Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 230654
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1254 AM CST SUN NOV 23 2014

.UPDATE...
ISSUED AT 1254 AM CST SUN NOV 23 2014

HOURLY TEMPERATURE FORECAST HAS BEEN THE MAIN ISSUE WITH THIS
UPDATE.

VIGOROUS SURFACE LOW PRESSURE SYSTEM WAS CENTERED OVER SOUTHEASTERN
SASKATCHEWAN NEAR REGINA. THE COLD FRONT EXTENDED
WESTWARD/SOUTHWESTWARD AND REMAINED JUST NORTH OF THE MONTANA
BORDER. AS THE COLD FRONT APPROACHES...WEST WINDS INCREASE TO 15 TO
25 MPH WITH GUSTS OVER 30 MPH AND TEMPERATURES HAVE RISEN. WINDS IN
WESTERN NORTH DAKOTA WERE WESTERLY AND TEMPERATURES HAVE RISEN INTO
THE UPPER 30S TO AROUND 40 DEGREES F. MEANWHILE LIGHTER
SOUTHERLY/SOUTHWESTERLY WINDS WERE IN CENTRAL NORTH DAKOTA...WHERE
TEMPERATURES HAVE DROPPED INTO THE UPPER 20S/LOWER 30S. ATTEMPTING
TO FORECAST THE HOUR BY HOUR TEMPERATURES IN THIS SCENARIO HAS BEEN
CHALLENGING. TO MAKE THINGS MORE COMPLICATED...AN AREA OF RADAR
RETURNS WITH PRESUMED LIGHT PRECIPITATION OR VIRGA CONTINUES ACROSS
SOUTH DAKOTA...WITH THE NORTHERN EDGE ACROSS SOUTHERN PARTS OF
SOUTHWESTERN AND SOUTH CENTRAL NORTH DAKOTA. AS THIS AREA
APPROACHES...TEMPERATURES HAD RISEN AS WELL. LIKELY RAIN OVER THE
BULK OF THE RADAR RETURN AREA...HOWEVER THE LEADING EDGE OF THE AREA
MAY BE BRIEF FREEZING RAIN AS THE PRECIPITATION APPROACHES ALREADY
SUB-FREEZING SURFACE AIR.

OTHERWISE NO BIG CHANGES THIS UPDATE...AND AWAIT THE COLD FRONT AND
STRENGTHENING WINDS ASSOCIATED WITH THIS STRONG SYSTEM.

UPDATE ISSUED AT 956 PM CST SAT NOV 22 2014

LIGHT RAIN HAS MOVED INTO SOUTHWEST NORTH DAKOTA...WHILE THE RAIN
IN THE CENTRAL PART OF THE STATE HAS MOVED EAST AND OUT OF THE
FORECAST AREA. PRECIPITATION TYPE REMAINS A CONCERN WITH SURFACE
TEMPERATURES AT OR JUST BELOW FREEZING IN PARTS OF THE SOUTH
CENTRAL AND TOWARDS THE JAMES RIVER VALLEY. THIS COULD BRING A
BRIEF PERIOD OF LIGHT FREEZING RAIN TO SOME LOCATIONS...BUT
COMPLICATING THE MATTER IS THAT TEMPERATURES HAVE TENDED TO RISE A
FEW DEGREES IN ADVANCE OF THE PRECIPITATION. A BRIEF PERIOD OF
SLEET ALSO APPEARS POSSIBLE AS COLDER AIR ARRIVES BEHIND A COLD
FRONT LATER TONIGHT. ALL THE PRECIPITATION SHOULD CHANGE TO SNOW FROM
WEST TO EAST ONCE THE COLDER AIR MOVES INTO THE AREA. OVERALL...IT
APPEARS PRECIPITATION AMOUNTS SHOULD REMAIN FAIRLY LIGHT TONIGHT
WITH MODEL QPF REMAINING LOW FROM THE 00Z RUNS OF THE NAM AND GFS.
DID NOT MAKE ANY LARGE SCALE CHANGES WITH MOST ADJUSTMENTS TO
CAPTURE THE LATEST TRENDS.

