Area Forecast Discussion
Issued by NWS Bismarck, ND

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529
FXUS63 KBIS 161123
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
623 AM CDT SAT MAY 16 2015

.UPDATE...
ISSUED AT 615 AM CDT SAT MAY 16 2015

AT 615 AM CDT A LARGE AREA OF RAIN WAS MOVING NORTH FROM
DICKINSON...WITH SCATTERED SHOWERS FROM UNDERWOOD THROUGH
CARRINGTON. ANOTHER AREA OF SHOWERS WAS MOVING INTO OAKES. THE
NOSE OF THE NEXT BATCH OF RAIN WAS ADVANCING NORTH MIDWAY BETWEEN
RAPID CITY AND ABERDEEN SOUTH DAKOTA.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 445 AM CDT SAT MAY 16 2015

MAIN CONCERNS IN THE SHORT TERM INCLUDE TIMING AND AREAL COVERAGE OF
RAIN SHOWERS AND THUNDERSTORMS...AND RESULTING PRECIP AMOUNTS ACROSS
WESTERN AND CENTRAL NORTH DAKOTA.

CHALLENGING FORECAST TODAY REGARDING TIMING AND COVERAGE/CHANCES OF
RAIN SHOWERS AND THUNDERSTORMS. THE HRRR HAD LOOKED THE BEST FOR
BRINGING RAIN SHOWERS NORTHWARD INTO NORTH DAKOTA FROM SOUTH
DAKOTA...BUT WITH TIME THIS MORNING THE NORTHWARD-MOVING LEADING
EDGE OF RAIN SHOWERS CONTINUED TO SLOW...AND NONE OF THE MODELS HAD
A GOOD HANDLE ON THE TIMING FROM FRIDAY EVENING THROUGH 4 AM CDT.
THAT SAID...THE CURRENT RADAR LOOPS DO INDICATE THE NORTHWARD
MOVEMENT OF THE PRECIPITATION...AND ALSO A MORE ROBUST LINE OF
THUNDERSTORMS OVER EASTERN SOUTH DAKOTA MOVING NORTHWARD.

THE MODELS INDICATE THE UPPER LEVEL AND LOW LEVEL LOW PRESSURE
CENTERS OVER WYOMING THIS MORNING. BY THIS EVENING THE UPPER LEVEL
LOW LIFTS NORTHWARD INTO MONTANA...BUT THE SURFACE LOW REMAINS OVER
WYOMING/SOUTH DAKOTA. ALL MODELS ARE SUGGESTING A CLEARING/DRYING
AREA DEVELOPING SOMEWHERE OVER SOUTH DAKOTA AND INTO SOUTHERN NORTH
DAKOTA...AND MODELS VARY ON WHETHER ITS PLACEMENT WILL BE IN THE
WESTERN DAKOTAS OR CENTRAL PARTS. DURING THE AFTERNOON IT IS
EXPECTED THAT THE INITIAL PUSH OF PRECIPITATION WILL LIFT NORTHWARD
TOWARDS CANADA...AND THAT THE CLEARING AREA TO THE SOUTH WILL ALLOW
ENHANCED SURFACE HEATING AND DEVELOPMENT OF A LINE OF THUNDERSTORMS
BY AROUND MID-AFTERNOON. CONFIDENCE IS LOW FOR HOW MUCH CLOUD COVER
WILL DISSIPATE AND WHETHER ANY LINE OF STRONG CONVECTION WILL
DEVELOP. REGARDLESS...FORECAST CAPES AND BULK SHEAR SUPPORT
THE POSSIBILITY OF SEVERE STORMS THIS AFTERNOON/EVENING...MAINLY
OVER CENTRAL NORTH DAKOTA.

TOTAL RAIN AMOUNTS THROUGH SATURDAY NIGHT RANGE FROM AROUND 0.5
INCH TO 1.25 INCHES.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 445 AM CDT SAT MAY 16 2015

NOTE...WITH THE RISK OF SEVERE WEATHER TODAY IT WOULD NOT BE
PRUDENT TO POST ANY WIND...WINTER...OR FROST / FREEZE HEADLINES AT
THIS TIME AS IT WOULD LEAD TO CONFUSE THE ISSUES. I DO EXPECT THE
NEED FOR A WIND ADVISORY...WINTER WEATHER ADVISORY (NORTHEAST
FORECAST AREA)...AND FROST ADVISORY / FREEZE WARNING...AT VARIOUS
POINTS OVER THE NEXT SEVERAL DAYS.

