Cold in North Dakota, December 21 to 22, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
307 PM CST SUN DEC 21 2008

.SYNOPSIS...

A DEEP VORTEX OVER THE NORTH POLE IS CURRENTLY DIVING SOUTHWARD OVER
THE CANADIAN MARITIMES TO RECHARGE THE NEGATIVE HEIGHT ANOMALY JUST
NORTH OF HUDSON BAY. MEANWHILE...A STRONG NORTHEAST PACIFIC LOW IS
PUSHING INTO THE NORTHWEST RIGHT BEHIND THE EXITING UPPER
MIDWEST/GREAT LAKES WINTER STORM. THE MAIN BRANCH OF THE SUBTROPICAL
JET EXTENDS FROM SOUTHERN BAJA MEXICO THROUGH THE SOUTHEAST AND INTO
THE MIDATLANTIC.

MODELS CONTINUE TO INDICATE MAINTENANCE OF THE NORTH AMERICAN MEAN
MIDDLE/UPPER LEVEL TROUGH UNTIL FLOW BECOMES MORE ZONAL IN
ANTICIPATION OF EASTERN PACIFIC AND WESTERN ATLANTIC LOWS FORMING AT
THE BEGINNING OF NEXT WEEK.

&&

.SHORT TERM...SUNDAY THROUGH CHRISTMAS EVE...

WINDS ARE FINALLY WEAKENING THIS AFTERNOON...AND BLOWING SNOW IS
BECOMING LESS OF A PROBLEM. SURFACE OBSERVATIONS ACROSS WESTERN AND
CENTRAL NORTH DAKOTA INDICATE THAT VISIBILITIES ARE GREATER THAN 6
MILES AT ALL STATIONS.

AS SURFACE HIGH PRESSURE SLIDES SOUTHEASTWARD FROM ALBERTA INTO THE
CENTRAL PLAINS...EXPECT CLEAR SKIES AND LIGHT WINDS FOR THE
REMAINDER OF THE SUNDAY. HOWEVER...BY MONDAY MORNING CLOUDS SHOULD
CREEP INTO SOUTHWESTERN NORTH DAKOTA AS MIDDLE LEVEL HEIGHT FALLS
AHEAD OF THE AFOREMENTIONED NORTHWESTERN U.S. STORM SPREAD INTO THE
NORTHERN PLAINS. THIS STORM WILL BE THE MAIN FOCUS FOR THE REMAINDER
OF THE SHORT TERM.

THE ASSOCIATED SURFACE LOW IS FORECAST TO SLIDE SOUTH OF THE STATE
THROUGH SOUTH DAKOTA...WHILE UPPER LEVEL DEFORMATION AND MIDDLE
LEVEL FRONTOGENESIS COMBINE TO SPREAD A WIDE SWATH OF AROUND 2 TO 5
INCHES SNOW. THE EXCEPTION IS NORTHWEST NORTH DAKOTA...WHICH LOOKS
TO MISS SOME OF THE MORE FAVORABLE DYNAMICS. THERE...EXPECT 1 TO 3
INCHES OF NEW SNOW. THE SYSTEM LOOKS TO REMAIN WELL BELOW WINTER
STORM CRITERIA...SO HAVE ELECTED NOT TO ISSUE A WATCH...DESPITE
TREND IN MODELS AND NCEP/HYDROMETEOROLOGICAL PREDICTION CENTER
FORECASTS TOWARD HIGHER AMOUNTS. WITH HOLIDAY TRAVEL A
CONCERN...HAVE STUCK WITH ADVERTISEMENTS IN THE FORM OF A SPECIAL
WEATHER STATEMENT AND TOP NEWS STORY ONLINE.

TEMPERATURES ARE ONCE AGAIN FORECAST TO REMAIN BELOW AVERAGE FOR THE
PERIOD...THOUGH SOME GRADUAL WARMING IS EXPECTED FOR TUESDAY AND
CHRISTMAS EVE. MEANWHILE...WIND CHILL TEMPERATURES ARE LIKELY TO
REMAIN AT OR BELOW WIND CHILL ADVISORY CRITERIA...BUT THE WIND
SPEEDS ARE EXPECTED TO BE BELOW 10 MPH FOR MOST OF THE NIGHT. EXPECT
THAT AS SOUTHEASTERLY WINDS GET GOING MONDAY MORNING THAT WE MAY
NEED A WIND CHILL ADVISORY LEADING UP TO THE INEVITABLE WINTER
WEATHER ADVISORY FOR SNOW LATE MONDAY.

