629
FXUS63 KBIS 072105
AFDBIS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
405 PM CDT WED MAY 7 2025
KEY MESSAGES
- NEAR-CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED IN THE FAR
NORTHWEST TODAY.
- NEAR-CRITICAL TO CRITICAL FIRE WEATHER CONDITIONS ARE POSSIBLE
ACROSS PORTIONS OF WESTERN AND CENTRAL NORTH DAKOTA DURING THE
DAY THURSDAY (LOW HUMIDITY, BREEZY SOUTH WINDS, POSSIBLE DRY
THUNDERSTORMS).
- MAINLY DRY WITH WELL ABOVE AVERAGE TEMPERATURES AND
PERIODICALLY BREEZY CONDITIONS THROUGH THE WEEKEND. WIDESPREAD
NEAR-CRITICAL TO CRITICAL FIRE WEATHER CONDITIONS ARE PROBABLE
BOTH SATURDAY AND SUNDAY.
- TEMPERATURES TREND COOLER THROUGH NEXT WEEK, ALONG WITH
BETTER PRECIPITATION CHANCES AS WE TRANSITION TO AN ACTIVE
SOUTHWEST FLOW ALOFT.
DISCUSSION
ISSUED AT 355 PM CDT WED MAY 7 2025
CURRENTLY, DIRTY MID LEVEL RIDGE MOVING EAST ACROSS THE NORTHERN
PLAINS, WITH A SFC RIDGE OF HIGH PRESSURE EXTENDING FROM HUDSON
BAY SOUTHWEST THROUGH THE DAKOTAS. DEVELOPING LEE SIDE SFC
TROUGH ACROSS THE NORTHERN ROCKIES IN RESPONSE TO EMBEDDED WAVES
IN THE WAKE OF THE UPPER RIDGE CONTRIBUTING TO BREEZY SOUTHERLY
WINDS OVER WESTERN ND THIS AFTERNOON. NEAR-CRITICAL FIRE WEATHER
CONDITIONS NORTHWEST CONTINUE WHERE RH VALUES HAVE DROPPED TO
AROUND 25 PERCENT.
AFOREMENTIONED ENERGY WILL FLATTEN THE RIDGE TONIGHT, RESULTING
IN FLOW ALOFT TRANSITIONING TO QUASI-ZONAL. LEE SIDE SFC TROUGH
WILL NUDGE EAST TO OVER EASTERN MT/WESTERN MANITOBA DURING THE
DAY THURSDAY. WAA AHEAD OF THE TROUGH WILL SEE TEMPERATURES WARM
INTO THE UPPER 70S TO MID 80S TOMORROW, ALONG WITH SOUTHERLY
WINDS INCREASING AS THE PRESSURE GRADIENT TIGHTENS WITH THE
APPROACH OF THE SFC TROUGH. WITH A DRY AIRMASS REMAINING IN
PLACE, RH VALUES ARE PROJECTED TO DROP INTO THE MID TEENS TO
LOWER 20S MOST AREAS (LOWEST NORTH CENTRAL) RESULTING IN NEAR-
CRITICAL TO CRITICAL FIRE WEATHER CONDITIONS THU AFT/EVE FOR
PORTIONS OF WEST AND CENTRAL ND, WITH THE MORE DIRE CONDITIONS
IN THE NORTH CENTRAL. SEE FIRE WEATHER DISCUSSION BELOW FOR
DETAILS. MID LEVEL ENERGY RIDING OVER THE SFC TROUGH/FRONTAL
BOUNDARY WILL ALSO RESULT IN A CHANCE FOR LATE AFT/EVE ELEVATED
CONVECTION WEST AND NORTH CENTRAL. SOUNDINGS ARE DRY/INVERTED V
LOOKING, SO GUSTY WINDS WILL BE POSSIBLE WITH ANY ROBUST
UPDRAFT. SPC DRY T-STORM GUIDANCE BASICALLY MIRRORS OUR POPS.
QUASI-ZONAL FLOW REMAINS FOR FRIDAY, ALONG WITH A VERY DRY
BOUNDARY LAYER. SURFACE WINDS WILL BE RELATIVELY LIGHT HOWEVER,
SO DRY WEATHER AND SEASONABLY WARM TEMPERATURES ARE MAINLY
EXPECTED WITH LITTLE FIRE WEATHER CONCERNS.
MID LEVEL RIDGE REBUILDS OVER THE WEEKEND, WITH INCREASING
SOUTHERLY FLOW ACROSS THE DAKOTAS. TEMPERATURES WILL WARM WELL
INTO THE 80S TO LOWER 90S BOTH DAYS. LACK OF ANY DECENT MOISTURE
RETURN WILL MAINTAIN DRY BOUNDARY LAYER CONDITIONS, WITH PERCENT
MINIMUM HUMIDITY BOTH SAT AND SUN IN THE MID TEENS TO MID 20S.