UPDATE ISSUED AT 607 PM CST SAT NOV 22 2014

AN AREA OF LIGHT RAIN CONTINUES TO MOVE ACROSS CENTRAL NORTH
DAKOTA AT THIS HOUR...WITH OTHER LIGHT ECHOES SHOWN BY AREA RADARS
IN EASTERN MONTANA. SHORT TERM MODELS SOLUTIONS INCLUDING THE
HRRR...SUPPORT A GENERAL DECLINE IN THE PRECIPITATION THIS
EVENING IN CENTRAL NORTH DAKOTA...WHILE THE PRECIPITATION IN
EASTERN MONTANA EVENTUALLY ARRIVES IN THE WESTERN PART OF THE
STATE. HAVE GENERALLY DECEASED POPS IN THE VERY NEAR TERM IN PARTS
OF THE NORTHWEST...AND TRIED TO SURROUND THE ONGOING PRECIPITATION
IN THE CENTRAL WITH SLIGHTLY HIGHER POPS. PRECIPITATION AMOUNTS
HAVE GENERALLY BEEN A TRACE TO 0.01...SO DO NOT EXPECT MUCH
ACCUMULATION WITH THIS INITIAL ROUND.

PRECIPITATION TYPE REMAINS A BIT CHALLENGING...WITH SURFACE
TEMPERATURES SLOWLY FALLING THIS EVENING WHICH COULD LEAD TO A
PERIOD OF FREEZING RAIN. THE GOOD NEWS IS MODEL SOLUTIONS SUGGEST
A SLOW TEMPERATURE DECLINE...SO CURRENT THINKING IS ANY FREEZING
RAIN SHOULD BE VERY LIGHT AND BRIEF. THERE COULD ALSO BE A BRIEF
PERIOD OF SLEET AS COLDER AIR ARRIVES BEHIND A COLD FRONT LATER
THIS EVENING / TONIGHT. MODEL QPF IS LIGHT...SO AGAIN THINKING IS
AMOUNTS SHOULD BE VERY LIGHT.

&&

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

ISSUED AT 342 PM CST SAT NOV 22 2014

SHORT TERM CHALLENGE INVOLVES WINTER WEATHER AND WINDS. SURFACE
LOW ACROSS ALBERTA WILL TRACK EAST TONIGHT THROUGH SUNDAY.
CURRENTLY A WARM FRONT ACROSS SOUTHEAST MONTANA IS THE FOCUS FOR
RAIN FOR SOUTHWEST NORTH DAKOTA AS TEMPERATURES REMAIN IN THE
UPPER 30S TO MIDDLE 40S THIS AFTERNOON. BY THIS EVENING AS
TEMPERATURES COOL BUT BOUNDARY LAYER TEMPERATURES REMAIN ABOVE
FREEZING WILL SOME SOME POTENTIAL FOR A BRIEF PERIOD OF FREEZING
RAIN ACROSS THE WEST. TONIGHT THE RAIN CHANCES WILL CHANGE TO SNOW
CHANCES WITH A BRIEF PERIOD OF FREEZING RAIN POTENTIAL MAINLY
NORTH. BY SUNDAY MORNING THE COLD FRONT WILL APPROACH AND ALL
SNOW IS EXPECTED WITH INCREASING WINDS. DEBATED THE MERITS OF A
SNOW AND BLOWING SNOW ADVISORY ACROSS THE NORTH CENTRAL WHERE 1 OR
2 INCHES OF SNOW IS POSSIBLE HOWEVER DECIDED FOR A WIND ADVISORY
AS SUFFICIENT SNOW POTENTIAL IS LOW. WILL BREAK OFF THE NORTHERN
PORTION...ALONG HIGHWAY 2 AND NORTH AND MENTION SOME SNOW AND
BLOWING SNOW IN THE WIND ADVISORY FOR SUNDAY. OTHERWISE SUNDAY WILL
BE BLUSTERY WITH SNOW LIKELY NORTH AND CHANCE FOR SNOW SOUTH.
TEMPERATURES WILL FALL DURING THE DAY SUNDAY AND WINDS WILL BE 25
TO 45 MPH. WAS CONCERNED ABOUT A 9-11 MB PRESSURE RISE SUNDAY
AFTERNOON NORTH AS THE COLDER AIR ARRIVES. COULD GET SOME GUSTY
WINDS SUNDAY AFTERNOON FROM CROSBY TO MINOT TO ROLLA. SUNDAY NIGHT
WINDS WILL DIMINISH WEST CENTRAL AND MAY STILL BE A BIT GUSTY JAMES
RIVER VALLEY.

