Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 041413
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
913 AM CDT FRI SEP 4 2015

.UPDATE...
ISSUED AT 902 AM CDT FRI SEP 4 2015

UPDATE TO BLEND OBSERVED RADAR TRENDS TO A TIME LAGGED ENSEMBLE OF
THE 10-12 UTC HRRR ITERATIONS WHICH HAVE A GOOD HANDLE OF ONGOING
CONVECTION THIS MORNING. SPC HAS MAINTAINED THE MARGINAL RISK FOR
SEVERE STORMS FOR THE TURTLE MOUNTAINS THROUGH THE JAMES RIVER
VALLEY AND POINTS EAST THIS AFTERNOON. THE 13 UTC RAP FORECAST
DEPICTS 1500-2000 J/KG OF ML CAPE AND 20-25 KTS OF DEEP LAYER
SHEAR THIS AFTERNOON ACROSS THE AFOREMENTIONED AREAS...SUPPORTING
THE MARGINAL RISK FOR POSSIBLY A SEVERE STORM OR TWO.
HOWEVER...THE RAP ALSO PROPAGATES THE MAIN FORCING MECHANISM OF
THE SHORTWAVE ACROSS CENTRAL SOUTH DAKOTA THIS MORNING INTO
NORTHEAST NORTH DAKOTA LATE THIS AFTERNOON. THUS...THE TIMING OF
THE WAVE SUGGESTS THE BEST POTENTIAL FOR STRONG TO SEVERE STORMS MAY
RESIDE NORTHEAST OF THE CWA.

UPDATE ISSUED AT 628 AM CDT FRI SEP 4 2015

SHOWERS CONTINUE TO LIFT SOUTH TO NORTH OVER THE AREA THIS
MORNING...WITH THE GREATEST COVERAGE AT THIS TIME OVER FAR
WESTERN NORTH DAKOTA. ANOTHER AREA CONTINUES TO DEVELOP OVER
PORTIONS OF SOUTH CENTRAL NORTH DAKOTA...WHILE A BROAD AREA OVER
CENTRAL SOUTH DAKOTA CONTINUES TO LIFT TOWARDS OUR REGION. FOR THE
MORNING UPDATE...HAVE TRIED TO TIME OUT THE MOTION/ARRIVAL OF
THESE STORMS BASED ON CURRENT TRENDS AND LATEST HRRR GUIDANCE AND
HAVE ADJUSTED POPS ACCORDINGLY. UPDATES HAVE BEEN SENT.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)

ISSUED AT 423 AM CDT FRI SEP 4 2015

FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE CHANCES FOR
SHOWERS AND THUNDERSTORMS THROUGH THE PERIOD. HEAVY RAIN POTENTIAL
FAR NORTHWEST THIS MORNING AND POSSIBLY ACROSS THE JAMES RIVER
VALLEY.

CURRENTLY...SOUTH-SOUTHWEST FLOW ALOFT. STRONG EMBEDDED S/WV
IMPULSE LIFTING ACROSS WESTERN SOUTH DAKOTA TOWARDS CENTRAL NORTH
DAKOTA RESULTING IN AN INCREASE IN COVERAGE AND INTENSITY IN
SHOWERS AND THUNDERSTORMS ACROSS PARTS OF THE NORTHERN PLAINS THE
PAST FEW HOURS. THE MOST FAVORED AREAS WILL BE ALONG A QUASI-
STATIONARY FRONTAL BOUNDARY DRAPED FROM SOUTHWESTERN NORTH DAKOTA
NORTHEAST THROUGH THE TURTLE MOUNTAINS...AND ACROSS MY NORTHWEST
NEAR A POST FRONTAL AXIS. ANOMALOUS MOISTURE SURGING INTO THE
NORTHERN PLAINS WITH LATEST WATER VAPOR LOOP INDICATING A WELL
DEFINED MID/UPPER LEVEL MOISTURE FEED FROM TROPICAL STORM FRED
SOUTHWEST OF BAJA CALIFORNIA. WARM MID-ATMOSPHERIC PROFILE
SUGGESTS A MORE LOCALIZED HEAVY RAIN THREAT VERSUS WIDESPREAD.
WILL CONTINUE TO MONITOR.

