Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 090532
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1132 PM CST MON FEB 8 2016

.UPDATE...
ISSUED AT 1132 PM CST MON FEB 8 2016

LATEST SURFACE ANALYSIS AND MODEL GUIDANCE SHOWS LOW LEVEL WARM
AIR ADVECTION FAR WESTERN NORTH DAKOTA WHERE 3HR PRESSURE FALLS
ARE MAXIMIZED. VERTICAL MOTION WITHIN THIS AREA HAS RESULTED IN
CEILINGS UNIFORMLY AROUND 5000FT. NO SIGNIFICANT FORCING MECHANISM
SEEN TO FURTHER ENHANCE VERTICAL MOTION AND GENERATE PRECIPITATION
THE REST OF THE NIGHT. THE BOWMAN AND BISMARCK RADAR SHOW A DISTINCT
LINE OF WEAKENING ECHOES IN FAR SOUTH CENTRAL AND SOUTHWEST NORTH
DAKOTA. PREVIOUS FORECAST HAD A DRY FORECAST OVERNIGHT AND WILL
MAINTAIN THIS THOUGHT.

LOOKING AHEAD...QUICK SCAN IN THE BUFKIT ANALYSIS AND 00Z NAM/GFS
MODEL SOLUTIONS...SHOW GOOD AGREEMENT IN GENERATING LIGHT SNOW
ACROSS THE WEST MID MORNING TUESDAY...THEN SPREADING INTO CENTRAL
NORTH DAKOTA BY AROUND 00Z WEDNESDAY. MOST PRECIPITATION EXPECTED
IN THE COLD SECTOR WITH A NARROW BAND OF LIGHT FREEZING RAIN IN
THE WARM SECTOR TUESDAY NIGHT. WILL AWAIT POPS IN THE NEXT CYCLE
TO EVALUATE THIS THREAT FOR TUESDAY NIGHT. OTHERWISE...THE CURRENT
FORECAST IS ON TRACK.

UPDATE ISSUED AT 920 PM CST MON FEB 8 2016

NO MAJOR CHANGES WERE NEEDED WITH THIS UPDATE. ADJUSTED
TEMPERATURES DOWN JUST A BIT IN THE NORTHEAST BASED ON THE LATEST
SHORT TERM GUIDANCE AND OBSERVATIONAL TRENDS. ALSO DECIDED TO HOLD
OFF ON PRECIPITATION CHANCES UNTIL 12Z TUESDAY DUE TO LATEST HIGH
RESOLUTION MODELS. IN THE WEST A FLURRY OR TWO IS POSSIBLE...BUT
BASED ON LATEST OBSERVATIONS AND A RELATIVELY DRY AIRMASS AT THE
SURFACE...DO NOT THINK THE CURRENT 0.5 DEGREE RADAR RETURNS FROM
KMBX ARE MAKING THEIR WAY TO THE GROUND. WILL BE WATCHING CLOSELY
AND ADJUSTING ACCORDINGLY SHOULD THIS BECOME LESS CERTAIN.

UPDATE ISSUED AT 542 PM CST MON FEB 8 2016

NO SIGNIFICANT CHANGES WITH THIS UPDATE. LATE AFTERNOON 0.5 DEGREE
RADAR REFLECTIVITY DATA SHOWS A NARROW LINE OF ECHOES MOVING EAST
AND EXTENDING FROM TIOGA SOUTH TO DICKINSON AND HETTINGER AT 2330
UTC. HOWEVER...WE BELIEVE THE ECHOES REPRESENT MID-LEVEL CLOUDS
AND NOT SURFACE PRECIPITATION GIVEN SUB-20 DBZ RETURNS BASED ABOVE
5000 FT AGL. IN FACT...POPS WERE REDUCED SLIGHTLY IN NORTHWEST ND
TO GO WITH A DRY FORECAST THROUGH 03 UTC GIVEN THE DRY BOUNDARY
LAYER WITH DEWPOINTS ONLY IN THE TEENS F OVER MUCH OF WESTERN ND
LATE THIS AFTERNOON. RECENT OPERATIONAL HRRR SIMULATIONS ARE MORE
ROBUST WITH LIGHT SNOW IN WESTERN ND LATE TONIGHT THAN THE ESRL-
RUN EXPERIMENTAL HRRR...WHICH ALSO REPRESENTS UNCERTAINTY THAT IS
LIKELY RELATED TO THE DRY LOWER ATMOSPHERE AND WEAK FORCING.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 229 PM CST MON FEB 8 2016

CURRENT SURFACE ANALYSIS PLACES LOW OVER THE GREAT LAKES WITH
RIDGE RUNNING THROUGH THE WESTERN PLAINS. UPPER LEVEL ANALYSIS
PLACES RIDGE OVER THE WESTERN CONUS WITH LOW NEAR LAKE MICHIGAN
WHILE FAST NORTH-NORTHWESTERLY FLOW REMAINS OVER OUR AREA.

