Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 220238
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
938 PM CDT THU MAY 21 2015

.UPDATE...

ISSUED AT 938 PM CDT THU MAY 21 2015

NO UPDATES WITH THE MID EVENING FORECAST ISSUANCE.


UPDATE
ISSUED AT 622 PM CDT THU MAY 21 2015

SUBTLE FRONTAL BOUNDARY ACROSS NORTHWEST INTO SOUTH CENTRAL NORTH
DAKOTA WILL SLOWLY ERODE/MIGRATE BACK EAST TONIGHT AS A MID LEVEL
RIDGE BUILDS INTO THE REGION. A MOSTLY CLEAR SKY WITH LOW
TEMPERATURES OVERNIGHT IN THE LOW TO MID 40S. OVERALL CHANGES
WERE MINIMAL WITH MAIN EDITS TO TWEAK NEAR TERM SKY COVER A BIT.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 343 PM CDT THU MAY 21 2015

THE H500 RIDGE OF THE NORTHERN PORTION OF A REX BLOCK WILL REMAIN
IN PLACE FOR ANOTHER DAY ACROSS NORTH DAKOTA RESULTING IN QUIET
AND MAINLY CLEAR WEATHER TONIGHT AND MOSTLY SUNNY CONDITIONS FRIDAY.
AS THE DAY PROGRESSES FRIDAY THE SOUTHWEST US UPPER LOW BEGINS TO
KICK OUT AND SEND SOME SHORTWAVE RIPPLES NORTHEAST INTO THE PLAINS
STATES. MODELS THEN BREAK DOWN THE RIDGE OVER THE NORTHERN PLAINS
FOR THE WEEKEND. HOWEVER FOR FRIDAY WILL STILL BE DRY. SOME
INCREASING CLOUDS EXPECTED AS A SOUTHEAST WIND COMPONENT WILL
BEGIN TO MOVE HIGHER DEWPOINTS INTO THE REGION. FRIDAYS HIGH WILL
AGAIN BE IN THE 70S EXCEPT THE SOUTHWEST WHERE INCREASING CLOUDS
AND AN H8 THERMAL TROUGH WILL HOLD TEMPS TO THE UPPER 60S.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 343 PM CDT THU MAY 21 2015

AN UNSETTLED PATTERN FOR THE LONG TERM PERIOD WITH CHANCES OF
SHOWERS EACH DAY. THE BEST CHANCES OF RAIN OVER WESTERN AND CENTRAL
NORTH DAKOTA WILL BE THIS MEMORIAL DAY WEEKEND.

THE GFS AND ECMWF MODELS CONTINUED TO BE IN GENERAL AGREEMENT WITH
MAIN FEATURES AND RESULTANT TIMING AND AREAL COVERAGE OF RAINFALL.
THE NAM WAS AGAIN THE OUTLIER AND GENERAL CONSENSUS WAS TO DOWNPLAY
THE NAM.

THE LARGE LONGWAVE TROUGH OVER THE WEST COAST AND ROCKIES TODAY IS
FORECAST TO MOVE EAST ACROSS THE ROCKIES...INTENSIFY...EMERGE
INTO THE PLAINS...THEN LIFT GRADUALLY NORTHEAST BY THE MIDDLE OF
NEXT WEEK.

BEGINNING LATE FRIDAY NIGHT THE MODELS DEPICT THE FIRST OF MANY
UPPER LEVEL SHORTWAVE IMPULSES MOVING NORTHWARD THROUGH THE LONGWAVE
TROUGH THAT SHOULD REACH NORTH DAKOTA. NORTH DAKOTA SHOULD REMAIN ON
THE NORTH SIDE OF ANY RESULTANT SURFACE LOWS...NAMELY SATURDAY AND
SATURDAY NIGHT. ON SUNDAY THERE IS A HINT THAT THE NORTHERN
EXTENSION OF AN INVERTED LOW OVER THE EASTERN SIDE OF SD/NE/KS MAY
NUDGE NORTHWARD INTO EASTERN NORTH DAKOTA. THE MODELS ARE HINTING AT
LARGER CAPE AND STRONGER BULK SHEAR ON SUNDAY FOR CENTRAL INTO
EASTERN NORTH DAKOTA. THIS MAY BE A DAY OF SOME SEVERE STORMS...BUT
WE WILL HAVE TO SEE HOW THE NEXT COUPLE OF MODEL RUNS HANDLE THE
ENERGY AND SHEAR ASSOCIATED WITH THIS SYSTEM.

ON MONDAY THE SYSTEM SHOULD BE LIFTING NORTHEAST INTO THE CENTRAL
AND NORTHERN PLAINS...AND BEGINNING TO EXIT THE REGION MONDAY NIGHT.

3-DAY RAINFALL TOTAL ESTIMATES FOR SATURDAY THROUGH MEMORIAL DAY
RANGE FROM 0.75 TO 1.25 INCHES ACROSS SOUTHWESTERN AND SOUTH
CENTRAL NORTH DAKOTA...TO 0.25 TO 0.75 INCHES ACROSS THE NORTHWEST
AND NORTH CENTRAL.

ANOTHER SHORTWAVE DEVELOPS IN THE UPPER LEVEL WESTERLIES FOLLOWING
THIS LARGE SYNOPTIC SYSTEM. THIS WILL KEEP CHANCES OF SHOWERS OVER
WESTERN AND CENTRAL NORTH DAKOTA.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)

ISSUED AT 622 PM CDT THU MAY 21 2015

CONDITIONS WILL REMAIN DRY AND VFR THROUGH THE 00Z TAF FORECAST.


&&

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

$$

UPDATE...NH
SHORT TERM...WAA
LONG TERM...JV
AVIATION...NH


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