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

ISSUED AT 342 PM CST SAT NOV 22 2014

MEDIUM RANGE MODELS HAVE AGAIN SHIFTED FOR MID-LATE NEXT
WEEK...NOW TRENDING BACK COLDER AS BOTH THE 12Z GFS/ECMWF DEPICT
A NORTHWEST FLOW ALOFT VERSUS PREVIOUS RUNS WHICH SHOWED A BUILDING
UPPER LEVEL RIDGE INTO THE REGION. THIS WILL HAVE A DRAMATIC
IMPACT ON FORECAST TEMPERATURES WEDNESDAY-SATURDAY ALONG WITH SNOW
CHANCES.

REMOVED SNOW MENTION FOR MONDAY MORNING WITH WRAP AROUND MOISTURE
MORE OVER THE EASTERN DAKOTAS AND UPPER MIDWEST. SOME VERY LIGHT
SNOW/FLURRIES WILL BE POSSIBLE MONDAY AFTERNOON-EVENING WHEN
MODELS DEPICT A SUBTLE EMBEDDED S/WV MOVING THROUGH THE FLOW
ALOFT. THIS REPEATS ON TUESDAY WITH ANOTHER AREA OF LIGHT SNOW
MOVING FROM NORTHWEST TO SOUTHEAST ACROSS THE NORTHERN PLAINS
ASSOCIATED WITH AN AREA OF WEAK LOW PRESSURE. TEMPERATURES DO
REBOUND TUESDAY AS SOME WEAK WAA MOVES INTO THE WESTERN HALF OF
THE STATE AHEAD OF THE SFC LOW.

TRENDED THE THANKSGIVING HOLIDAY COLDER WITH THE PATTERN SHIFT TO
MORE NORTHWEST VERSUS ZONAL.

OF MAIN INTEREST AND A RECENT DEVELOPMENT WILL BE THE POSSIBILITY
OF ACCUMULATING SNOWFALL FROM MONTANA THROUGH SOUTHWEST NORTH
DAKOTA (POSSIBLY OVER THE ENTIRE SOUTHWESTERN HALF OF THE
STATE)...WHICH WOULD CREATE IMPACTS TO HOLIDAY TRAVEL. BOTH THE
12Z GFS/ECMWF ARE NOW SHOWING A QUASI-STATIONARY FRONTAL BOUNDARY
DRAPED NORTHWEST TO SOUTHEAST FROM NORTHERN MONTANA THROUGH
SOUTHWEST ND/WESTERN SOUTH DAKOTA. ALOFT A STRONG JET STREAK WILL
INTERACT WITH THE SFC BOUNDARY TO PRODUCE A SWATH OF ACCUMULATING
SNOWFALL UNDER STRONG THERMAL LIFT ALONG TO EAST OF THE FRONT.
THE MAIN DIFFERENCES BETWEEN THE GFS AND EC ARE PLACEMENT...WITH
THE GFS FARTHER NORTH AND EAST GIVING A GOOD SHOT OF SNOWFALL TO
WESTERN AND SOUTH CENTRAL PARTS OF THE STATE. THE ECMWF IS MORE
SOUTH AND WEST AND KEEPS MOST OF THE SNOW CONFINED TO THE
SOUTHWEST CORNER. CONFIDENCE LOW AT THIS POINT CONSIDERING THE
RATHER SIGNIFICANT MODEL FLIP FLOPS OVER THE PAST 48 HOURS.
SHOULD ALSO NOTE THE 12Z GEM IS VERY SIMILAR TO THE ECMWF. WILL
CONTINUE TO MONITOR...AND WILL NOT HIGHLIGHT IN ANY PRODUCTS AT
THIS TIME.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1254 AM CST SUN NOV 23 2014

VERY LIGHT RAIN IS POSSIBLE EARLY THIS MORNING FROM KBIS TO KJMS
AHEAD OF A STRONG COLD FRONT. VFR CONDITIONS WILL PREVAIL
INITIALLY...HOWEVER MVFR LEVEL CLOUDS WILL MOVE INTO WESTERN NORTH
DAKOTA AT KISN AT OR SHORTLY AFTER 06Z...AND SPREAD SOUTH AND EAST
ACROSS THE STATE. A COLD FRONT MOVES INTO THE NORTHWEST PART OF THE
STATE AT KISN AROUND 09Z...AND SWEEPS SOUTHEAST. BEHIND THE FRONT
STRONG NORTHWEST WINDS WITH LIGHT SNOW AND BLOWING SNOW ARE EXPECTED
WITH MVFR CIGS SUNDAY.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 10 AM CST /9 AM MST/ THIS MORNING TO MIDNIGHT
CST /11 PM MST/ TONIGHT FOR NDZ001>005-009>013-017>023-031>035-
040>045.

&&

$$

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






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