Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 130041
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
641 PM CST FRI FEB 12 2016

.UPDATE...
ISSUED AT 633 PM CST FRI FEB 12 2016

NO SIGFINIFCANT CHANGES FOR THE EVENING UPDATE. WITH COLD SURFACE
HIGH SITTING OVER EASTERN NORTH DAKOTA AND PARTLY CLOUDY
SKIES...DID LOWER TEMPERATURES A BIT IN THE FAR EAST. HOWEVER WITH
WARM ADVECTION AND INCREASING CLOUDS FROM THE WEST. THINK LOWS
WILL OCCUR SOMETIME AROUND MIDNIGHT AND THEN START TO RISE TOWARD
MORNING. CURRENT TIMING FOR LIGHT SNOW THIS EVENING WEST LOOKS
GOOD IN THE WEST WITH RETURNS INCREASING ACROSS EASTERN MONTANA.

&&

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

ISSUED AT 415 PM CST FRI FEB 12 2016

THE FOCUS OF THE SHORT TERM FORECAST IS THE POTENTIAL FOR A WINTRY
MIX IN WESTERN ND AND SNOWFALL IN CENTRAL ND ON SATURDAY.

THE 12 UTC GFS...ECMWF...AND NAM AND MORE RECENT RAP/HRRR RUNS ALL
SUGGEST A BAND OF LIGHT SNOW WILL MOVE ACROSS WESTERN ND TONIGHT
AND INTO CENTRAL ND BY EARLY SATURDAY MORNING. THOSE SIMULATIONS
ALL SUGGEST LIQUID-EQUIVALENT MOISTURE TOTALS WILL BE SMALL AND
THAT TEMPERATURES ALOFT WITH THIS WEAK...WARM-ADVECTION-INDUCED
BATCH OF LIGHT PRECIPITATION WILL BE COLD ENOUGH FOR ALL SNOW.
GUIDANCE EXPECTS THIS SNOWFALL TO WEAKEN AS IT REACHES CENTRAL
NORTH DAKOTA BY SATURDAY...WHERE FORECAST SOUNDINGS SUGGEST THE
LOWER TO MIDDLE ATMOSPHERE WILL BE RELATIVELY DRY INITIALLY.

ON SATURDAY...MAXIMUM TEMPERATURES ALOFT WILL RISE INTO THE +3 TO
+6 C RANGE IN WEST CENTRAL AND SOUTHWEST ND AS WARM AIR ADVECTION
CONTINUES. APPLYING THE TOP-DOWN METHOD TO MODEL-FORECAST THERMAL
PROFILES SUPPORTS A MIX OF LIGHT FREEZING RAIN...SLEET...OR SNOW
IN WEST CENTRAL AND SOUTHWEST ND...ESPECIALLY ALONG THE CORRIDOR
OF HIGHWAYS 85 AND 22 DURING THE AFTERNOON. HOWEVER...TAKING THE
12 UTC GLOBAL MODEL SUITE AT FACE VALUE SUGGESTS THERE MAY BE A
RELATIVE LULL IN VERTICAL MOTION DURING THE TIME DURING WHICH THE
THERMAL PROFILES SUPPORT MELTING OF HYDROMETEORS ALOFT...AND THUS
THE LIKELIHOOD OF PRECIPITATION ACTUALLY OCCURRING WHEN AN IMPACT-
WORTHY TYPE OCCUR IS IN QUESTION. MOREOVER...AN IN-HOUSE MODEL OF
ROAD TEMPERATURES SUGGESTS THEY MAY RISE WELL ABOVE 32 F SATURDAY
AFTERNOON TOO...AND FAR SOUTHWESTERN ND WILL LIKELY WARM UP ENOUGH
FOR EITHER RAIN OR SNOW INSTEAD OF FREEZING RAIN OR SLEET. WE THUS
DID NOT HAVE ENOUGH CONFIDENCE TO HOIST ANY HEADLINES FOR FREEZING
RAIN AT THIS POINT...ESPECIALLY GIVEN UNCERTAINTY IN WHETHER THERE
WILL ACTUALLY BE ANY PRECIPITATION FALLING BEFORE THE TEMPERATURES
ALOFT BEGIN COOLING AGAIN BY LATE SATURDAY AFTERNOON.

