Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 312040
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
340 PM CDT SUN MAY 31 2015

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 243 PM CDT SUN MAY 31 2015

MAIN FORECAST ISSUES IN THE SHORT TERM PERIOD WILL BE AVIATION
ISSUES TONIGHT INTO MONDAY MORNING...MAINLY CEILING. THEN
THUNDERSTORM CHANCES MONDAY AFTERNOON.

CURRENTLY...SCATTERED SHOWERS WERE EXITING THE SOUTHEAST CWA THIS
AFTERNOON. ISOLATED SHOWERS IN THE NORTH CENTRAL WERE DISSIPATING.
ANTICIPATE WE WILL BE ABLE TO START OUT WITH A DRY FORECAST THIS
AFTERNOON. MESOSCALE MODELS DO INDICATE SOME LIGHT REFLECTIVITIES
HANGING AROUND OUR EASTERN FORECAST AREA THIS EVENING. DOUBT MUCH
IF ANYTHING WILL REACH THE GROUND.

CLOUDS REMAINED ACROSS MUCH OF CENTRAL NORTH DAKOTA...WITH BREAKS
FINALLY ACROSS THE FAR WEST. NORTHEAST NORTH DAKOTA HAS REMAINED
NEARLY CLOUD FREE ALL DAY.

TONIGHT...HRRR CLOUD LAYERS INDICATE MVFR DECK CURRENTLY OVER
SOUTHWEST NORTH DAKOTA DIMINISHING. NARRE PROBABILITIES SHOW LOW
PROBABILITY OF MVFR DECK REMAINING OVER SOUTHWEST NORTH DAKOTA
THIS EVENING AND EVENTUALLY LIFTING NORTHWARD. NAM/GFS 925MB RH
INCREASE TONIGHT ACROSS WESTERN AND CENTRAL NORTH DAKOTA BUT
BUFKIT SOUNDINGS ARE NOT AS IMPRESSIVE WITH LOW STRATUS AS ONE
MIGHT THINK. WE DO GET A GOOD LOW LEVEL JET DEVELOPING TONIGHT
WITH A BIT OF A SOUTHWEST COMPONENT AFTER MIDNIGHT. SO MAYBE
ENOUGH MIXING AND DRIER AIR ALOFT TO INHIBIT THE FORMATION OF A
WIDESPREAD STRATUS LAYER TONIGHT.

MONDAY...SOUTHERLY FLOW CONTINUES INTO MONDAY WITH INCREASING LOW
LEVEL MOISTURE. GFS PRECIPITABLE H2O INCREASES TO OVER 1.25IN FROM
WEST CENTRAL INTO NORTH CENTRAL NORTH DAKOTA BY LATE AFTERNOON
MONDAY. SHOULD BE WARM AND HUMID ACROSS THE WEST BY MONDAY
AFTERNOON WITH HIGHS IN THE MIDDLE 80S. BY LATE AFTERNOON WE
SHOULD BE SEEING 500-1000J/KG MUCAPE ACROSS WEST CENTRAL INTO
NORTH CENTRAL NORTH DAKOTA WITH AROUND 40KTS OF 0-6KM BULK SHEAR.
THERE IS SOME DIRECTIONAL SHEAR ALSO FOR A BRIEF PERIOD LATE
AFTERNOON INTO EARLY EVENING. MODELS INDICATE A SHORTWAVE TROUGH
TRACKING ACROSS SOUTHERN CANADA MONDAY AFTERNOON...IN ADDITION TO
WEAK SHORTWAVE ENERGY WORKING THROUGH THE UPPER RIDGE OVER
EASTERN MONTANA. WE SHOULD BE UNSTABLE ENOUGH ACROSS THIS REGION
TO SPARK A FEW THUNDERSTORMS MONDAY AFTERNOON. IF THIS DOES
OCCUR...ENOUGH SHEAR/INSTABILITY IN PLACE THAT SOME COULD BE
SEVERE. WILL ADD A MENTION OF SEVERE 21Z- 00Z MONDAY AFTERNOON.
THREAT FOR STRONG TO SEVERE STORMS WILL CONTINUE INTO THE LONG
TERM PERIOD.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 243 PM CDT SUN MAY 31 2015

