000
FXUS63 KBIS 010346
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
946 PM CST SAT NOV 30 2013

.UPDATE...
ISSUED AT 933 PM CST SAT NOV 30 2013

SHALLOW COOL AIR OOZING SOUTHWEST TO A WESTHOPE TO JAMESTOWN LINE
AND LOW CLOUDS AND FOG ARE FORMING ALONG THE LEADING EDGE OF
THE COOL AIR. VISIBILITIES IN THE FOG GENERALLY BETWEEN ONE HALF
AND 1 MILE...WITH A FEW SPOTS AROUND ONE QUARTER MILE. AS MID
CLOUDS FROM THE WEST OVER RUN THE LOWER CLOUDS AND FOG TO THE EAST
EXPECT SOME IMPROVEMENT IN VISIBILITIES...AND THE WARM AIR
ADVECTION ASSOCIATED WITH MID CLOUDS SHOULD SLOW/STOP THE ADVANCING
COOL AIR LIMITING THE TRAVEL NO FURTHER WEST THAN A MINOT TO
BISMARCK LINE. WILL HANDLE THE FOG WITH A SPECIAL WEATHER
STATEMENT. TO THE WEST...SOME LIGHT PRECIPITATION MOVING INTO
NORTHEAST MONTANA. BUFKIT SOUNDINGS SHOW FREEZING RAIN THE LIKELY
PRECIP TYPE DO TO SHALLOWNESS OF COOL AIR AT WILLISTON. HOWEVER
CANT RULE OUT SLEET EITHER. SO KEPT A WINTRY MIX AT 40 PERCENT
POPS ACROSS THE NORTHWEST AFTER MIDNIGHT.

UPDATE ISSUED AT 620 PM CST SAT NOV 30 2013

SHALLOW COOL AIR ACROSS SOUTHERN CANADA AND NORTH CENTRAL NORTH
DAKOTA BRINGING IN SOME LOW LEVEL CLOUDS AND FOG ACROSS THE TURTLE
MOUNTAINS. SOME FOG SHOWING UP AT MINOT AIR FORCE BASE AND WILL MOVE
INTO MINOT SHORTLY. ADDED PATCHY FOG ACROSS THE NORTHERN COUNTIES
FOR THE EVENING. A LARGE AREA OF CLEAR SKIES REMAIN OVER
NORTHWEST AND CENTRAL NORTH DAKOTA. THIS AREA WILL FILL IN WITH
CLOUDS LATER TONIGHT BUT FOR THE EVENING SKIES WILL BE CLEAR.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 252 PM CST SAT NOV 30 2013

THE MAIN FORECAST CONCERNS IN THE SHORT TERM WILL BE PRECIPITATION
CHANCES LATE TONIGHT INTO SUNDAY. THERE IS GENERAL AGREEMENT AMONG
THE SHORT TERM MODELS THAT ANOTHER UPPER WAVE WILL MOVE ACROSS THE
NORTHERN PLAINS TONIGHT INTO SUNDAY AS AN H3 JET APPROACHES THE
REGION. THERE ARE SOME DIFFERENCES IN TIMING...BUT MOST SOLUTIONS
KEEP THE PRECIPITATION CHANCES WEST OF THE FORECAST AREA UNTIL LATE
TONIGHT. WILL SHOW INCREASING POPS IN THE WEST AFTER
MIDNIGHT...AND THEN SPREAD THE HIGHER POPS ACROSS WESTERN AND
CENTRAL NORTH DAKOTA ON SUNDAY.

PRECIPITATION TYPE WILL BE A CHALLENGE WITH THERMAL PROFILES
SUGGESTING MAINLY SNOW IN THE NORTH AND EAST...HOWEVER WARMER AIR
IS EXPECTED TO BE IN PLACE IN THE SOUTH AND WEST. HAVE GONE WITH A
MIX OF PRECIPITATION TYPES IN THE WEST CENTRAL AND SOUTHWEST LATE
TONIGHT AND SUNDAY. KEPT MOST SNOW AMOUNTS AN INCH OR LESS...AND
DID NOT CARRY ANY ICE ACCUMULATIONS DUE TO THE UNCERTAINTY STILL
SURROUNDING THE THERMAL PROFILES. LATER SHIFTS WILL HAVE TO KEEP
AN EYE ON HOW THINGS PROGRESS...BUT DO NOT HAVE ENOUGH CONFIDENCE
IN THE MIXED PRECIPITATION ACCUMULATING ENOUGH TONIGHT / SUNDAY TO
WARRANT THE ISSUANCE OF ANY ADVISORIES AT THE MOMENT.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 252 PM CST SAT NOV 30 2013