HEIGHT FALLS ALOFT WILL LIKELY INDUCE INCREASING PRECIPITATION IN
THE AREA BY LATE SATURDAY AFTERNOON...BUT THE 12 UTC CONVECTION-
ALLOWING...NCEP-RUN WRF-ARW AND WRF-NMM ARE LIKELY TOO AGGRESSIVE
WITH THEIR SIMULATION OF THAT PRECIPITATION DURING THE AFTERNOON.
THE MODEL RESULTS ARE LIKELY A RESULT OF SEASONABLY STEEP LAPSE
RATES ALOFT...BUT FORCING AND UPRIGHT INSTABILITY FIELDS ARE NOT
PARTICULARLY FAVORABLE FOR DEEP CONVECTION LIKE THAT GUIDANCE
SUGGESTS. REGARDLESS...WE HAVE 40-60 PERCENT POPS IN PLACE FOR
MOST AREAS SATURDAY AFTERNOON.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)

ISSUED AT 415 PM CST FRI FEB 12 2016

ONGOING ACTIVE WEATHER OR PERHAPS THE BEGINNING OF ACTIVE WEATHER
AT THE ONSET OF THE LONG TERM PERIOD SATURDAY NIGHT. WE REMAIN
ACTIVE THROUGH EARLY NEXT WEEK...FOLLOWED BY A QUIETER AND WARMER
PERIOD MID TO LATE NEXT WEEK.

CONTINUING FROM THE SHORT TERM DISCUSSION...COOLING ALOFT WITH
MID LEVEL CAA AND EVAPORATIVE COOLING SHOULD RESULT IN PRIMARILY
SNOW SATURDAY EVENING...SO HAVE NO MENTION OF FREEZING
PRECIPITATION 00Z AND ONWARD. STILL UNCERTAINTY ON PLACEMENT AND
AMOUNTS OF SNOW...BUT WHEN LEANING TOWARDS THE 12/18Z GFS AND 12Z
ECMWF...RESULTS IN THE MORE FAVORABLE PRECIPITATION AREAS OVER
CENTRAL AND EASTERN PORTIONS OF THE FORECAST AREA ALONG TO EAST OF
A SLOWLY EASTWARD ADVANCING SFC TROUGH/DOUBLE BARRELED LOW
PRESSURE SYSTEM AHEAD OF THE MAIN MID LEVEL S/WV. BOTH THE GFS/EC
FAVOR THE HEAVIER QPF TO OUR SOUTH ACROSS SOUTH DAKOTA NEAR THE
BASE OF THE MID LEVEL S/WV TROUGH AND WHERE MODELS SUGGEST THE
SOUTHERN LOW LEVEL CIRCULATION TO TRACK. STILL POSSIBLE TO SEE
ADVISORY CRITERIA SNOW ACROSS THE JAMES RIVER VALLEY...BUT IT
APPEARS MODELS ARE TRENDING IN THE ABOVE MENTIONED DIRECTION.
DISCARDED THE NAM OUTPUT FOR THIS FORECAST ISSUANCE FOR THIS
PERIOD AS IT IS AN OUTLIER.

SNOW ENDS SUNDAY MORNING WITH RELATIVELY MILD TEMPERATURES
FILTERING WEST INTO THE STATE FOR SUNDAY AFTERNOON.

ANOTHER CHANCE AT WINTER WEATHER RETURNS WITH POSSIBLE IMPACTS
LATER MONDAY INTO MONDAY NIGHT WHEN MODELS ADVERTISE ANOTHER S/WV
MOVING THROUGH THE REGION. NEEDLESS TO SAY HIGH UNCERTAINTY AT
THIS TIME FOR THIS FEATURE.

BROAD UPPER LEVEL RIDGING SHOULD DRY THINGS OUT TOWARDS THE MIDDLE
OF THE WORK WEEK ALONG WITH MILD/ABOVE NORMAL TEMPERATURES IN THE
30S AND 40S. WOULD NOT RULE OUT A FEW LOWER 50S WHERE THERE IS NO
SNOW COVER.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 633 PM CST FRI FEB 12 2016

VFR CONDITIONS TO START THE 00Z TAF PERIOD. A BAND OF LIGHT SNOW
WILL MOVE INTO WESTERN NORTH DAKOTA THIS EVENING WITH CEILINGS
LOWERING TO MVFR 03-06 UTC...AND MOVE INTO THE CENTRAL PART OF
THE STATE EARLY SATURDAY...WITH MVFR CEILINGS BY AROUND 12 UTC.
EXPECT MVFR CEILINGS TO REMAIN THROUGH THE DAY AT CENTRAL ND SITES
WITH PERHAPS A PERIOD OF LOW VFR CEILINGS AT KISN AND KDIK 12-18Z
BEFORE LOWERING BACK TO MVFR AFT 18Z SAT.

&&

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

$$

UPDATE...TWH
SHORT TERM...CJS
LONG TERM...NH
AVIATION...TWH


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