.LONG TERM...THURSDAY (CHRISTMAS DAY) THROUGH SUNDAY NIGHT

WE BEGIN THE EXTENDED PERIOD ON CHRISTMAS DAY WITH A MAJOR LONGWAVE
TROUGH TO OUR WEST OVER THE THE WEST COAST AND MOVING OVER THE
ROCKIES. THE EXTENDED MODELS GENERALLY TAKE THE BULK OF THE ENERGY
WITH THIS SYSTEM AND DIG SOUTHWARD ALONG THE SOUTHERN PLAINS. THE
SURFACE LOW THAT DEVELOPS WITH THIS SYSTEM IS DEVELOPED OVER THE
SOUTHERN/CENTRAL PLAINS AND WILL LIKELY BRING A SMALL CHANCE OF
LIGHT SNOW TO OUR WESTERN COUNTIES ON CHRISTMAS DAY NIGHT (THURSDAY
NIGHT). THE MODELS THEN INDICATE THE STORM SYSTEM MOVING NORTHEAST
TOWARDS THE GREAT LAKES. THE UPPER LEVEL TROUGH ON BOTH THE GFS AND
EUROPEAN MOVE UPPER LEVEL ENERGY ACROSS NORTH DAKOTA...SO KEPT A
SLIGHT CHANCE MENTION OVER US ON FRIDAY.

SATURDAY THE GFS AND EUROPEAN MODELS DIVERGE IN SOLUTIONS...BUT FROM
BOTH DEPICTIONS WE ARE UNDER THE INFLUENCE OF ZONAL FLOW ALOFT
BETWEEN TWO LOWS...ONE IN THE GULF OF ALASKA AND LOWS FROM
NORTHEASTERN CANADA THROUGH THE NORTHEASTERN US - DEPENDING ON WHICH
MODEL IS USED. SUNDAY THE MODELS THREATEN TO PUSH THE FIRST OF A
SERIES OF SHORTWAVES ACROSS THE ROCKIES ALONG THE CANADIAN BORDER
TOWARDS OUR AREA. HOWEVER...TIMING OF THIS ENERGY IS SUSPECT AND
WILL KEEP THE MENTION OF PRECIPITATION OUT OF THE LAST DAY (SUNDAY)
OF THE FORECAST.

A DEFINITE WARMING TREND TOWARDS THE MIDDLE AND END OF THIS WEEK
WITH HIGHS GENERALLY FROM 5 TO 20 ABOVE.

&&

.AVIATION...

ARCTIC HIGH PRESSURE AXIS EXTENDED FROM SASKATCHEWAN THROUGH EASTERN
MONTANA AND THE WESTERN DAKOTAS TO CENTRAL NEBRASKA. THIS HIGH IS
FORECAST TO MOVE SOUTHEAST TO MISSOURI BY MONDAY MORNING.
WEST/NORTHWEST WINDS OVER CENTRAL AND EASTERN NORTH DAKOTA WILL
CONTINUE TO SUBSIDE AND BECOME LIGHT AFTER 00Z. CLEAR SKIES OVER THE
REGION...WITH SOME LOW LEVEL ICE CRYSTALS CAUSING KDIK AND KJMS TO
REPORT SCT-BKN CLOUD LAYERS AROUND 1000FT. NO VISIBLE CLOUDS WERE
APPARENT FROM SATELLITE PICTURES.

A STORM SYSTEM ON THE WEST COAST AND MOVING ACROSS THE ROCKIES WILL
BEGIN TO AFFECT NORTH DAKOTA AFTER DAYBREAK IN THE SOUTHWEST.
SOUTHEAST SURFACE WINDS AND INCREASING VFR CLOUDS MOVING IN FROM THE
SOUTHWEST...BECOMING MVFR WITH SNOW MONDAY AFTERNOON SPREADING
QUICKLY ACROSS THE STATE.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY UNTIL 9 PM CST /8 PM MST/ THIS EVENING FOR
NDZ002>005-010>013-018>023-025-033>037-041-042-044>048-050-051.

