Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 020602
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
102 AM CDT SAT AUG 2 2014

.UPDATE...
ISSUED AT 103 AM CDT SAT AUG 2 2014

AN EARLIER LINE OF THUNDERSTORMS FROM SOUTHERN SASKATCHEWAN TO
EASTERN MONTANA HAS DECREASED GREATLY IN THE PAST COUPLE OF HOURS.
THE ASSOCIATED MID LEVEL SHORTWAVE IS PROGGED TO CONTINUE MOVING
SOUTHEAST ACROSS NORTHERN NORTH DAKOTA DURING THE OVERNIGHT HOURS.
THUS REDUCED PRECIP CHANCES IN THE NORTHWEST AND NORTH CENTRAL TO NO
MORE THAN 20 PERCENT CHANCE. THE MID LEVEL DISTURBANCE IS
THERE...BUT THE UPPER LEVEL SUPPORT FOR IT IS WEAK OVER NORTH
CENTRAL NORTH DAKOTA.

THE ISOLATED CONVECTION IN THE FAR SOUTH CENTRAL -
SIOUX/EMMONS/MCINTOSH COUNTIES - CONTINUED MOVING SOUTH INTO SOUTH
DAKOTA. KEPT SOME SLIGHT CHANCES OF PRECIPITATION THERE FOR A COUPLE
MORE HOURS.

ALSO ADDED A MENTION OF PATCHY FOG IN THE SOUTHWEST AND SOUTH
CENTRAL. DEWPOINT TEMPERATURES WERE REMAINING HIGHER - IN THE LOW TO
MID 60S IN SOME AREAS - AND WITH REPORTS OF AROUND 1 INCH OF RAIN
WITH THE EVENING THUNDERSTORMS IN THE SOUTH CENTRAL...COMBINED WITH
LIGHT WINDS...GOOD INGREDIENTS FOR FOG AHEAD OF A COLD FRONT THAT IS
PROGGED TO ENTER NORTHERN NORTH DAKOTA EARLY THIS MORNING.

UPDATE ISSUED AT 934 PM CDT FRI AUG 1 2014

THE MID LEVEL SHORTWAVE IN SOUTHERN SASKATCHEWAN LOOKS TO HAVE
PHASED WITH ANOTHER DISTURBANCE ASSOCIATED WITH EARLIER CONVECTION
IN WESTERN MONTANA...ACCORDING TO THE LATEST WATER VAPOR SATELLITE
IMAGERY. THE RESULT IS A SOUTHWARD EXPANSION OF THUNDERSTORMS
ALONG THE LEADING EDGE OF THE WAVES.

GRIDDED FORECASTS WERE UPDATED TO MOVE PRECIPITATION THROUGH
NORTHWESTERN NORTH DAKOTA A FEW HOURS EARLIER THAN PREVIOUSLY
FORECAST. THAT MADE THE TRANSITION TO AFTERNOON CONVECTION EAST OF
U.S. 83 DIFFICULT TO PORTRAY IN THE FORECAST. SO UPDATES TO
TOMORROWS FORECAST WERE ALSO MADE AS ANOTHER MID LEVEL SHORTWAVE
IS EXPECTED TO PASS OVER THE AREA SATURDAY AFTERNOON.

UPDATE ISSUED AT 712 PM CDT FRI AUG 1 2014

UPDATES THIS EVENING WILL FOCUS ON THUNDERSTORM CHANCES AS A
PASSING MESOSCALE CONVECTIVE VORTEX PAIRS WITH AFTERNOON
INSTABILITY TO SUPPORT AN AREA OF THUNDERSTORMS OVER SOUTH CENTRAL
NORTH DAKOTA. BY SUNRISE...A SECOND MCV WILL MOVE THROUGH
WILLISTON ON ITS WAY TO THE JAMES RIVER VALLEY BY SUNSET SATURDAY.
THERE IS A RISK FOR SEVERE STORMS SATURDAY AFTERNOON ASSOCIATED
WITH THIS SECOND MCV.

&&

.SHORT TERM...(THIS AFTERNOON THROUGH SATURDAY AFTERNOON)

ISSUED AT 333 PM CDT FRI AUG 1 2014

FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE THUNDERSTORM
CHANCES THROUGH THE PERIOD.

CURRENTLY...SURFACE LOW PRESSURE CENTERED OVER FAR SOUTHWEST
NORTH DAKOTA/NORTHWESTERN SOUTH DAKOTA...WITH A FRONTAL BOUNDARY
STRETCHED FROM WESTERN SOUTH DAKOTA BACK NORTHWEST ACROSS EASTERN
MONTANA. NORTHWEST FLOW ALOFT WITH MID LEVEL S/WV IMPULSES MOVING
SLOWLY SOUTHEAST ACROSS THE REGION. ONE OF THESE DISTURBANCES IS
INTERACTING WITH THE BOUNDARY TO TRIGGER A FEW SHOWERS/ISOLATED
THUNDERSTORMS ALONG TO SLIGHTLY WEST OF THE MISSOURI RIVER THIS
AFTERNOON. MID LEVEL CAPPING INVERSION HOLDING CONVECTION AT BAY
AT THE MOMENT ELSEWHERE...AND ALSO PREVENTED ONGOING CONVECTION
FROM STRENGTHENING.

