Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 240536
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1236 AM CDT SUN APR 24 2016

.UPDATE...
ISSUED AT 1225 AM CDT SUN APR 24 2016

TWEAKED PRECIPITATION CHANCES WITH THIS UPDATE. RAIN SHOWERS ARE
SLOW TO DEVELOP LATE TONIGHT. LATEST HIGH-RES DATA INDICATES A
SLIGHTLY DELAYED DEVELOPMENT OF PRECIPITATION COMPARED TO THE
PREVIOUS FORECASTS. THEREFORE DELAYED THE MENTION OF LIKELY
CHANCES TILL THIS MORNING. LOW LEVEL FRONTOGENESIS CONTINUES TO
STRENGTHEN TONIGHT...HOWEVER...THE MAIN UPPER LEVEL WAVE WAS STILL
LOCATED ACROSS SOUTH DAKOTA. THUNDERSTORMS STILL APPEAR POSSIBLE
ACROSS SOUTHERN NORTH DAKOTA. ISOLATED THUNDERSTORMS HAVE
DEVELOPED WEST OF THE BLACK HILLS IN ASSOCIATION WITH THE 700 MB
LOW.

UPDATE ISSUED AT 921 PM CDT SAT APR 23 2016

WIDELY SCATTERED SHOWERS NORTHEAST DECREASING. SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS APPROACHING THE SOUTHWEST. EXPECT
AROUND OR SHORTLY AFTER MIDNIGHT. CONTINUED BREEZY TO WINDY.

UPDATE ISSUED AT 636 PM CDT SAT APR 23 2016

DEEP LOW PRESSURE OVER WESTERN SOUTH DAKOTA AND HIGH PRESSURE
ACROSS MANITOBA WERE ENHANCING THE LOW LEVEL WINDS ACROSS NORTH
DAKOTA. MOST AREAS HAD EAST WINDS OF 20 TO 35 MPH WITH A FEW
SITES ABOVE 40 MPH. EXPECT THE WINDS TO CONTINUE TONIGHT. WATER
VAPOR CHANNEL SHOWS THE 700 MB UPPER LOW IN THE VICINITY OF WEST
CENTRAL WYOMING. SCATTERED THUNDERSTORMS HAVE DEVELOPED INTO SOUTH
CENTRAL MONTANA SOUTHEAST THROUGH EASTERN WYOMING. EXPECT THIS
AREA TO ROTATE NORTHEAST INTO SOUTHWEST NORTH DAKOTA LATE TONIGHT.
OTHERWISE FOR THE NEXT 6 HOURS OR SO LOOKING AT SOME INCREASING
CLOUDS AND A STEADY EAST WIND OF 20 TO 40 MPH.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 313 PM CDT SAT APR 23 2016

MAIN HIGHLIGHTS THROUGH SUNDAY AFTERNOON: RAINFALL AMOUNTS
ESPECIALLY LOCATIONS WHERE TOTALS EXCEED ONE INCH...A FEW STRONG
THUNDERSTORMS SOUTHWEST TONIGHT WITH POSSIBLE SMALL HAIL AND
GUSTY WINDS...AND POTENTIAL WIND ADVISORY TURTLE MOUNTAINS AND
VICINITY SUNDAY.

THE LATEST WATER VAPOR IMAGERY SHOWS A CLOSED UPPER LOW CIRCULATING
OVER FAR SOUTHEAST IDAHO WITH A DEEPENING SURFACE LOW
DOWNSTREAM...POSITIONED OVER NORTHEAST WYOMING. A WARM FRONT
EXTENDED FROM THIS LOW AND WAS DRAPED ALONG THE SOUTHERN BORDER.
WITH THIS WARM FRONT REMAINING JUST SOUTH OF OUR BORDER
TONIGHT/SUNDAY...AND THE UPPER LOW CATCHING UP WITH THE SURFACE
LOW AND BECOMING A VERTICALLY STACKED SYSTEM OVER CENTRAL SOUTH
DAKOTA...A WELL DEFINED DEFORMATION ZONE SETS UP OVER ALL OF
CENTRAL AND SOUTHERN NORTH DAKOTA LATER TONIGHT THROUGH SUNDAY.
FORCING/VERTICAL MOTION PER Q-VECTOR DIVERGENCE FIELD AND STEEP
MID LEVEL LAPSE RATES APPEAR MAXIMIZED BETWEEN INTERSTATE 94 AND
JUST SOUTH OF HIGHWAY 2. THIS SHOULD SET THE STAGE FOR PERIODS OF
HEAVIER RAINFALL AND HIGHEST RAINFALL TOTALS THROUGH SUNDAY.
EXPECT BETWEEN 1 AND 1.4 INCHES OF TOTAL RAINFALL THROUGH SUNDAY
NIGHT BETWEEN INTERSTATE 94 AND HIGHWAY 2.

