Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 270639
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1239 AM CST THU NOV 27 2014

.UPDATE...
ISSUED AT 1239 AM CST THU NOV 27 2014

THE ARCTIC HIGH PRESSURE CENTER WAS OVER THE RED RIVER VALLEY OF
NORTH DAKOTA AND MINNESOTA. CLEAR SKIES OVER THE EASTERN HALF OF
NORTH DAKOTA WITH LIGHT WINDS HAS ALLOWED TEMPERATURES TO PLUMMET
WELL BELOW ZERO. SEVERAL SITES REPORTING 20-25 BELOW ZERO FROM THE
MINOT AFB TO THE JAMES VALLEY. LARGE TEMPERATURE GRADIENT GOING WEST
AS CLOUDS MOVE/DEVELOP EASTWARD. BISMARCK WAS AT -11 UNDER CLEAR TO
PARTLY CLOUDY SKIES...BUT MANDAN ALREADY HAD THE LOW CLOUDS AND WAS
AT -2. THE FAR SOUTHWEST SITES WERE REPORTING THE TEENS ABOVE ZERO.
SOME WIND CHILLS STILL AT -25 TO -39 WITH LIGHT EAST OR SOUTH WINDS
OF 5 TO 8 MPH. THE PREVIOUS ISSUANCE OF A SPECIAL WEATHER STATEMENT
HAS ADDRESSED THIS. RADAR RETURNS INDICATE EITHER VIRGA OR LIGHT
SNOW IN THE BOWMAN AREA...BUT NO SITES REPORTING LIGHT SNOW JUST
YET.

ASIDE FROM LOWERING MINIMUM TEMPERATURES EXPECTED THIS MORNING...THE
FORECAST REMAINS ON TRACK.

UPDATE ISSUED AT 1000 PM CST WED NOV 26 2014

DANGEROUS WIND CHILLS HAVE DEVELOPED ACROSS NORTH CENTRAL NORTH
DAKOTA INTO THE JAMES RIVER BASIN. THE 9 PM CST OBSERVATION AT THE
MINOT AFB WAS A WIND CHILL OF 39 BELOW ZERO. AREAS TOWARDS THE
TURTLE MOUNTAIN REGION SOUTH INTO THE JAMES RIVER BASIN WERE ALSO
REPORTING WIND CHILLS AROUND 30 BELOW ZERO AS OF THIS WRITING.

CLOUD COVER OVER WESTERN NORTH DAKOTA IS BEGINNING TO LIFT NORTH
INTO CENTRAL NORTH DAKOTA...AND SHOULD EVENTUALLY GET INTO
EASTERN NORTH DAKOTA LATER TONIGHT. DUE TO THE EXPECTED INCREASE
IN CLOUD COVER...THESE WIND CHILLS SHOULD ONLY LAST FOR THE NEXT
THREE TO SIX HOURS.

GIVEN THE EXPECTED SHORT DURATION OF THESE WIND CHILLS...DECIDED
TO HANDLE THIS SITUATION WITH AN SPS FOR NOW. A WIND CHILL
ADVISORY WOULD ALSO CLUTTER THE CURRENT WSW FOR THE FREEZING RAIN
ADVISORY/WINTER WEATHER ADVISORY FOR THURSDAY.

UPDATE ISSUED AT 552 PM CST WED NOV 26 2014

NO MAJOR UPDATES WERE REQUIRED TO THE ONGOING FORECAST. THE MAIN
FORECAST PROBLEM WILL BE JUST HOW LOW TEMPERATURES WILL GET EAST
OF THE MISSOURI RIVER THIS EVENING BEFORE INCREASING CLOUD COVER
TAKES OVER AFTER MIDNIGHT.

JAMESTOWN DROPPED FROM ONE DEGREE TO 6 BELOW ZERO OVER THE LAST
HOUR. THE FORECAST LOW OF 12 BELOW ZERO LOOKS TO BE ON TARGET FOR
NOW...BUT MAY NEED TO BE LOWERED BASED ON EVENING OBS/TRENDS.
BOTTOM LINE...IT WILL BE COLD TONIGHT. AT LEAST THE WINDS WILL BE
RELATIVELY LIGHT.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 321 PM CST WED NOV 26 2014

