Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 210626
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1226 AM CST SUN DEC 21 2014

.UPDATE...
ISSUED AT 1226 AM CST SUN DEC 21 2014

MAIN CONCERN THIS UPDATE IS THE PRECIPITATION NORTH CENTRAL...FROM
BOTTINEAU AND THE TURTLE MOUNTAINS TO RUGBY. FORECAST SOUNDINGS
INDICATE THE PRECIPITATION SHOULD BE IN THE FORM OF FREEZING
RAIN...BUT MAY BE MIXING WITH OR CHANGING TO SNOW. THE AREA OF
PRECIPITATION WAS MOVING EAST AND SHOULD BE OUT OF THIS AREA BY
AROUND 2 AM CST.

THE LOW CLOUDS PERSISTED EAST OF MINOT AND JAMESTOWN AT
MIDNIGHT...BUT HRRR MODEL INDICATES LOW CLOUDS AND FOG RETURNING.
LESS CERTAIN FOR AS FAR SOUTHWEST AS BISMARCK.

UPDATE ISSUED AT 907 PM CST SAT DEC 20 2014

MAIN ISSUE THIS EVENING IS THE FREEZING RAIN AT NORTH CENTRAL. AS
THE PRECIP MOVES EAST INTO COLDER AIR IT IS EXPECTED TO CHANGE
OVER TO SNOW BASED ON MAT TEMP ALOFT FORECAST. WILL RAISE THE
CHANCE TO LIKELY CATEGORY OVER THE NORTH CENTRAL THIS EVENING. SO
FAR WILL HANDLE THIS LIGHT PRECIPITATION WITH SPECIAL WEATHER
STATEMENTS AND SOCIAL MEDIA POSTS.

UPDATE ISSUED AT 644 PM CST SAT DEC 20 2014

SEEING SOME VISIBILITY REDUCTION DUE TO SNOW/MIXED PRECIPITATION AT
TIOGA AND STANLEY WITH A NARROW BAND OF PRECIPITATION. REFINED THIS
AREA IN THE FORECAST ACROSS THE NORTH CENTRAL..AND RAISED POPS T
40 AS IT MOVES TOWARD MINOT. AM CONCERNED ABOUT THE STRATUS ACROSS
THE NORTH CENTRAL AND EAST CENTRAL. HRRR CONTINUES TO SHOW THE
STRATUS FILLING BACK IN ALTHOUGH THE SATELLITE TRENDS SHOW
CONTINUES MOVEMENT EAST OUT OF JAMESTOWN. WILL WATCH FOR THIS
TREND TO CHANGE.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)

ISSUED AT 336 PM CST SAT DEC 20 2014

FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE LINGERING
PRECIPITATION ASSOCIATED WITH A MID LEVEL WAVE MOVING EAST ACROSS
THE NORTHERN PLAINS TONIGHT...FOG REDEVELOPMENT TONIGHT EASTERN
HALF ALONG TO EAST OF HIGHWAY 83...THEN THE ONSET OF
PRECIPITATION WITH A STRONG STORM SYSTEM ON SUNDAY.

CURRENTLY...MID LEVEL S/WV IMPULSE OVER NORTHWESTERN NORTH DAKOTA
WITH AN ASSOCIATED SFC TROUGH/WARM FRONTAL BOUNDARY DRAPED NORTH
TO SOUTH-SOUTHEAST ACROSS THE CENTRAL DAKOTAS. BAND OF MID LEVEL
CLOUDS AND WEAK RADAR RETURNS ALONG THE BOUNDARY OVER MY EASTERN
COUNTIES AT THE MOMENT...WITH CLEARING SKIES WEST. THE EXCEPTION
IS OVER THE FAR NORTHWEST WHERE WRAP AROUND MOISTURE IS MOVING
INTO...WHERE WE EXPECT INCREASING CLOUDS AND A CHANCE FOR LIGHT
PRECIPITATION EITHER IN THE FORM OF RAIN OR A WINTRY MIX MID TO
LATE AFTERNOON.

WHILE THE BAND OF MID LEVEL CLOUDS IS EATING AWAY AT THE STRATUS
AND FOG CENTRAL INTO EAST...HIGH RES MODELS STRONGLY SUGGEST
REDEVELOPMENT INITIALLY WHERE IT IS AT NOW OVER MY EASTERN
COUNTIES...THEN EXPANDING WEST TO THE HIGHWAY 83 CORRIDOR. WRAP
AROUND PRECIPITATION WILL ALSO WORK ITS WAY EAST TONIGHT ACROSS
THE NORTH BEHIND THE AFOREMENTIONED MID LEVEL WAVE.

NEXT STORM SYSTEM ARRIVES SUNDAY. LEFT EXIT REGION OF A STRONG
UPPER LEVEL JET STREAK WILL PROMOTE LOW PRESSURE DEVELOPMENT OVER
NORTH CENTRAL MONTANA LATE TONIGHT INTO SUNDAY MORNING...WITH
THIS FEATURE THEN MOVING SOUTHEAST INTO EASTERN MONTANA DURING
SUNDAY AFTERNOON. FORCING WILL BE PLENTIFUL WITH INCREASING UPPER
LEVEL DIVERGENCE ON THE NOSE OF THE UPPER JET AND LOW LEVEL
THERMAL UPGLIDE AHEAD OF THE SFC LOW/WARM FRONT. ALREADY PLENTY
OF MOISTURE SO INCREASED POPS TO LIKELY/DEF WEST. THIS EVENT
CONTINUES INTO THE LONG TERM PERIOD SUNDAY NIGHT. SEE BELOW FOR
FURTHER DETAILS.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 336 PM CST SAT DEC 20 2014

RAIN...FREEZING RAIN AND SNOW ARE LIKELY ACROSS THE REGION SUNDAY
INTO MONDAY.

