Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 291541
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
941 AM CST MON DEC 29 2014

.UPDATE...
ISSUED AT 941 AM CST MON DEC 29 2014

THE ONLY UPDATE TO THE FORECAST WAS TO CLOUD COVER AS IT IS MOVING
OUT OF THE SOUTHWEST SLOWER THAN ANTICIPATED. ALSO ADDED IN SOME
CLOUD COVER ACROSS MORTON...OLIVER...AND MERCER COUNTIES DUE TO
STEAM FROM THE POWER PLANTS. OTHERWISE THE PREVIOUS FORECAST IS ON TRACK.

UPDATE ISSUED AT 644 AM CST MON DEC 29 2014

THE PREVIOUS FORECAST IS ON TRACK. SURFACE OBSERVATIONS CONFIRM
THAT SNOW HAS MOVED INTO SOUTH DAKOTA AS FORECAST. FRIGID WIND
CHILLS WILL DOMINATE THE WEATHER STORY FOR THE NEXT COUPLE DAYS.

&&

.SHORT TERM...(TODAY AND TONIGHT)

ISSUED AT 340 AM CST MON DEC 29 2014

FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE LINGERING
SNOW ACROSS THE SOUTHWEST CORNER EARLY THIS MORNING AND VERY COLD
TEMPERATURES THROUGH THE PERIOD.

CURRENTLY...LONG WAVE TROUGH OVER NORTH AMERICAN ALLOWING COLD
ARCTIC AIR TO ENCOMPASS THE ENTIRE NORTHERN PART OF THE UNITED
STATES. SURFACE HIGH PRESSURE RIDGE EXTENDS NORTHWEST TO SOUTHEAST
ACROSS THE NORTHERN PLAINS...WITH THE RIDGE AXIS STRETCHED FROM
SOUTHERN SASKATCHEWAN SOUTHEAST THROUGH NORTHWEST AND CENTRAL
NORTH DAKOTA. OVERRUNNING EASTERLY LOW LEVEL FLOW WEST AND SOUTH
OF THE SFC RIDGE CONTINUES TO GENERATE LIGHT SNOW OVER
SOUTHWESTERN NORTH DAKOTA. EXPECT THE SNOW TO MOVE OFF TO OUR
SOUTH BY 12Z AS THIS FORCING DIMINISHES OVER NORTH DAKOTA ALONG
WITH CLOUDS DECREASING THROUGH 15Z NORTH TO SOUTH.

COLD HIGH PRESSURE CURRENTLY CENTERED OVER CENTRAL ALBERTA WILL
SLOWLY MOVE SOUTH INTO MONTANA TODAY INTO TONIGHT. AHEAD OF THE
HIGH PRESSURE...CAA AND PRESSURE RISES MAINTAIN A STEADY NORTHWEST
WIND TO AROUND 10KTS THROUGH THE PERIOD. FORECAST TEMPERATURES
COUPLED WITH THE WIND SUPPORTS CURRENT WIND CHILL HEADLINES THIS
MORNING AND INTO TUESDAY.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 325 AM CST MON DEC 29 2014

THE SHORT TERM WIND CHILL THREAT WILL CONTINUE THROUGH MIDDAY
TUESDAY...WITH A FEW HOURS OF NEAR ADVISORY CRITERIA EXPECTED
IN THE JAMES RIVER VALLEY ON WEDNESDAY MORNING. WITH THE MARGINAL
VALUES FORECAST...THERE IS NO REASON TO EXTEND THE CURRENT WIND
CHILL ADVISORY INTO WEDNESDAY MORNING AT THIS TIME...THOUGH THIS
WILL NEED TO BE WATCHED AS THE FORECAST IS REFINED.

THE MAIN WEATHER STORY THEREAFTER IS THE EVOLVING ACTIVE PATTERN
THAT STARTS WITH THE PREVIOUSLY ADVERTISED THURSDAY/FRIDAY SNOW
POSSIBILITY. NOW...MODELS/ENSEMBLES CALL FOR SEVERAL WEAKER WAVES
EMBEDDED IN NORTHWEST FLOW ALOFT TO PASS THROUGH NORTH DAKOTA.

THERE IS GREAT UNCERTAINTY WITH TIMING AND AMOUNTS. UNCERTAINTY GROWS
WITH FORECAST HOUR...AND THE DIFFERENCE IS BEST ILLUSTRATED BY THE
SUNDAY NIGHT FORECAST. IN THE 00 UTC GFS...THERE IS A 1050 HPA
SURFACE HIGH OVER THE SOURIS BASIN. IN THE 00 UTC ECMWF...THERE IS A
1011 HPA SURFACE LOW OVER GRASSY BUTTE WITH 4-6 INCHES OF SNOW OVER
PARTS OF THE SOURIS BASIN.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 644 AM CST MON DEC 29 2014

ARCTIC HIGH PRESSURE WILL MOVE SOUTHEAST ACROSS NORTH DAKOTA
RESULTING IN VFR CONDITIONS AT ALL TERMINALS TODAY INTO TONIGHT.


&&

.BIS WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY UNTIL NOON CST /11 AM MST/ TUESDAY FOR
NDZ001>005-009>013-017>023-025-031>037-042-045>048-050-051.

WIND CHILL ADVISORY FROM 5 PM THIS AFTERNOON TO 11 AM MST
TUESDAY FOR NDZ040-041-043-044.

&&

$$

UPDATE...MM
SHORT TERM...NH
LONG TERM...SCHECK
AVIATION...NH





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