THUNDERSTORM POTENTIAL REMAINS ELEVATED THROUGH THE PERIOD WITH
DECREASING CIN AS MOISTURE INCREASES THROUGH THE COLUMN AND
STEEPENING MID LEVEL LAPSE RATES. BEST CHANCES WILL BE TONIGHT
THROUGH SUNDAY MORNING...WITH SOUNDINGS BECOMING SATURATED AND
SHOWING RELATIVELY SKINNY OR NO CAPE FIELD. ENVIRONMENT SHOULD
TRANSITION MORE TOWARDS A HEAVY RAIN VERSUS CONVECTIVE IN NATURE.
SPC HAS MAINTAINED THE MARGINAL RISK FOR SEVERE THUNDERSTORMS IN
THE FAR SOUTHWEST TONIGHT. THINKING IS CONVECTION WOULD BEGIN AFTER
03Z PER LATEST HRRR AND GRADUALLY INCREASE OVERNIGHT INTO MID
MORNING SUNDAY.

GUSTY NORTHEAST WINDS WILL CONTINUE TONIGHT THROUGH SUNDAY ACROSS
ALL OF WESTERN AND CENTRAL NORTH DAKOTA. THE STRONGEST WINDS ARE
FORECAST ALONG AND NORTH OF HIGHWAY 2...WITH THE TURTLE MOUNTAINS
PINPOINTED FOR THE HIGHEST SUSTAINED WINDS OF AROUND 30 MPH AND
GUSTS TO 45 MPH. FUTURE SHIFTS CAN RE-EVALUATE FOR A POSSIBLE WIND
ADVISORY.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 313 PM CDT SAT APR 23 2016

THE VERTICALLY STACKED SYSTEM CONTINUES TO SLOWLY SHIFT EAST
SUNDAY NIGHT AND MONDAY WITH A GRADUAL DECREASE IN POPS. HOWEVER
THE ECMWF HAS BEEN CONSISTENTLY ADVERTISING HIGHER QPF AND COLDER
AIR ESPECIALLY ALONG AND SOUTH OF INTERSTATE 94 MONDAY. THUS HAVE
TRENDED POPS BETWEEN CHC/LIKELY WITH MOSTLY RAIN AND A LITTLE BIT
OF SNOW EXPECTED. SNOWFALL ACCUMULATIONS OF A COUPLE TENTHS POSSIBLE
SUNDAY NIGHT ACROSS THE WEST.

ANOTHER ROUND OF PRECIPITATION IS POSSIBLE TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT MAINLY ACROSS SOUTHERN NORTH DAKOTA. THE GFS AND
ECMWF CONTINUE TO BE AT ODDS IF THIS WILL OCCUR. THE GFS HAS BEEN
CONSISTENTLY SHOWING THE ABOVE...WHILE THE ECMWF IS NOT AS FAR
NORTH WITH THE PRECIPITATION SHIELD.

A BREAK IN THE PRECIPITATION THREAT IS POSSIBLE THURSDAY AND FRIDAY.
ANOTHER WET PERIOD SATURDAY BUT THE GFS AND ECMWF DIFFER ON PLACEMENT
OF THE PRECIPITATION AREA.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1225 AM CDT SUN APR 24 2016

MAIN HAZARDS TO AVIATION WILL BE GUSTY EAST WINDS AND A DEVELOPING
RAIN THAT WILL USHER IN WIDESPREAD IFR CONDITIONS SUNDAY. SURFACE
LOW PRESSURE ACROSS WESTERN SOUTH DAKOTA WILL MAINTAIN A STRONG
EASTERLY WIND FLOW THROUGH THE PERIOD. VFR EXPECTED THROUGH
08Z...THEN RAPIDLY DETERIORATING CONDITIONS TO IFR IN RAIN AND BR
AFTER 08Z. ISOLATED THUNDERSTORMS ARE POSSIBLE NEAR KBIS/KDIK/KJMS
THIS MORNING...BUT CONFIDENCE AND COVERAGE IS NOT HIGH ENOUGH TO
WARRANT ANYTHING OTHER THAN A VICINITY MENTION.

&&

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

$$

UPDATE...AJ
SHORT TERM...KS
LONG TERM...KS
AVIATION...AJ



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