Area Forecast Discussion
Issued by NWS Bismarck, ND

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398
FXUS63 KBIS 052251
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
551 PM CDT THU MAY 5 2016

.UPDATE...
ISSUED AT 551 PM CDT THU MAY 5 2016

WE HAVE ADDED A SLIGHT CHANCE OF A SHOWER OR THUNDERSTORM TO THE
FORECAST THROUGH MID EVENING IN NORTHWEST ND. A HIGH-BASED SHOWER
DEVELOPED NORTHWEST OF WILLISTON NEAR 2230 UTC...AND EVEN THOUGH
THE ENTLN TOTAL LIGHTNING PLOT HAS NOT YET SHOWN ANY IN-CLOUD OR
CLOUD-TO-GROUND STRIKES...THE STEEP LAPSE RATES AND WEAK MLCAPE
/UP TO 250 J/KG PER THE SPC MESOANALYSIS/ IN THAT AREA SUGGEST A
RUMBLE OR TWO OF THUNDER IS POSSIBLE. VISIBLE SATELLITE IMAGERY
THROUGH 2245 UTC SHOWS CUMULUS ALL ALONG A WEAK SURFACE PRESSURE
TROUGH EXTENDING FROM SOUTHEAST SASKATCHEWAN INTO EASTERN MT SO IT
IS PLAUSIBLE MORE THAN JUST THAT INITIAL SHOWER MAY FORM. THAT
BEING SAID...RECENT HRRR RUNS ARE LIKELY OVERDONE WITH EXPECTED
DEVELOPMENT BASED ON THAT MODEL/S RECENT AND LONGER-TERM BIASES.

OTHERWISE...WE ARE CONTINUING THE RED FLAG WARNING IN EAST CENTRAL
ND FOR NOW GIVEN LATE-AFTERNOON OBSERVATIONS AND ONGOING FIRES.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 235 PM CDT THU MAY 5 2016

THE MAIN IMPACTS IN THE SHORT TERM ARE CRITICAL FIRE CONDITIONS
TODAY AND A COLD FRONT TOMORROW.

AN UPPER LEVEL RIDGE...COMBINED WITH A SURFACE TROUGH AND
SOUTHWESTERLY MIXING WINDS...HAVE ALLOWED TEMPERATURES THIS
AFTERNOON TO RISE RAPIDLY INTO THE 80S AND LOW 90S. THESE WARM
TEMPERATURES HAVE FURTHER EXACERBATED DRY BOUNDARY LAYER
CONDITIONS. WITH VERY DRY AIR MIXING DOWN RELATIVE HUMIDITY VALUES
HAVE PLUMMETED INTO THE TEENS AND LOW 20S. WIND SPEEDS HAVE BEEN A
BIT BREEZY ACROSS THE JAMES VALLEY. THIS IS WHAT PROMPTED THE
ISSUANCE OF THE RED FLAG WARNING. WIND SPEEDS AROUND 20
MPH...COMBINED WITH HUMIDITY 20 PERCENT OR LESS AND DRY FUELS IS
PRODUCING CRITICAL FIRE CONDITIONS ACROSS THE JAMES VALLEY.

A COLD FRONT WILL SWEEP THROUGH TONIGHT INTO FRIDAY MORNING. WINDS
WILL SHIFT OUT OF THE NORTH BETWEEN 20 AND 30 MPH. TOMORROW
AFTERNOON MINIMUM RELATIVE HUMIDITY AROUND 20 PERCENT IS EXPECTED
IN NORTHWEST AND PORTIONS OF NORTH CENTRAL NORTH DAKOTA BY LATE
AFTERNOON. HOWEVER...BY THIS TIME THE STRONGEST WINDS SHOULD HAVE
PASSED TO THE SOUTH. THEREFORE...THESE AREAS MAY ESCAPE CRITICAL
FIRE CONDITIONS. MODELS CONTINUE TO INDICATE A MAINLY DRY FRONTAL
PASSAGE...WITH A FEW ISOLATED SHOWERS POSSIBLE. HOWEVER...WITH A
PERSISTANT DRY BOUNDARY LAYER...THE LIKELIHOOD OF ANY
PRECIPITATION ACTUALLY REACHING THE GROUND IS RATHER MINIMAL.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 235 PM CDT THU MAY 5 2016

COOLER AIR WILL SETTLE INTO THE AREA THIS WEEKEND IN THE WAKE OF
FRIDAYS COLD FRONT. HOWEVER... PLEASANT TEMPERATURES ARE STILL
EXPECTED WITH HIGHS MAINLY IN THE 70S. DRY CONDITIONS WILL REMAIN.

CHANGES APPEAR ON THE HORIZON FOR THE START THE WORK WEEK AS
AN UPPER LOW CURRENTLY OFF THE CALIFORNIA COAST DEEPENS OVER THE
FOUR CORNERS REGION THIS WEEKEND AND LIFTS INTO THE PLAINS ON
MONDAY...BRINGING CHANCES FOR RAIN AND THUNDERSTORMS.

CHANCES FOR RAIN AND THUNDERSTORMS WILL LINGER OVER THE AREA
THROUGH THE WEEK AS THE GFS AND ECMWF HAVE THE LOW REMAINING
NEARBY THROUGH FRIDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 551 PM CDT THU MAY 5 2016

VFR CONDITIONS WILL CONTINUE TONIGHT AND FRIDAY. ISOLATED SHOWERS
OR THUNDERSTORMS ARE POSSIBLE IN NORTHWEST ND THIS EVENING. THE
MAIN AVIATION WEATHER ISSUE WILL BE A COLD FRONTAL PASSAGE LATE
TONIGHT AND FRIDAY MORNING...WHICH WILL SHIFT WINDS TO THE NORTH.
NORTHERLY WIND GUSTS TO AROUND 30 KT WILL OCCUR FRIDAY ACROSS ALL
OF WESTERN AND CENTRAL ND.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 8 PM CDT THIS EVENING FOR NDZ005-013-023-
025-037-048-051.

&&

$$

UPDATE...CJS
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...CJS



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