CURRENT VORT MAX ACROSS CENTRAL NORTH DAKOTA COUPLED WITH
INCREASING MLCAPE ALONG THE SURFACE BOUNDARY MAY OVERCOME THE MID
LEVEL INVERSION TO TRIGGER A FEW SCATTERED STORMS LATE TODAY INTO
THIS EVENING...CURRENTLY EXPECTED ACROSS THE SOUTHWEST AND SOUTH
CENTRAL NEAR TO AHEAD OF THE MID LEVEL IMPULSE. WHILE WIDESPREAD
SEVERE WEATHER IS NOT ANTICIPATED...ENOUGH INSTABILITY PRESENT AND
SUFFICIENT 0-6KM SHEAR FOR THE POSSIBILITY OF A FEW ORGANIZED
UPDRAFTS AND THUS A SMALL THREAT FOR LARGE HAIL. ALSO...CIGS AT
AROUND 8-10K FEET AGL OR ABOVE WILL ELEVATE THE CHANCE FOR A FEW
STRONGER WIND GUSTS WITH ANY STORMS.

ANOTHER EMBEDDED S/WV SPINNING OVER SOUTHWESTERN
SASKATCHEWAN...IS PROJECTED TO CONTINUE SLOWLY SOUTH AND EAST
INTO NORTHWEST/NORTH CENTRAL ND LATER THIS EVENING AND
OVERNIGHT...SPARKING ADDITIONAL SHOWERS/THUNDERSTORMS WHICH LOOK
TO CONTINUE PAST DAYBREAK SAT MORNING OVER PORTIONS OF
CENTRAL/EASTERN ND. AREA OF ASSOCIATED SFC LOW PRESSURE WILL
ACCOMPANY THE MID LEVEL WAVE...WITH BOTH ADVERTISED TO LINGER OVER
EASTERN PORTIONS OF THE STATE MID TO LATE AFTERNOON BEFORE EXITING
SOUTHEAST IN THE EVENING. GIVEN THIS FORCING AND THE
INSTABILITY/SHEAR PARAMETERS...A FEW STRONGER STORMS WILL BE
POSSIBLE ACROSS EASTERN ND DURING PEAK HEATING HOURS SATURDAY
AFTERNOON/EVENING...MAINLY EAST OF HIGHWAY 83.

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

ISSUED AT 333 PM CDT FRI AUG 1 2014

A RETURN TO A MORE ACTIVE WEATHER PATTERN WILL HIGHLIGHT THE
EXTENDED FORECAST.

12Z MODELS REMAIN IN GOOD AGREEMENT ON AN UPPER LEVEL RIDGE
CENTERED ACROSS THE INTERMOUNTAIN WEST THIS WEEKEND...SLOWLY
BREAKING DOWN WITH A TRANSITION TO NEAR ZONAL FLOW EARLY NEXT
WEEK. THIS PATTERN SHIFT WILL SEE DAILY CHANCES FOR THUNDERSTORMS
ASSOCIATED WITH IMPULSES PROPAGATING ALONG THE NORTHERN PERIPHERY
OF THE RIDGE AND EMBEDDED WITHIN THE ZONAL FLOW. TEMPERATURES WILL
BE NEAR AVERAGE...HIGHS IN THE 80S AND LOWS 55-65.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 103 AM CDT SAT AUG 2 2014

BEGAN KISN AT 06Z WITH VCTS UNTIL 07Z AS A LINE OF CONVECTION MOVES
THROUGH THE KISN TAF AREA. THE INTENSITY OF THE LINE HAD WANED
GREATLY IN THE PAST COUPLE OF HOURS. THE MID LEVEL DISTURBANCE
ASSOCIATED WITH THE CONVECTION IS STILL PROGGED TO MOVE
EASTWARD...BUT THERE REMAINS CONSIDERABLE UNCERTAINTY WHETHER ANY
PORTION OF THE CONVECTIVE CELLS WILL MAINTAIN ENOUGH INSTABILITY TO
HOLD TOGETHER. KEPT A MENTION OF VCSH AT KMOT BUT NONE AT KBIS.

ADDED MENTION OF MVFR VSBYS IN FOG AT KDIK AND KBIS FROM 09Z-13Z
WITH LIGHT WINDS...PLENTY OF LOW LEVEL MOISTURE...AHEAD OF A COLD
FRONT.

OTHERWISE THE MID LEVEL DISTURBANCE WILL BE IN THE KJMS VICINITY BY
AROUND 17Z FOR A BETTER CHANCE OF THUNDERSTORMS AT KJMS THIS
AFTERNOON.

&&

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

$$

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






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