRONT CROSSING THE AREA DURING THE AFTERNOON. THEREFORE HAVE
INCLUDED SOME LOW POPS AND SLIGHT CHANCE OF THUNDER ACROSS MAINLY
CENTRAL AND NORTHWEST AREAS SUNDAY AFTERNOON. THIS SHORTWAVE THEN
DIGS ACROSS GREAT LAKES REGION WHILE RIDGE BUILDS ACROSS WESTERN
CONUS BY MONDAY. THIS MORE AMPLIFIED PATTERN CONTINUES WITH LONG
WAVE TROUGH MOVING INTO THE WEST ON TUESDAY. AT THIS POINT MODEL
DIFFERENCES BEGIN TO INCREASE WITH PROGRESSION OF UPPER LOW TO
APPROXIMATELY MONTANA BY 00Z THU...WHERE 00Z GFS CUTS OFF LOW WHILE
00Z ECMWF AND GFS ENSEMBLES ARE IN BETTER AGREEMENT WITH AN OPEN
TROUGH. REGARDLESS OF THESE DIFFERENCES...OVERALL PATTERN SUPPORTS
HIGHER POPS BEGINNING TUESDAY NIGHT. SOME QUESTION ABOUT EXTENT OF
INSTABILITY WITH GFS/ECMWF SHOWING VERY WEAK INSTABILITY NUDGING
INTO ND WEDNESDAY. GIVEN MODEL DIFFERENCES AND RUN/RUN
CHANGES...TAPERED DOWN ON THUNDER CHANCES BUT DID NOT REMOVE
ENTIRELY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 627 AM CDT FRI APR 18 2014

VFR CONDITIONS EXPECTED THROUGH THE FORECAST PERIOD. WILL SEE
INCREASING SOUTHEAST WINDS THROUGH THE MORNING...WITH THE
STRONGEST WINDS OVER CENTRAL AND EASTERN NORTH DAKOTA DURING THE
DAY AND EVENING FRIDAY...WITH SUSTAINED WINDS AROUND 25-30 MPH
AND GUSTS TO NEAR 40 MPH. WINDS WILL BEGIN TO DIMINISH OVER THE
WEST FRIDAY AFTERNOON AS LOW PRESSURE APPROACHES. LIGHT RAIN
NORTHWEST THIS MORNING...WITH BETTER PRECIPITATION CHANCES
DEVELOPING WEST FRIDAY DAYTIME SPREADING EAST FRIDAY EVENING.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 10 AM THIS MORNING TO 7 PM CDT THIS EVENING
FOR NDZ003>005-011>013-021-022-035.

WIND ADVISORY FROM 10 AM THIS MORNING TO 10 PM CDT THIS EVENING
FOR NDZ023-025-036-037-047-048-050-051.

&&

$$

UPDATE...JNS
SHORT TERM...NH
LONG TERM...JNS
AVIATION...NH