&&

SCHECK/JV

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE BISMARCK ND
433 AM CST SUN DEC 21 2008

NDZ001>005-009>013-017>023-025-031>037-040>048-050-051-221045-
DIVIDE-BURKE-RENVILLE-BOTTINEAU-ROLETTE-WILLIAMS-MOUNTRAIL-WARD-
MCHENRY-PIERCE-MCKENZIE-DUNN-MERCER-OLIVER-MCLEAN-SHERIDAN-WELLS-
FOSTER-GOLDEN VALLEY-BILLINGS-STARK-MORTON-BURLEIGH-KIDDER-
STUTSMAN-SLOPE-HETTINGER-GRANT-BOWMAN-ADAMS-SIOUX-EMMONS-LOGAN-
LA MOURE-MCINTOSH-DICKEY-
433 AM CST SUN DEC 21 2008 /333 AM MST SUN DEC 21 2008/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL
NORTH DAKOTA...NORTHWEST NORTH DAKOTA...SOUTH CENTRAL NORTH
DAKOTA...SOUTHEAST NORTH DAKOTA AND SOUTHWEST NORTH DAKOTA.

.DAY ONE...TODAY AND TONIGHT

DANGEROUS WIND CHILL TEMPERATURES AND AREAS OF BLOWING AND
DRIFTING SNOW THROUGH SUNDAY MORNING. A WIND CHILL WARNING REMAINS
IN EFFECT UNTIL UNTIL NOON CST OR 11 AM MST TODAY.

STRONG NORTHWEST WINDS OF 20 TO 35 MPH...WITH GUSTS UP TO AROUND
40 MPH...WILL CONTINUE ACROSS WEST AND CENTRAL NORTH DAKOTA THROUGH
SUNDAY MORNING. THESE WINDS COMBINED WITH ACTUAL AIR TEMPERATURES
BETWEEN 10 AND 20 BELOW ZERO...WILL PRODUCE DANGEROUS WIND CHILL
TEMPERATURES OF 40 TO 50 BELOW ZERO THROUGH EARLY SUNDAY AFTERNOON.
IN ADDITION...THE STRONG NORTHWEST WINDS COMBINED WITH RECENT
SNOWFALL WILL CONTINUE TO CREATE WIDESPREAD BLOWING AND DRIFTING
SNOW THROUGH SUNDAY MORNING...REDUCING VISIBILITIES TO BETWEEN ONE
AND THREE MILES...ESPECIALLY IN THE OPEN COUNTRY.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

MORE SNOW LATE MONDAY AND TUESDAY. ANOTHER STRONG NORTHEAST
PACIFIC STORM IS EXPECTED TO MOVE ONSHORE ACROSS THE PACIFIC
NORTHWEST LATER TODAY AND MOVE OUT ACROSS THE PLAINS MONDAY NIGHT
INTO TUESDAY. AS THIS OCCURS...SNOW IS LIKELY TO DEVELOP ACROSS
WESTERN AND SOUTHWESTERN NORTH DAKOTA MONDAY MORNING...BEFORE
SPREADING INTO CENTRAL NORTH DAKOTA BY LATE AFTERNOON AND EARLY
EVENING. SNOW WILL BECOME LIKELY MONDAY NIGHT AND GRADUALLY LESSEN
DURING THE DAY TUESDAY.

GIVEN THAT THIS STORM IS STILL A COUPLE OF DAYS AWAY...SOME
UNCERTAINTY EXISTS AS TO ITS EXACT EVOLUTION. HOWEVER...CURRENT
INDICATIONS CONTINUE TO SUGGEST THAT THIS STORM WILL BE CAPABLE OF
PRODUCING MODERATE SNOW ACCUMULATIONS ACROSS PORTIONS OF WESTERN
AND CENTRAL NORTH DAKOTA LATE MONDAY INTO TUESDAY. THEREFORE...THIS
STORM SYSTEM HAS THE POTENTIAL TO SIGNIFICANTLY IMPACT TRAVEL
ACROSS THE NORTHERN PLAINS EARLY THIS HOLIDAY WEEK. PERSONS
PLANING TRAVEL DURING THIS PERIOD ARE URGED TO CHECK THE LATEST
WEATHER FORECASTS AS WE GET CLOSER TO THIS EVENT.

THE REMAINDER OF THE HOLIDAY WEEK APPEARS TO BE QUIET...AT LEAST
THROUGH CHRISTMAS. TEMPERATURES WILL REMAIN WELL BELOW AVERAGE.
HOWEVER...TEMPERATURES ARE EXPECTED TO MODERATE SLIGHTLY ON
CHRISTMAS DAY WITH HIGHS BETWEEN 10 AND 25 ABOVE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED MONDAY NIGHT THROUGH TUESDAY FOR
SNOWFALL ACCUMULATION REPORTS.

KS/KJB/KS