Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 270555
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1255 AM CDT WED APR 27 2016

.UPDATE...
ISSUED AT 1237 AM CDT WED APR 27 2016

LATEST SATELLITE AND RADAR IMAGERY SHOWS UPPER LOW OVER NORTHEAST
WYOMING CONTINUES TO PULL MOISTURE RESULTING IN RAIN AND SNOW
SHOWERS INTO CONTINUES TO BE PULLED INTO SOUTH CENTRAL AND WESTERN
NORTH DAKOTA. THE PRECIPITATION CURRENTLY IS A LITTLE MORE SPOTTY
IN NATURE...ESPECIALLY AS YOU HEAD MORE EAST AND NORTH...SO
LOWERED QPF AMOUNTS IN THE 06-12 UTC TIMEFRAME. WITH CURRENT
TEMPERATURES RIGHT AROUND FREEZING OVER A GOOD PORTION OF THE
SOUTHWEST...THIS STILL MAY YIELD SOME SNOW ACCUMULATIONS OF A HALF
INCH TO AND INCH LATE TONIGHT THROUGH WEDNESDAY MORNING FROM
AROUND GRASSY BUTTE THROUGH DICKINSON AND GLEN ULLIN TO MOTT AND
NORTHERN GRANT COUNTY. ALSO ADJUSTED POPS A LITTLE FARTHER WEST
WEDNESDAY MORNING PER LATEST GLOBAL AND MESOSCALE MODEL RUNS. THIS
PLACES THE HIGHEST POPS MAINLY ALONG AND WEST OF THE MISSOURI
RIVER WEDNESDAY MORNING...BUT EXTENDING EASTWARD INTO EMMONS AND
POSSIBLY LOGAN AN MCINTOSH COUNTIES ALONG THE SOUTH DAKOTA BORDER.

UPDATE ISSUED AT 923 PM CDT TUE APR 26 2016

AREAS OF LIGHT RAIN AND SNOW CONTINUE TO LIFT THROUGH SOUTHWEST
NORTH DAKOTA. PREVIOUS FORECAST ADDRESSED THIS RATHER WELL...AND
MINIMAL UPDATES ARE NEEDED.

UPDATE ISSUED AT 638 PM CDT TUE APR 26 2016

RAIN SHOWERS STARTING TO LIFT INTO FAR SOUTHWESTERN NORTH DAKOTA
SO HAVE INCREASED PRECIPITATION CHANCES OVER THAT AREA A BIT
EARLIER THAN PREVIOUSLY FORECAST. HAVE ALSO PUT THE MENTION OF FOG
IN OVER MUCH OF THE WEST...PARTICULARLY OVER THE HIGHER TERRAIN
WHERE VISIBILITIES ARE STARTING TO DIP DOWN. UPDATES HAVE BEEN
SENT.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 408 PM CDT TUE APR 26 2016

RAIN AND SNOW CHANCES TONIGHT AND WEDNESDAY ARE THE FOCUS OF THE
SHORT TERM FORECAST.

FIRST OF ALL...THUS FAR TODAY PRECIPITATION OVER WESTERN SD HAS
HAD A DIFFICULT TIME MAINTAINING ITS INTENSITY AS IT APPROACHES
ND. RADAR ANIMATIONS THROUGH 2105 UTC SUGGEST THIS TREND MAY NOT
REVERSE ITSELF FOR A WHILE...RENDERING MOST HIGH-RESOLUTION MODEL
GUIDANCE TOO QUICK TO SPREAD PRECIPITATION NORTH AND EAST ACROSS
THE AREA THIS EVENING. WE THEREFORE SLOWED THE DEVELOPMENT AND
ARRIVAL OF PRECIPITATION CHANCES COMPARED TO THAT GUIDANCE AND TO
THE PRIOR FORECAST.