FOR THE SUNDAY INTO MONDAY FORECAST WENT WITH A BLEND OF THE 12
UTC ECMWF/GFS/SREF AS THEY HAVE COME INTO BETTER AGREEMENT AND
DEPICT A REASONABLE SCENARIO. THE 12 UTC NAM APPEARED TO BE TOO
SLOW...TOO MOIST AND BROUGHT THE SURFACE LOW FURTHER NORTHEAST THAN THE
REST OF THE GUIDANCE. HOWEVER...IT IS IMPORTANT TO NOTE THAT THE
18 UTC NAM THAT JUST CAME IN HAS COME INTO BETTER AGREEMENT WITH
THE OTHER GUIDANCE AND NOW HAS THE LOW MOVING A BIT QUICKER AND
TRACKING ACROSS SOUTHWEST NORTH DAKOTA.

...THE MAIN FORECAST CHALLENGE AND UNCERTAINTIES WITH THIS SYSTEM ARE
PRECIP TRANSITION TIMES AND AMOUNTS...

RECENT MODEL TRENDS INDICATE WARMER AIR ALOFT WILL NOT BE AS
PRONOUNCED AND THEREFORE PRECIP TYPES SHOULD BE DETERMINED BY
SURFACE TEMPERATURE ALONE AND LIMITED TO RAIN/FREEZING RAIN/SNOW.
INITIALLY DRY AIR IS EXPECTED TO OCCUPY THE 850-700 MB LAYER. THIS
SHOULD LIMIT INITIAL PRECIP TO A LIGHT DRIZZLE...REGARDLESS OF SURFACE
TEMPERATURES...DUE TO LACK OF ICE (NO SNOW ALOFT). AS MOISTURE
FROM THE WEST MOVES IN AND COLD AIR ADVECTION ALOFT TAKES
HOLD...THE COLUMN SHOULD EVENTUALLY SATURATE AND SNOW WOULD LIKELY
FOLLOW. TEMPERATURES SUNDAY AFTERNOON/EVENING SHOULD BE WARM
ENOUGH ACROSS THE SOUTHWEST TO KEEP ALL PRECIPITATION LIQUID
THROUGH THE EARLY EVENING HOURS. THE INITIAL WAVE OF MOISTURE IS
EXPECTED TO ENTER WESTERN NORTH DAKOTA SHORTLY AFTER SUNSET. COLD
AIR SHOULD TAKE HOLD AFTER MIDNIGHT. IT IS AT THIS TIME WHEN A
TRANSITION TO SNOW IS EXPECTED. LIGHT SNOW IS THEN EXPECTED TO
FALL THROUGH THE DAY MONDAY...EVENTUALLY ACCUMULATING AROUND 3
INCHES ACROSS WESTERN NORTH DAKOTA AND THE JAMES RIVER VALLEY.
CENTRAL NORTH DAKOTA MAY EXPERIENCE A LOCAL MINIMUM OF SNOWFALL AS
THE LOW IS PROGGED TO PIVOT ALONG THE RED RIVER (KEEPING MOST OF
THE MOISTURE ALONG AND EAST OF THE JAMES VALLEY THROUGH THE DAY).
IN ADDITION TO SNOW...GUSTY WINDS AROUND 35 MPH MAY CREATE SOME
BLOWING SNOW...REDUCING VISIBILITY. THE STRONGEST WINDS ARE
EXPECTED ACROSS SOUTHWEST AND SOUTH CENTRAL NORTH
DAKOTA...COINCIDENT WITH A 10 MB/6 HOUR PRESSURE RISE.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1226 AM CST SUN DEC 21 2014

AT MIDNIGHT CST...A WARM FRONT EXTENDED FROM LOW PRESSURE IN
ALBERTA/SASKATCHEWAN SOUTHEAST THROUGH EASTERN NORTH DAKOTA. THE
FRONT WILL BE THE FOCUS FOR A WINTRY MIX OF FREEZING RAIN AND SNOW
FROM BOTTINEAU AND THE TURTLE MOUNTAINS TO THE RUGBY AND HARVEY
AREAS THROUGH 2 AM CST. OTHERWISE AREAS OF FOG WILL AGAIN PLAGUE THE
REGION FROM A MINOT TO BISMARCK LINE. IFR CONDITIONS ARE EXPECTED TO
REDEVELOP EAST OF THIS LINE AND REMAIN VFR WEST. ANOTHER LOW
PRESSURE SYSTEM WILL APPROACH WESTERN NORTH DAKOTA SUNDAY AFTERNOON.
THIS COULD BRING A THREAT FOR FREEZING RAIN/SLEET/SNOW AT KISN AFTER
NOON CST. LEFT VCSH FOR NOW DUE TO UNCERTAINTY...BUT ADDED MENTION
OF -SN AFT 03Z. MORE CERTAIN ABOUT LIGHT RAIN MOVING INTO THE KDIK
AREA AFT 20Z.

&&

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

$$

UPDATE...JV
SHORT TERM...NH
LONG TERM...AJ
AVIATION...JV





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