FOR THE REST OF THIS AFTERNOON INTO TONIGHT...QUIET WEATHER WILL
START THE EVENING WITH BREEZY WINDS DIMINISHING AS PRESSURE
GRADIENT CONTINUES TO GRADUALLY RELAX OVER THE REGION. LATER THIS
EVENING WEAK WARM AIR ADVECTION ALOFT DEVELOPS RESULTING IN MODEST
ISENTROPIC LIFT DEVELOPING OVER WESTERN LOCATIONS...BRINGING A
LOW CHANCE FOR SNOW.

ON TUESDAY...STRONG TEMPERATURE GRADIENT WILL BE SET UP OVER THE
AREA WITH TEENS OVER THE EASTERN PART OF THE FORECAST AREA...AND
AROUND 40 OVER THE FAR SOUTHWEST. MODEST CHANCES FOR PRECIPITATION WILL
REMAIN IN BROAD BAROCLINIC ZONE SET UP OVER WESTERN INTO CENTRAL
PARTS OF NORTH DAKOTA. MOST AREAS MAY SEE SOME SNOW...BUT CHANCES
SWITCH TOWARDS RAIN OVER PORTIONS OF THE WEST AS WARMER AIR TRIES
TO WORK EASTERLY.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 229 PM CST MON FEB 8 2016

THE MAIN FOCUS FOR THE LONG TERM IS THE POTENTIAL FOR FREEZING
RAIN AND SNOW TUESDAY NIGHT INTO WEDNESDAY.

A VERY TIGHT BAROCLINIC ZONE WILL SET UP ACROSS THE STATE THROUGH
THE REST OF THE WEEK. NORTHWEST FLOW ALOFT WILL CARRY SEVERAL
UPPER LEVEL SHORT WAVE TROUGHS ACROSS THE NORTHERN PLAINS. AS
THESE WAVES APPROACH BRIEF PERIODS OF MID-LEVEL WARM AIR ADVECTION
WILL OCCUR ACROSS PORTIONS OF WESTERN AND CENTRAL NORTH DAKOTA.
AT THIS TIME IT APPEARS THE FIRST SUCH WAVE WILL APPROACH THE
REGION TUESDAY NIGHT INTO WEDNESDAY. FORECAST SOUNDINGS CLEARLY
SHOW A WARM LAYER ALOFT...WITH SURFACE TEMPERATURES BELOW
FREEZING. THERE ARE SOME DISCREPANCIES BETWEEN MODELS AS TO JUST
HOW WARM THIS LAYER IS AND HOW FAR EAST IT WILL PUSH.
HOWEVER...THERE IS AT LEAST THE POSSIBILITY OF FREEZING RAIN
TUESDAY NIGHT INTO WEDNESDAY AS BELOW FREEZING SURFACE
TEMPERATURES SHOULD COINCIDE WITH THE BEST FORCING AND WARM LAYER
ALOFT. AS PRECIPITATION PUSHES FURTHER EAST IT WILL ENCOUNTER
COOLER AIR BOTH ALOFT AND AT THE SURFACE AND SHOULD TRANSITION OR
REMAIN ALL SNOW. EXACTLY WHERE THIS TRANSITION ZONE WILL SET UP
IS VERY UNCERTAIN AT THIS TIME AS THE TEMPERATURE GRADIENT WILL
LIKELY BE VERY STEEP AND A SLIGHT SHIFT IN THE BAROCLINIC ZONE
COULD MEAN VERY DIFFERENT PRECIPITATION TYPES.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1132 PM CST MON FEB 8 2016

CIGS AROUND 5KFT TO BEGIN THIS TAF PERIOD...THEN TRENDING TO MVFR
IN THE WESTERN/NORTHERN TERMINALS OF KISN/KDIK/KMOT 15Z-17Z
TUESDAY. LIGHT SNOW WILL DEVELOP AT KISN/KDIK DURING THE SAME TIME
PERIOD ABOVE RESULTING IN MVFR-IFR VSBYS. CIGS WILL LOWER TO MVFR
AT KBIS BY 19Z WITH LIGHT SNOW FORECAST INTO KMOT/KBIS AROUND 00Z
WEDNESDAY. VSBYS WILL ALSO LOWER TO IFR/MVFR IN LIGHT SNOW. KJMS
WILL REMAIN VFR THROUGH 06Z WEDNESDAY.

&&

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

$$

UPDATE...KS
SHORT TERM...JJS
LONG TERM...AJ
AVIATION...KS


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