749
FXUS63 KBIS 160859
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
359 AM CDT SUN AUG 16 2026
KEY MESSAGES
- LOW CHANCES (20-30%) FOR THUNDERSTORMS SOUTHWEST THIS
AFTERNOON INTO EARLY THIS EVENING. A STRONG TO MARGINALLY
SEVERE STORM CAN NOT BE RULED OUT, BUT WIDESPREAD SEVERE
STORMS ARE NOT ANTICIPATED.
- LOW TO MEDIUM CHANCES (20-50%) FOR SHOWERS AND ISOLATED
THUNDERSTORMS TONIGHT. SEVERE STORMS ARE NOT EXPECTED.
- NEAR DAILY LOW TO MEDIUM CHANCES (20-50%) FOR HIT AND MISS
SHOWERS AND THUNDERSTORMS THROUGH THE WORK WEEK.
- SEASONABLE TEMPERATURES ARE EXPECTED TODAY AND THROUGH THE
UPCOMING WORK WEEK.
DISCUSSION
ISSUED AT 357 AM CDT SUN AUG 16 2026
A NORTHWEST UPPER LEVEL FLOW WILL REMAIN OVER THE FORECAST AREA
TODAY AND THROUGH THE UPCOMING WORK WEEK. CURRENTLY, A BROAD
UPPER LEVER RIDGE WAS LOCATED OVER THE WESTERN U.S. NUMEROUS
SHORTWAVES WERE PROPAGATING THROUGH THE RIDGE, WITH A COUPLE
TRACKING THROUGH THE NORTHERN ROCKIES. ANOTHER SHORTWAVE WAS
TRACKING THROUGH THE WESTERN CANADIAN PROVINCES, AND FINALLY, A
STRONG WAVE WAS DROPPING SOUTHEAST THROUGH NORTHERN CANADA
AROUND A DEVELOPING HUDSON BAY LOW.
THE INITIAL SHORTWAVE ENERGY MAY SPARK ISOLATED TO SCATTERED
THUNDERSTORMS OVER WESTERN ND THIS AFTERNOON. THE SOUTHWEST WILL
BECOME MODERATELY UNSTABLE WITH SB CAPES AROUND 1000-1500 J/KG.
BULK SHEAR, INITIALLY MODEST DOES INCREASE LATE THIS AFTERNOON
INTO THIS EVENING WITH 30 TO 40KTS OF SHEAR OVER THE AREA. A
COUPLE OF FORECAST SOUNDINGS IN THE FAR SOUTHWEST INDICATE A
MARGINALLY SEVERE TO SEVERE ATMOSPHERE MAY BE POSSIBLE. THE MAIN
ISSUE MAY BE TIMING OF SHORTWAVE ENERGY LINING UP WITH PEAK
INSTABILITY. BOTH ARE PRESENT, BUT IF THEY DON'T LINE UP WELL,
STRONG CONVECTION MAY NOT OCCUR. A LOOK AT THE LATEST CAMS SHOWS
MOST DO DEVELOP SOME CONVECTION OVER/NEAR THE SOUTHWEST LATE
THIS AFTERNOON INTO EARLY THIS EVENING. A FEW DO SHOW STRONGER
UPDRAFTS, WHILE OTHERS ARE PRETTY WEAK. THE MAIN HAZARD WOULD BE
SMALL HAIL. WILL CONTINUE TO MONITOR, BUT AT THIS TIME WILL NOT
MENTION SEVERE STORMS. BETTER CHANCES FOR STRONG TO SEVERE
STORMS REMAINS OVER WESTERN SOUTH DAKOTA.
LATER TONIGHT THE AFOREMENTIONED WESTERN CANADIAN WAVE AND IT'S
ATTENDANT SURFACE LOW, TRACKS ACROSS THE SOUTHERN CANADIAN
PRAIRIE PROVINCES. ITS SURFACE WARM FRONT, WHICH WAS LINGERING
OVER EASTERN MONTANA, AND ITS QUICKLY FOLLOWING COLD FRONT
TRACKS EAST ACROSS THE FORECAST AREA TONIGHT. SO WE HAVE THE
EARLY CONVECTION IN THE SOUTHWEST, THEN LATER CONVECTION
TRACKING NORTHEAST TO SOUTHWEST ACROSS THE FORECAST AREA. BY THE
TIME THE NORTHERN CONVECTION MAKES IT INTO THE STATE,
INSTABILITY WILL BE MINIMAL AND STRONG TO SEVERE STORMS ARE NOT
ANTICIPATED. THERE MAY NOT BE THAT MUCH IN THE WAY OF CONVECTION
AT ALL, WITH SCATTERED SHOWERS AND MAYBE SOME ISOLATED
THUNDERSTORMS.