AN ACTIVE WEATHER PATTERN WILL CONTINUE TO BE THE MAIN HIGHLIGHT
IN THE LONG TERM PERIOD...WITH A GOOD POTENTIAL FOR SEVERE WEATHER
MONDAY NIGHT WEST INTO CENTRAL...AND AGAIN TUESDAY AND TUESDAY NIGHT
OVER ALL OF WESTERN AND CENTRAL NORTH DAKOTA. A PERSISTENT LONGWAVE
TROUGH OVER THE WEST COAST WILL SEND SEVERAL WAVES OF UPPER LEVEL
IMPULSES ACROSS NORTH DAKOTA THROUGH THE LONG TERM PERIOD. MONDAY
EVENING THROUGH WEDNESDAY THE MODELS DEPICT A NEARLY CONTINUOUS
STREAM OF THESE UPPER LEVEL SHORTWAVES MOVING NORTHEASTWARD ACROSS
THE STATE. WIDESPREAD SHOWERS AND THUNDERSTORMS ARE EXPECTED
BEGINNING MONDAY NIGHT AND CONTINUING THROUGH WEDNESDAY MORNING.
WEDNESDAY NIGHT THROUGH NEXT WEEKEND THE UPPER LEVEL SHORTWAVES
BECOME A BIT MORE LESS FREQUENT...BUT THIS WILL KEEP THE CHANCE OF
SHOWERS AND THUNDERSTORMS IN THE FORECAST EACH DAY.

MONDAY NIGHT:

LATE MONDAY AFTERNOON A SURFACE LOW IS OVER THE CENTRAL MT/WY BORDER
WITH A WARM FRONT EXTENDING NORTHEASTWARD ACROSS THE FAR NORTHWEST
CORNER OF NORTH DAKOTA AND INTO SOUTHWESTERN MANITOBA. A STRONG LOW
LEVEL JET IS ALREADY ESTABLISHED THROUGH CENTRAL/EASTERN NE/SD/ND
AND EXTENDS INTO MANITOBA. THE BEST FORCING IN NORTH DAKOTA IS OVER
THE NORTHWEST NEAR THE SURFACE WARM FRONT...WHERE THE WESTERN EXTENT
OF THE LOW LEVEL JET IS COINCIDENT WITH THE SURFACE WARM FRONT. THIS
IS THE TIME THAT THE VERY STRONG CAPE AXIS BUILDS NORTHWARD ALONG
THE MT/ND BORDER. 0-6KM BULK SHEAR VALUES OF 35-45 KTS IS ALREADY
ESTABLISHED ACROSS THE NORTHERN PLAINS. ADDITIONAL UPPER LEVEL
FORCING ARRIVES IN EASTERN MONTANA IN THE FORM OF A STRONG UPPER
LEVEL SHORTWAVE MOVING NORTHEAST ACROSS THE ROCKIES INTO MONTANA.
EXPECT THAT MONDAY AFTERNOON SCATTERED THUNDERSTORMS...SOME
SEVERE...IN EASTERN MONTANA WILL HAVE SPREAD NORTHEAST ACROSS THE
NORTHWEST PART OF NORTH DAKOTA AND INTO SOUTHERN SASK/MAN.

MONDAY EVENING AND NIGHT...THE SURFACE LOW DEVELOPS/MOVES EAST INTO
THE WESTERN DAKOTAS...WITH THE WARM FRONT AXIS EXTENDING FROM
WESTERN NORTH DAKOTA NORTHEASTWARD TOWARDS THE WINNIPEG AREA BY
DAYBREAK TUESDAY. THE LOW LEVEL JET AXIS ALSO MOVES EASTWARD ACROSS
THE DAKOTAS MONDAY NIGHT...WITH THE WESTERN EDGE OF THE LLJ IN THE
RED RIVER VALLEY BY DAYBREAK TUESDAY. THOUGH MONDAY NIGHT THE BULK
SHEAR AND MOST UNSTABLE CAPE VALUES DECREASE...BUT STILL REMAIN
POTENT...WITH VIGOROUS UPPER LEVEL SHORTWAVE ENERGY MAINTAINING
STRENGTH AS IT MOVES NORTHEASTWARD. EXPECT THAT THE SCATTERED
THUNDERSTORMS LATE MONDAY AFTERNOON AND EARLY EVENING IN THE
NORTHWEST WILL BECOME MORE NUMEROUS AND SPREAD/EXPAND EASTWARD INTO
CENTRAL NORTH DAKOTA. THE THREAT OF SEVERE STORMS WILL PERSIST
THROUGH MUCH OF THE NIGHTTIME PERIOD.