THE HIGHLIGHT OF THE EXTENDED FORECAST IS A POTENTIAL PROLONGED
SNOW EVENT MONDAY THROUGH WEDNESDAY...FOLLOWED BY VERY COLD ARCTIC
AIR.

THE 12 UTC DETERMINISTIC GUIDANCE IS IN GOOD AGREEMENT ON
SURFACE CYCLOGENESIS ACROSS SOUTHEAST ALBERTA AND INTO CENTRAL
MONTANA SUNDAY NIGHT INTO MONDAY. IN RESPONSE...A BAND OF
PRECIPITATION IN LOW LEVEL ISENTROPIC LIFT IS FORECAST TO DEVELOP
ACROSS NORTHWEST AND INTO CENTRAL NORTH DAKOTA. PRECIPITATION IS
EXPECTED TO BE ALL SNOW ACROSS NORTHERN NORTH DAKOTA AND INTO THE
JAMES RIVER VALLEY. HOWEVER...A MIX OF FREEZING RAIN AND SLEET IS
POSSIBLE ON THE WESTERN PERIPHERY OF THE BAND...ESPECIALLY DURING
THE MORNING...WHERE A +1 TO +3 C MELTING LAYER ALOFT WILL BE IN
PLACE. A WINTER WEATHER ADVISORY MAY BE NEEDED FOR THIS EVENT AS
TWO TO FOUR INCHES OF SNOW ARE POSSIBLE ALONG AND NORTH OF US
HIGHWAY 2 AND INTO THE JAMES RIVER VALLEY...WITH POSSIBLE MINOR
ICE ACCUMULATIONS ACROSS THE SOUTH CENTRAL.

FOR THE MONDAY NIGHT THROUGH WEDNESDAY PORTION OF THE STORM...THE
12 UTC GFS/NAM AND 15 UTC SREF WERE DISCOUNTED AS THEY EJECT A
DEEP AND RAPIDLY PROPAGATING UPPER LEVEL LOW OUT OF THE MAIN
LONGWAVE. THIS IS MUCH DIFFERENT AND A SIGNIFICANT CHANGE FROM THE
PREFERRED 12 UTC ECMWF AND GEM SOLUTIONS. FOLLOWING THESE
SOLUTIONS...A PROLONGED PERIOD OF LIGHT TO MODERATE SNOW IS
EXPECTED FROM MONDAY NIGHT THROUGH WEDNESDAY ACROSS OF WESTERN AND
CENTRAL NORTH DAKOTA WITH A DEEP FETCH OF SOUTHWEST FLOW ALOFT.
HEAVY SNOWFALL ACCUMULATIONS ARE POSSIBLE...WITH BLOWING SNOW
BECOMING A THREAT WEDNESDAY ON THE BACKSIDE OF THE SURFACE LOW.
THEREAFTER...VERY COLD ARCTIC AIR TAKES OVER THE REGION INTO THE
WEEKEND.



&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 933 PM CST SAT NOV 30 2013

MAIN HAZARDS TO AVIATION THIS TAF PERIOD INCLUDE VERY LOW IFR
CONDITIONS FROM KMOT-KJMS IN LOW CEILINGS AND FREEZING FOG.
ANOTHER CONCERN WILL BE A MIX OF FREEZING RAIN AND SLEET ACROSS
KISN AS A LOW PRESSURE AREA SPREADS SOME LIGHT PRECIPITATION INTO
NORTHWEST NORTH DAKOTA BETWEEN 06Z-12Z. AFTER 12Z LOOKING FOR A
BAND OF SNOW FROM BETWEEN KISN-KMOT SOUTH TO KBIS WITH MVFR
CEILINGS AND VSBYS IN SNOW.

&&

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

$$

UPDATE...WAA
SHORT TERM...CK
LONG TERM...AYD
AVIATION...WAA