FINALLY, THE NORTHERN CANADIAN SHORTWAVE DIVING SOUTH, CATCHES
UP WITH THE LEADING CYCLONE OVER SOUTHEAST NORTH DAKOTA BY
MONDAY AFTERNOON. CONVECTION TRACKING THROUGH THE AREA LATE
TONIGHT MAY LINGER OVER THE SOUTH CENTRAL AND INTO EASTERN ND
ON MONDAY MORNING. BY THE TIME THE NORTHERN FRONT CATCHES UP AND
HELPS TO INVIGORATE CONVECTION OVER EASTERN ND, IT IS FORECAST
TO BE OUT OF OUR NECK OF THE WOODS.
THUS AFTER ALL THIS, SOME STRONGER CONVECTION CAN NOT BE RULED
OUT LATER THIS AFTERNOON INTO EARLY THIS EVENING OVER THE
SOUTHWEST. LATER THIS EVENING AND OVERNIGHT, ADDITIONAL
ISOLATED TO SCATTERED SHOWERS TRACK SOUTHEAST ACROSS THE
FORECAST AREA, AND MAY LINGER INTO MONDAY MORNING IN THE SOUTH
CENTRAL AND JAMES RIVER VALLEY. IF CONVECTION DOES RE-INVIGORATE
MONDAY, IT LOOKS LIKE THE POTENTIAL FOR SEVERE STORMS WILL BE
SOUTHEAST OF THE FORECAST AREA.
WE COOL DOWN ON TUESDAY BEHIND THE CANADIAN COLD FRONT WITH
HIGHS MAINLY IN THE 70S. WE THEN SEE A WARM-UP WITH HIGHS
MAINLY IN THE 80S BY THURSDAY, THEN MID 70S TO MID 80S INTO THE
WEEKEND. WITH THE NORTHWEST UPPER FLOW REMAINING OVER THE AREA,
DAILY HIT AND MISS THUNDERSTORMS CHANCES WILL REMAIN IN THE
FORECAST BUT WITH LOW PREDICTABILITY IN TIMING AND PLACEMENT.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1155 PM CDT SAT AUG 15 2026
VFR CONDITIONS TO BEGIN THE 06Z TAF PERIOD AND MAINLY VFR
CONDITIONS EXPECTED THROUGH THE FORECAST PERIOD. WITH HIGH
PRESSURE OVER THE FORECAST AREA SUNDAY MORNING, LIGHT WINDS AND
MOSTLY CLEAR SKIES ARE EXPECTED. PATCHY FOG WILL BE A
POSSIBILITY ACROSS THE AREA. GUIDANCE IS NOT INDICATING MUCH FOR
FOG AT THIS TIME SO CONFIDENCE IS TOO LOW TO ADD TO ANY TAF
SITE. THERE WILL BE A LOW CHANCE FOR THUNDERSTORMS IN THE
SOUTHWEST THIS AFTERNOON, THEN TONIGHT, LOW CHANCES (20-30%) FOR
SHOWERS AND THUNDERSTORMS TRACK EAST ACROSS THE FORECAST AREA.
AT THIS TIME, MAY ADD A PROB30 TO WESTERN TAF SITES, BUT AGAIN,
CONFIDENCE IS TOO LOW FOR ANYTHING MORE AT THIS TIME. LIGHT
SURFACE FLOW TONIGHT. DURING THE DAY SUNDAY EXPECT WINDS
GENERALLY 12KTS OR LESS FROM THE NORTHWEST OVER CENTRAL AND FROM
THE SOUTH OVER WESTERN ND.
BIS WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...TWH
AVIATION...TWH
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