Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 262124
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
324 PM CST WED NOV 26 2014

.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 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 321 PM CST WED NOV 26 2014

A WINTRY MIX OF SNOW...SLEET AND FREEZING RAIN WILL BEGIN TO
IMPACT WESTERN NORTH DAKOTA THURSDAY. UNTIL THEN ARCTIC HIGH
PRESSURE ACROSS SASKATCHEWAN WILL MAINTAIN VFR CONDITIONS FROM
KISN-KMOT-KBIS-KJMS THROUGH 10Z. AFTER 10Z LIGHT SNOW WILL SPREAD
NORTHEAST ACROSS THE REGION...BEGINNING WITH KDIK FIRST THEN
REACHING A KISN-KBIS LINE AFTER 12Z WITH ASSOCIATED MVFR
CONDITIONS...WITH IFR AT KDIK. THE THREAT FOR FREEZING RAIN OR
SLEET WILL INCREASE FROM KDIK-KBIS MAINLY AFTER 18Z THURSDAY.

&&

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

WINTER WEATHER ADVISORY FROM NOON THURSDAY 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.

&&

$$

SHORT TERM...WAA
LONG TERM...SCHECK
AVIATION...WAA







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