WITH THE LIKELIHOOD OF SEEING BREEZY SOUTHERLY WINDS BOTH DAYS,
FIRE WEATHER CONCERNS RETURN.
FLOW ALOFT TRANSITIONS TO SOUTHWESTERLY EARLY NEXT WEEK, AND
WILL RESULT IN TEMPERATURES TRENDING COOLER ALONG WITH BETTER
PRECIPITATION CHANCES ACROSS THE NORTHERN PLAINS.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 130 PM CDT WED MAY 7 2025
BREEZY SOUTHERLY WINDS EXPECTED IN WESTERN ND TODAY, SPREADING
INTO PARTS OF NORTHERN NORTH DAKOTA TONIGHT. LLWS MAY IMPACT
PARTS OF WESTERN AND ESPECIALLY NORTHWESTERN ND LATE TONIGHT,
AND DID ADD A MENTION OF THIS IN KXWA TAF. OTHERWISE, VFR
CEILINGS AND VISIBILITY ARE EXPECTED THROUGH THE PERIOD.
FIRE WEATHER
ISSUED AT 355 PM CDT WED MAY 7 2025
NEAR CRITICAL FIRE WEATHER CONDITIONS WILL PERSIST NORTHWEST
THIS AFTERNOON THROUGH EARLY THIS EVENING. SUSTAINED WINDS TO
AROUND 25 MPH WILL COMBINE WITH PERCENT MINIMUM RELATIVE
HUMIDITY IN THE MID 20S. DO NOT EXPECT HUMIDITIES TO LOWER MUCH
MORE AS PEAK MIXING HAS ALREADY OCCURRED.
CRITICAL FIRE WEATHER CONDITIONS ARE POSSIBLE THURSDAY AFTERNOON
AND EVENING FOR PORTIONS OF WESTERN AND CENTRAL NORTH DAKOTA.
RELATIVE HUMIDITY VALUES ARE FORECAST TO DROP TO AS LOW AS 15
PERCENT, AND HAVE LEANED TOWARDS THE HRRR/RAP/NBM 10 PERCENT AS
MIXING SHOULD BE DECENT TO PROMOTE DRYING IN THE BOUNDARY LAYER.
WITH THE APPROACH OF A SFC TROUGH, SOUTH/SOUTHWESTERLY WINDS
SUSTAINED TO 25 MPH WITH GUSTS TO NEAR 40 MPH WILL SPREAD ACROSS
THE AREA AS THE PRESSURE GRADIENT TIGHTENS. IN ADDITION, THERE
IS A CHANCE FOR ISOLATED THUNDERSTORMS LATE IN THE AFTERNOON
AND EVENING AS A SUBTLE MID LEVEL WAVE INTERACTS WITH THE
AFOREMENTIONED SFC TROUGH/FRONTAL BOUNDARY. CAMS ARE IN DECENT
AGREEMENT WITH SOME ACTIVITY FIRING OFF. WITH THE DRY BOUNDARY
LAYER, ANY CONVECTION WILL BE ELEVATED, WITH GUSTY AND ERRATIC
WINDS THE MAIN HAZARD. ANY CLOUD TO GROUND LIGHTNING STRIKES
COULD ALSO PRODUCE NEW FIRE STARTS, AND MENTIONED THIS IN THE
FIRE WEATHER WATCH.
FOR FRIDAY, MINIMUM RELATIVE HUMIDITY WILL RANGE FROM 20 TO 30
PERCENT (LOWEST WEST AND NORTH CENTRAL), THOUGH WINDS WILL BE
RELATIVELY LIGHT FROM THE EAST/NORTHEAST.
INCREASING SOUTHERLY FLOW OVER THE WEEKEND WILL RESULT IN HIGH
TEMPERATURES WARMING INTO THE MID 80S TO LOWER 90S. A PERSISTENT
DRY BOUNDARY LAYER COUPLED WITH THESE TEMPERATURES WILL RESULT
IN DAYTIME MINIMUM HUMIDITY FORECAST FROM 15 TO 25 PERCENT BOTH
SATURDAY AND SUNDAY. THE DEGREE OF MIXING COULD SEE EVEN LOWER
RH VALUES SOME PLACES. EXPECTED GUSTY SOUTHERLY WINDS BOTH DAYS
WILL INCREASE THE POSSIBILITY OF NEAR-CRITICAL TO CRITICAL FIRE
CONDITIONS.
CONTINUED DRY AND BREEZY CONDITIONS WILL BE POSSIBLE ON MONDAY
ACROSS PORTIONS OF THE REGION.
BIS WATCHES/WARNINGS/ADVISORIES
FIRE WEATHER WATCH FROM THURSDAY AFTERNOON THROUGH THURSDAY
EVENING FOR NDZ001>005-009>013-017>021-033-034.
DISCUSSION...NH
AVIATION...NH
FIRE WEATHER...NH
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