THE FORECAST ISSUE TODAY WILL CENTER ON FREEZING RAIN/SLEET
ACROSS SOUTHWEST THROUGH THE WEST CENTRAL THURSDAY AND SNOW
ACCUMULATIONS NORTH CENTRAL NIGHT. SURFACE ARCTIC HIGH PRESSURE
CENTERED OVER MANITOBA INTO THE EASTERN DAKOTAS TONIGHT WILL SET
UP A GOOD OVERRUNNING MIXED PRECIPITATION EVENT ON THANKSGIVING
DAY INTO THE EVENING. THE SHALLOW ARCTIC AIR WILL BE ERODED
SOUTHWEST DURING THE DAY AS THE WARM FRONT APPROACHES AND MOVE
NORTH SO EXPECT A BRIEF PERIOD OF FREEZING RAIN SOUTHWEST BETWEEN
SUNRISE AND NOON. THEN THE MOST FAVORABLE AREA FOR FREEZING RAIN
EXTENDS FROM JUST SOUTH OF WILLISTON SOUTHEAST THROUGH GRANT
AND SIOUX COUNTIES. THE TIMING OF THIS AREA WILL BE FROM NOON
UNTIL THE EVENING HOURS. MEANWHILE...COLDER AIR OVER THE NORTH
WILL ASSURE THE PRECIPITATION IS SNOW...WITH 3 TO 4 INCHES EXPECTED
BY FRIDAY MORNING. FOR THIS A FREEZING RAIN ADVISORY HAS BEEN
ISSUED SOUTHWEST...AND A WINTER WEATHER ADVISORY NORTH FOR SNOW.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 321 PM CST WED NOV 26 2014

THE MAIN FORECAST PROBLEM TODAY IS THE POTENTIAL FOR A WINTRY MIX
ACROSS WESTERN NORTH DAKOTA ON FRIDAY.

12 UTC GFS/ECMWF/NAM/GEM GLOBAL ARE IN GOOD AGREEMENT THAT THE
AFOREMENTIONED WARM FRONT WILL BE STRETCHED ACROSS NORTHERN NORTH
DAKOTA AT THE START OF THE PERIOD. IT APPEARS THAT THE MAIN PUSH OF
COLD AIR ADVECTION WILL NOT REACH NORTH DAKOTA UNTIL LATE FRIDAY
EVENING...BASED ON MODEL CONSENSUS. THUS...ISENTROPIC LIFT AND A
SUFFICIENTLY STRONG MELTING LAYER ALOFT JUSTIFY KEEPING A WINTRY MIX
IN PLACE ACROSS PARTS OF THE WEST UNTIL COLD AIR ADVECTION WASHES
OUT THE MELTING LAYER.

THEREAFTER...THERE IS GOOD AGREEMENT AMONG 12 UTC ECMWF/GFS/GEM
GLOBAL AND 06 UTC GEFS THAT QUASI-ZONAL UPPER LEVEL FLOW WILL
TRANSITION TO A MORE AMPLIFIED PROGRESSIVE PATTERN. VERY LIGHT MODEL
QPF AND TIMING ISSUES MAKE CHANCES OF PRECIPITATION VERY SMALL WHEN
BLENDING...THOUGH THE PATTERN SUGGESTS THAT AT LEAST A COUPLE WAVES
WILL MOVE THROUGH THE REGION AND RESULT IN LIGHT SNOW. SUBSEQUENT
MODEL CYCLES SHOULD PROVIDE MORE CLARITY ON THIS ISSUE.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1239 AM CST THU NOV 27 2014

MVFR CIGS OVER WESTERN NORTH DAKOTA WILL LIFT EAST INTO CENTRAL
NORTH DAKOTA EARLY THIS MORNING...WITH OCNL IFR CIGS. LIGHT SNOW
WILL THEN DEVELOP IN THE WEST THIS MORNING...MAINLY FROM 09Z-12Z AT
KDIK...THEN SPREAD EAST AROUND 18Z. SNOW IS EXPECTED TO CHANGE TO A
WINTRY MIX OVER KDIK THURSDAY AFTERNOON...AND AT KISN/KBIS AROUND
21Z...BUT REMAIN SNOW AT KMOT/KJMS. SEE INDIVIDUAL TAFS FOR TIMING
DETAILS.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
FREEZING RAIN ADVISORY FROM NOON CST /11 AM MST/ TODAY TO
MIDNIGHT CST /11 PM MST/ TONIGHT FOR NDZ017>020-031>034-042-045.

WINTER WEATHER ADVISORY FROM NOON TODAY TO 6 AM CST FRIDAY FOR
NDZ001>005-009>013-021.

FREEZING RAIN ADVISORY FROM 5 AM TO 11 AM MST THURSDAY FOR
NDZ040-041-043-044.

&&

$$

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






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