FORECAST CHALLENGES AND HAZARDS CONTINUE INTO THE LONG TERM. THEY
INCLUDE THUNDER...HEAVY RAIN...SNOW...AND TEMPERATURES IN THE 20S.

AS WE TRANSITION SUNDAY FROM POCKETS OF INSTABILITY TO A GENERAL
WIDESPREAD LIFTING...THE RISK OF THUNDERSTORMS WILL BE CONFINED
TO THE JAMES RIVER VALLEY. FOR THE REST OF THE AREA A STEADY
RAIN...HEAVY AT TIMES AS THE H5 LOW APPROACHES...WILL OCCUR.

COLDER AIR WORKS IN ON STRONG NORTHWEST WINDS 25 TO 45 MPH AND BY
SUNDAY EVENING THE RAIN NORTH WILL BE MIXING WITH SNOW. WITH H8
TEMPERATURES FALLING TO -4 DEGREES C THE MIX WILL CHANGE TO ALL
SNOW NORTH...WITH A MIX SOUTH. RUNNING THE QUANTITATIVE
PRECIPITATION FORECAST ALONG WITH SNOW RATIOS OFF THE NAM (THE
MOST REASONABLE BASED ON EXPECTED THERMAL PROFILES) A FEW TO
SEVERAL INCHES OF SNOW RESULTS FROM BOTTINEAU COUNTY THROUGH
ROLETTE AND DOWN INTO NORTHERN PIERCE...THAT ON GRASSY SURFACES.
EVEN UNDER CLOUDCOVER DAYBREAK TEMPERATURES MONDAY MORNING WILL BE
WITHIN SEVERAL DEGREES EITHER SIDE OF FREEZING. BY MID DAY MONDAY
THE PRECIPITATION ENDS OVER THE FORECAST AREA BUT THE STRONG
NORTHWEST WINDS CONTINUE.

WITH PARTLY CLOUDY SKIES MONDAY NIGHT LOWS ARE FORECAST TO BE IN
THE 27 TO 34 DEGREE RANGE.

BEYOND THAT THE STORM TRACK SHIFTS SOUTH...OVER NEBRASKA AND SOUTH
DAKOTA WITH THE NORTHERN EXTENT OF THE PRECIPITATION
EXTENDING...PERIODICALLY...INTO SOUTHERN NORTH DAKOTA. THROUGH
THE REST OF THE LONG TERM INSTABILITY AND CAPE ARE VERY LIMITED SO
OPTED TO NOT INCLUDE THUNDER IN ANY PERIOD BEYOND SUNDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 615 AM CDT SAT MAY 16 2015

THE MAIN CONCERN IS THE SHOWER / THUNDERSTORM CHANCES AND THE
ASSOCIATED MVFR CEILINGS / VISIBILITIES. EXPECT INCREASING
CHANCES FOR SHOWERS THROUGH THE DAY...WITH INCREASING CHANCES FOR
THUNDERSTORMS ESPECIALLY CENTRAL AND EASTERN NORTH DAKOTA TAF
SITES. AFTER 03Z ON THE 17TH THUNDER CHANCES WILL DECREASE AS
WIDESPREAD RAIN MOVES IN WITH MVFR CONDITIONS.

&&

.HYDROLOGY...
ISSUED AT 445 AM CDT SAT MAY 16 2015

FORECAST PRECIPITATION AMOUNTS THROUGH SUNDAY NIGHT RANGE BETWEEN
ONE AND THREE INCHES. CONFIDENCE IS LOW REGARDING TIMING AND
PLACEMENT OF RAIN SHOWERS AND THUNDERSTORMS...THUS AFFECTING
EXPECTED RAINFALL AMOUNTS. FUTURE FORECASTS MAY NEED TO INCLUDE AN
AREAL FLOOD WATCH...ESPECIALLY IF FORECAST CONFIDENCE INCREASES.

&&

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

$$

UPDATE...JPM
SHORT TERM...JV
LONG TERM...JPM
AVIATION...JV/JPM
HYDROLOGY...JV/JPM



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