AFTERNOON SATELLITE IMAGERY REVEALS A RELATIVELY STRONG SHORTWAVE
TROUGH CROSSING THE TX PANHANDLE. THIS WAVE IS EXPECTED TO CLOSE
OFF AT 500 MB BY THE TIME IT REACHES NEB BY MIDDAY WEDNESDAY. WE
EXPECT THE DEEPENING SOUTHEAST FETCH OF MOISTURE TO THE NORTH OF
THAT LOW AND ASSOCIATED QG FORCING ALOFT TO BRING ANOTHER ROUND
OF PRECIPITATION TO WESTERN AND SOUTH CENTRAL ND BEGINNING LATE
TONIGHT...AND PEAKING WEDNESDAY AND WEDNESDAY EVENING. THE MAIN
UNCERTAINTY WITH THIS EVENT IS HOW FAR NORTH THE SHIELD OF RAIN
WILL EXTEND. THE 00...06 AND 12 UTC NAM ITERATIONS WERE FURTHEST
NORTH WITH THE PRECIPITATION SHIELD INTO THE MINOT AREA...WHILE
THE 12 UTC GFS AND ECMWF FOCUS THE PRECIPITATION ALONG AND SOUTH
OF A LINE FROM WILLISTON TO BISMARCK. WE RELIED ON A MULTI-MODEL
BLEND OF GUIDANCE TO CONSTRUCT THE FORECAST GIVEN THE UNCERTAINTY
AND THE FACT THAT THE PV ANOMALIES /QG FORCING/ THAT WILL CAUSE
THE PRECIPITATION MAY BE IMPACTED BY DEEP CONVECTION IN KS AND
NEB THROUGH TONIGHT...POTENTIALLY ALTERING THEIR INTENSITY AND
PATH. HOWEVER...IT IS WORTH NOTING THAT THE JUST-ARRIVING 18 UTC
NAM HAS FALLEN IN LINE WITH THE REST OF THE GLOBAL MODELS WITH AN
AXIS OF PRECIPITATION CENTERED FROM WESTERN TO SOUTH CENTRAL ND.

NOTE THAT WE DO HAVE A MIX OF RAIN AND SNOW IN THE FORECAST FOR
WESTERN ND TONIGHT...AND SOUTHWEST ND WEDNESDAY...PER MODEL 850 MB
TEMPERATURES AND NCEP DOMINANT PRECIPITATION-TYPE OUTPUT APPLIED
TO THE GFS AND NAM MASS FIELDS.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 408 PM CDT TUE APR 26 2016

RAIN AND SNOW WILL LIKELY CONTINUE WEDNESDAY NIGHT AND DIMINISH ON
THURSDAY. APPLYING A MULTI-MODEL...MULTI-METHOD SNOW-TO-LIQUID
RATIO TECHNIQUE TO THE 12 UTC MODEL-AVERAGED QPF YIELDED SNOWFALL
OF 1 TO 2 INCHES IN SOUTHWEST ND WEDNESDAY NIGHT.

OTHERWISE...IT WILL REMAIN SEASONABLY COOL AND MOSTLY CLOUDY ALL
THE WAY THROUGH THE WEEKEND WHILE A MEAN WESTERN UNITED STATES
TROUGH REMAINS IN PLACE. THE NEXT POTENTIAL RAIN-MAKER MAY STILL
ARRIVE SATURDAY AND SUNDAY AS ANOTHER VIGOROUS 500-MB LOW EJECTS
ACROSS THE CENTRAL PLAINS. THE NORTHERN EXTENT OF PRECIPITATION
ASSOCIATED WITH THAT WAVE IS STILL UNCERTAIN. CASE IN POINT...THE
00 UTC GUIDANCE GENERALLY SUGGESTED A WETTER SCENARIO ACROSS ND
WHILE THE 12 UTC GFS AND ECMWF BOTH PEELED BACK THEIR QPF FOR THE
AREA.

BY THE EARLY TO MIDDLE PART OF NEXT WEEK...MODEL GUIDANCE HAS BEEN
CONSISTENT IN SUGGESTING THE LARGE-SCALE BLOCKING PATTERN THAT HAS
BEEN IN PLACE FOR SOME TIME /AND THE RESULTANT MEAN TROUGHING OVER
THE WESTERN UNITED STATES/ WILL FINALLY BREAK DOWN. THE RESULT MAY
BE A WARMING AND DRYING TREND. THE MULTI-MODEL BLEND THAT WE RELY
ON FOR THE LONG TERM FORECAST CALLS FOR HIGHS BACK INTO THE 60S F
MONDAY AND TUESDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1237 AM CDT WED APR 27 2016

WIDESPREAD IFR CEILINGS EXPECTED TO CONTINUE OVER SOUTHWEST AND
SOUTH CENTRAL NORTH DAKOTA THROUGH THE EARLY MORNING HOURS
INCLUDING KDIK AND KBIS. AREAS OF FOG ALSO AT KDIK AND KBIS.
MAINLY SNOW AT KDIK WITH VISIBILITIES UNDER A MILE AT TIMES.
PRECIPITATION EXPECTED TO REMAIN ALL RAIN AT KBIS. CONDITIONS WILL
SLOWLY IMPROVE WEDNESDAY AFTERNOON. FARTHER NORTH AND EAST...IFR
TO MVFR CONDITIONS AT KISN THROUGH WEDNESDAY MORNING...THEN
IMPROVING. MAINLY VFR CONDITIONS AT KMOT AND KJMS THROUGH THE 06Z
TAF PERIOD...BUT OCCASIONAL MVFR CEILINGS POSSIBLE...ESPECIALLY AT
KJMS FROM 12-18 UTC WEDNESDAY.

&&

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

$$

UPDATE...TWH
SHORT TERM...CJS
LONG TERM...CJS
AVIATION...TWH



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