Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 232003
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
303 PM CDT THU APR 23 2015

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 303 PM CDT THU APR 23 2015

SHOWERS THIS AFTERNOON THROUGH TONIGHT HIGHLIGHT THE SHORT TERM
FORECAST.

OUTSIDE OF THE HIGHWAY 200 CORRIDOR...THE MAJORITY OF
PRECIPITATION IS NOT REACHING THE GROUND DUE TO DRY AIR IN THE
SUB-800 MB LAYER. THE 16-18 UTC HRRR ITERATIONS HAVE THE BEST
HANDLING OF THE ONGOING PRECIPITATION...ESPECIALLY THAT WHICH IS
REACHING THE GROUND...AND WILL WEIGH HEAVILY ON THEIR SOLUTIONS
THROUGH AFTERNOON AND EVENING. THEREAFTER...THE 12 AND INCOMING 18
UTC GLOBAL AND HIGH RESOLUTION SUITES ARE IN AGREEMENT ON ELEVATED
SHOWERS DEVELOPING TONIGHT ACROSS THE JAMES AND INTO THE RED RIVER
VALLEYS BY 05 UTC WITH A MODEST LOW LEVEL JET AHEAD OF THE
SURFACE LOW ACROSS WESTERN SOUTH DAKOTA. GIVEN MARGINALLY POSITIVE
SHOWALTER VALUES...WILL NOT PUT IN THUNDER AT THIS TIME. FRIDAY
APPEARS TO BE DRY ACROSS WESTERN AND CENTRAL NORTH DAKOTA BETWEEN
THE STRONGER LOW ACROSS THE CENTRAL PLAINS AND THE PACIFIC
NORTHWEST TROUGH.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 303 PM CDT THU APR 23 2015

A SPLIT FLOW THROUGH THE WEEKEND WITH PERIODS OF INTERACTION
BETWEEN THE SOUTHERN STREAM AND NORTHERN STREAM. THIS WILL
ULTIMATELY SET UP AN INCREASINGLY WET/UNSETTLED WEATHER PATTERN
THROUGH EARLY NEXT WEEK. TWO MAIN SHORTWAVES TO PUSH ACROSS WESTERN
AND CENTRAL NORTH DAKOTA FRIDAY NIGHT THROUGH MONDAY. THE LATEST
ECMWF IS ADVERTISING A MORE CONTINUOUS RAIN OVER THE WEEKEND INTO
MONDAY...WHILE THE GFS/CANADIAN GEM HAS A MORE DISTINCT START/END
TIME WITH EACH WAVE. UTILIZED A BLEND OF THE ABOVE MODELS ABOVE.
EXPECT A BRIEF DRYING AND WARMING TREND BY MIDWEEK...THEN A
PROGRESSIVE AND POSSIBLY UNSETTLED WEATHER PATTERN SETTING UP LATE
IN THE EXTENDED.

FOR FRIDAY NIGHT THROUGH SATURDAY...A TRANSITORY 700MB-500MB RIDGE
DEVELOPS OUT AHEAD OF AN APPROACHING SHORTWAVE TROUGH SLIDING INTO
THE NORTHERN ROCKIES. THIS SHOULD KEEP CONDITIONS DRY FOR MOST AREAS
FRIDAY NIGHT BEFORE EAST TO SOUTHEAST WINDS ADVECT AN AREA OF
MOISTURE INTO THE WEST. THIS MOISTURE WILL CONVERGE INTO AN
APPROACHING SURFACE COLD FRONT IN EASTERN MONTANA. THUS POPS BECOME
LIKELY THEN CATEGORICAL SATURDAY IN THE WEST...WITH DRIER CONDITIONS
IN THE EAST AS MID LEVEL RIDGING REMAINS INTACT UNTIL 00Z SUNDAY.

SATURDAY NIGHT THROUGH MONDAY NIGHT...AS MENTIONED ABOVE THERE ARE
DIFFERENCES IN THE ECMWF AND GFS/GEM...ESPECIALLY SATURDAY NIGHT
THROUGH SUNDAY. PER GFS/GEM...THE SURFACE LOW/COLD FRONT AND SHORTWAVE
MOVE INTO SOUTHERN CANADA WITH SHOWERS DIMINISHING SATURDAY NIGHT
INTO SUNDAY. THE TRAILING COLD FRONT STALLS UNDER A SOUTHWEST FLOW
ALOFT...WITH LOW LEVEL SOUTH TO SOUTHEAST WINDS FEEDING MOISTURE
INTO NORTH DAKOTA. THE GFS/GEM MODELS TREND TOWARD A CESSATION TO
THE PRECIPITATION UNTIL SUNDAY NIGHT WHEN THE THE FRONT BECOMES
RE-ENERGIZED AS THE NEXT SHORTWAVE TROUGH APPROACHES. WITH THE
SURFACE COLD FRONT AND SOUTHERN STREAM MOISTURE ALREADY IN
PLACE...THIS SETS THE STAGE FOR A MORE WIDESPREAD PRECIPITATION
EVENT SUNDAY NIGHT THROUGH MONDAY. AS MENTIONED ABOVE THE LATEST
ECMWF REALLY DOES NOT STOP THE PRECIPITATION WITH THE INITIAL
SHORTWAVE...RATHER KEEPS THE SURGE MAINLY CONTINUOUS IN THE WEST AND
SLOWLY SPREADS IT EAST AND NORTH THROUGH MONDAY. TOTAL PRECIPITATION
AMOUNTS COULD RANGE BETWEEN A HALF INCH TO ONE INCH IN THE WEST TO
AROUND A QUARTER OF AN INCH IN CENTRAL NORTH DAKOTA THROUGH MONDAY NIGHT.

MONDAY NIGHT THROUGH THURSDAY...GOOD AGREEMENT THAT PRECIPITATION
WILL BE EAST OF THE JAMES RIVER VALLEY BY 12Z TUESDAY FOLLOWED BY
UPPER RIDGING TUESDAY AND WEDNESDAY. WARM AIR ADVECTION RAMPS UP
LATE TUESDAY INTO WEDNESDAY...AHEAD OF AN ADVANCING COLD FRONT WHICH
IS FORECAST TO CROSS SOUTHERN CANADA WEDNESDAY AFTERNOON/EVENING. THE GFS
SHOWS SOME LIGHT PRECIPITATION DEVELOPING IN THE NORTH BEHIND THE
FRONT WEDNESDAY AFTERNOON. THE ECMWF IS ABOUT 6HRS SLOWER WITH THE
COLD FRONT...NOT ARRIVING INTO THE NORTHWEST UNTIL AROUND 00Z
THURSDAY. THURSDAY LOOKS DRY...ALTHOUGH THIS MAY BE BRIEF AS
THE NEXT SYSTEM IS ALREADY APPROACHING THURSDAY NIGHT INTO FRIDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT |247 PM CDT THU APR 23 2015

SCATTERED RAIN SHOWERS ACROSS WESTERN AND CENTRAL NORTH DAKOTA
THIS AFTERNOON WILL CONTINUE TO MOVE EAST AND FADE WITH
SUNSET...BEFORE ADDITIONAL SHOWERS FORM TONIGHT NEAR KJMS AFTER 05
UTC. MVFR CONDITIONS IN RAIN POSSIBLE. OTHERWISE...VFR CONDITIONS
FOR THE 18 UTC CYCLE.

&&

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

$$

SHORT TERM...AYD
LONG TERM...KS
AVIATION...AYD




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