AS MENTIONED ABOVE...AND AS HIGH RES AND LATEST NAM MODEL
SUGGEST...NORTHWESTERN NORTH DAKOTA AND THE JAMES RIVER VALLEY
LOOK HAVE THE GREATEST POTENTIAL AT THIS TIME FOR HEAVY RAINFALL.
VIGOROUS CONVECTION OVER SOUTHEASTERN SASKATCHEWAN SHOWING SOME
SIGNS OF DEVELOPING SOUTH INTO MY NORTHWEST. CONVECTIVE COMPLEX
OVER CENTRAL SOUTH DAKOTA MOVING NORTH WHICH LATEST NAM AND HRRR
BRING INTO THE JAMES RIVER BASIN 12-15Z OR SO. VERY UNSEASONABLE
HIGH DEWPOINT TEMPERATURES OUT THERE IN THE 60S TO LOW 70S
CENTRAL AND EAST.

EMBEDDED WAVE CONTINUES TO LIFT NORTH-NORTHEAST TODAY AND EXPECT
CLEARING SKIES AND DECREASING CHANCES FOR SHOWERS/THUNDERSTORMS
FROM SOUTH TO NORTH IN THE WAVE`S WAKE THIS AFTERNOON. LATEST SPC
OUTLOOK MOVED THE SLIGHT RISK AREA INTO MAINLY THE RED RIVER
VALLEY OF EASTERN NORTH DAKOTA...SO OPTED TO REMOVE SEVERE WORDING
IN OUR PRODUCTS. MODELS HINTING AT LOW LEVEL STRATUS/FOG DEVELOPING
TONIGHT WITH LOW LEVEL MOISTURE REMAINING HIGH COUPLED WITH
FORECAST RAINFALL TODAY.

NEXT STRONG EMBEDDED WAVE LIFTS NORTH-NORTHEAST LATE TONIGHT INTO
SATURDAY...WITH INCREASING POPS WEST LATE TONIGHT THEN SPREADING
EAST AND NORTH ACROSS THE REMAINDER OF THE STATE DURING THE DAY
SATURDAY.

.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 359 AM CDT FRI SEP 4 2015

UPPER LEVEL TROUGH CLOSES OFF TOWARDS NORTHERN MONTANA THROUGH THE
NIGHT ON SATURDAY WITH PRECIPITATION CHANCES SLOWLY TAPERING OFF
THROUGH THE NIGHT FROM SOUTH TO NORTH. ON SUNDAY...GREATEST
CHANCES WILL BE RESTRICTED TO NORTHERN PORTIONS OF THE AREA AS
UPPER LOW STARTS TO WORK ITS WAY TOWARDS THE EAST/NORTHEAST ACROSS
THE SOUTHERN PRAIRIE PROVINCES. DRY CONDITIONS EXPECTED OVER MOST
LOCATIONS BY SUNDAY NIGHT. BREEZY/WINDY CONDITIONS EXPECTED ON
SUNDAY AS SYSTEM BECOMES STACKED.

MAINLY DRY CONDITIONS EXPECTED ON MONDAY WITH COOLING TREND
CONTINUING AS LOW CONTINUES ITS TRACK NORTH OF THE AREA. THIS WILL
BRING CONTINUED BREEZY CONDITIONS OVER NORTHERN LOCATIONS. MAINLY
DRY CONDITIONS EXPECTED THROUGH MID-WEEK WITH A GRADUAL WARMING
TREND EXPECTED AS RIDGE BUILDS OVER WESTERN CONUS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 902 AM CDT FRI SEP 4 2015

PATCHY FOG AND IFR STRATUS POTENTIAL THROUGH MID MORNING WITH
VERY HIGH BOUNDARY LAYER MOISTURE ACROSS THE REGION. WESTERN
TERMINALS WILL SEE -SHRA AND VCTS NOW THROUGH MID
MORNING...SPREADING EAST MID MORNING THROUGH THE AFTERNOON. AT
LEAST PARTIAL CLEARING EXPECTED FROM SOUTH TO NORTH TODAY INTO
THIS EVENING.

&&

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

$$

UPDATE...AYD
SHORT TERM...NH
LONG TERM...JJS
AVIATION...AYD


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