Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 262108
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
408 PM CDT TUE APR 26 2016

.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 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 408 PM CDT TUE APR 26 2016

WIDESPREAD MVFR TO IFR CEILINGS AND VISIBILITIES OVER SOUTHWEST
AND SOUTH CENTRAL NORTH DAKOTA THROUGH TONIGHT. THERE HAS BEEN A
SHARP CUTOFF TO LOW VFR CEILINGS FROM NEAR KISN TO KMOT...MAKING
FOR A DIFFICULT AND LOWER-CONFIDENCE FORECAST AT THOSE TERMINALS
TODAY. THE SAME SITUATION MAY OCCUR AGAIN TONIGHT IN THAT
CORRIDOR.

&&

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

$$

SHORT TERM...CJS
LONG TERM...CJS
AVIATION...NH



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