TUESDAY AND TUESDAY NIGHT:

THE SURFACE LOW/TROUGH THAT IS FORECAST TO BE OVER THE WESTERN
DAKOTAS BY DAYBREAK TUESDAY...AND IS PROGGED TO MOVE EASTWARD INTO
THE CENTRAL DAKOTAS BY TUESDAY EVENING. AS THIS OCCURS...THE
ASSOCIATED WARM FRONTAL BOUNDARY BECOMES ESTABLISHED IN AN EAST-WEST
FASHION ACROSS NORTHERN NORTH DAKOTA. THE BEST FORCING DURING THE
MORNING AND EARLY AFTERNOON BECOMES BEST ESTABLISHED ACROSS NORTHERN
NORTH DAKOTA...WHERE 0-6 KM BULK SHEAR VALUES INCREASE TO 40-55 KTS
COINCIDENT WITH THE WARM FRONT AS MOST UNSTABLE CAPE VALUES REACH 3-
6K+ IN A NORTH-SOUTH FASHION FROM CENTRAL NEBRASKA THROUGH SOUTH
CENTRAL NORTH DAKOTA ALONG THE NORTH-SOUTH SURFACE LOW/TROUGH. BY
LATE AFTERNOON A DRY SLOT THAT DEVELOPS DURING THE DAY FROM WY TO
WESTERN NE/SD REACHES SOUTHWEST INTO SOUTH CENTRAL NORTH DAKOTA.
EXPECT ONGOING STRONG AND SOME POSSIBLY SEVERE DURING THE MORNING
AND EARLY AFTERNOON TO BE MORE NUMEROUS NORTH THAN SOUTH. THEN AS
THE LATE AFTERNOON DRY SLOT MEETS UP WITH THE NORTH-SOUTH LOW/TROUGH
EXPECT QUICK DEVELOPMENT OF A NORTH/SOUTH LINE OF STRONG/SEVERE
THUNDERSTORMS OVER THE CENTRAL DAKOTAS. THIS MORE FOCUSED LINE OF
STORMS IS EXPECTED TO MOVE EAST THROUGH THE OVERNIGHT HOURS TUESDAY
NIGHT.

WEDNESDAY:

THE EAST-WEST WARM FRONTAL BOUNDARY THAT BECOMES ESTABLISHED ACROSS
NORTHERN NORTH DAKOTA TUESDAY MOVES SOUTHEAST ACROSS NORTH DAKOTA AS
A COLD FRONT LATE TUESDAY NIGHT/EARLY WEDNESDAY MORNING. SCATTERED
SHOWERS AND THUNDERSTORMS ARE EXPECTED WEDNESDAY...BUT THE THREAT OF
CHANCES OF SEVERE WEATHER IS REDUCED GREATLY.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 243 PM CDT SUN MAY 31 2015

MVFR CEILING AT KDIK STILL HOLDING STRONG AT 20Z. MAY NEED TO
EXTEND MVFR THROUGH 21-21Z. ELSEWHERE VFR CEILINGS AND EXPECT VFR
CEILINGS THROUGH THE REMAINDER OF THE AFTERNOON AND INTO THIS
EVENING. A SOUTHEAST SURFACE FLOW WILL CONTINUE THROUGH THE
FORECAST PERIOD. SOME UNCERTAINTY ABOUT THE DEVELOPMENT OF STRATUS
LATE TONIGHT INTO MONDAY MORNING. CERTAINLY THINK THIS IS A
POSSIBILITY BUT WOULD LIKE TO SEE MORE INDICATORS BEFORE WE
MENTION MVFR-IFR CEILINGS. LOCAL CLIMATOLOGY TOOL INDICATES MVFR
CEILINGS WOULD HOLD OFF THROUGH THE NEXT 12 HOURS...SO WILL HEDGE
AND MENTION A SCATTERED MVFR-IFR LAYER ACROSS THE AREA AFTER 04-06
UTC AND LET LATER SHIFTS MONITOR TRENDS.

&&

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

$$

SHORT TERM...TWH
LONG TERM...JV
AVIATION...TWH


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