Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 270246
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
946 PM CDT WED AUG 26 2015

.UPDATE...
ISSUED AT 945 PM CDT WED AUG 26 2015

WATER VAPOR IMAGERY NEATLY SHOWS THE WRAPPED UP SYSTEM OFF THE
PACIFIC NORTHWEST / BRITISH COLUMBIA COAST.

CLOSER TO HOME...WEAK RETURNS ON RADAR PRODUCED NOTHING MORE THAN
SPRINKLES AND SO EARLIER WE DROPPED POPS FOR THE EVENING. SHOWERS
AND STORMS WERE FIRING FROM NORTHEAST WYOMING TO THE NORTHERN
BLACK HILLS...AND JUST SOUTHWEST OF THE HILLS. MOVEMENT WAS EAST-
NORTHEAST. AT THIS RATE IF THEY HELD TOGETHER IT WOULD BE A LONG
TIME GETTING TO NORTH DAKOTA. HIGH RESOLUTION SHORT TERM MODELS
DIFFER ON WHETHER OR NOT ACTIVITY WILL CROSS INTO NORTH DAKOTA.
NAM12 BRINGS IT IN BUT NOT UNTIL AFTER 4 AM AND JUST THE FAR
SOUTHWEST...RAP13 SAYS IT WILL NOT MAKE IT...HRRR ALSO SAYS NO GO.

WILL FURTHER DELAY POPS AND PUSH THEM BACK FARTHER TOWARD THE
SOUTHWEST / SOUTH DAKOTA BORDER THROUGH DAYBREAK.

HAZE DID REDUCE VISIBILITY AT WILLISTON TO 5 MILES FOR AN HOUR OR
SO EARLIER...NOW BACK TO 10 MILES.

UPDATE ISSUED AT 645 PM CDT WED AUG 26 2015

RADAR RETURNS MOVED OVER BISMARCK AND NOTHING MORE THAN MID LEVEL
CLOUDS WERE OBSERVED. SOME OF THE HIGHER RETURNS COULD BE
PRODUCING A SPRINKLE OF RAIN AT MOST...FROM WILLISTON THROUGH
HARVEY AND CARRINGTON...AND SOUTHEAST OF BISMARCK. WITH THAT
BEING THE MOST INTENSE RAIN HAVE OPTED TO DROP POPS FOR THE REST
OF THE DAYLIGHT HOURS AND INTO THE EVENING.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 227 PM CDT WED AUG 26 2015

THE MAIN CONCERN IN THE SHORT TERM PERIOD WILL BE THE CHANCE OF
THUNDERSTORMS. UPPER AIR ANALYSIS PLACED A LARGE H5 RIDGE ACROSS
THE CENTRAL AND SOUTHWEST UNITED STATES WITH A TROUGH OFF THE
NORTHWEST COAST AND ANOTHER IN THE EASTERN CONUS.

FOR THE REMAINDER OF THIS AFTERNOON...REGIONAL RADAR MOSAIC
SHOW TWO BANDS OF LIGHT RETURNS. ONE IN THE NORTHWEST PART OF THE
STATE...AND ONE SOUTHWEST. LOW LEVEL DRY AIR SHOULD LIMIT THE
OVERALL RAIN POTENTIAL THIS AFTERNOON...THOUGH HAVE SEEN A FEW
RETURNS APPROACH 40 DBZ IN THE NORTH. FOR THAT REASON...HAVE
ADDED A SLIGHT CHANCE OF SHOWERS IN THE NORTHWEST AND NORTH
CENTRAL THROUGH 00Z.

FOR TONIGHT INTO THURSDAY...THE SHORT TERM MODELS ARE IN GENERAL
AGREEMENT THAT A H5 WAVE WILL PIVOT AROUND THE RIDGE AND MOVE
ACROSS WYOMING INTO SOUTH DAKOTA. THE BEST UPPER FORCING WITH THIS
FEATURE WILL BE ACROSS SOUTH DAKOTA...WITH SHORT TERM MODELS
GENERALLY KEEPING ANY CHANCE OF SHOWERS / THUNDERSTORMS SOUTH OF
I-94. THE OUTLIER TO THIS HAS BEEN THE ECMWF...AND FOR NOW WILL
FOLLOW CLOSER TO THE CONSENSUS WITH ONLY SLIGHT CHANCE POPS
SPILLING NORTH OF I-94.

WILL CONTINUE TO CARRY SHOWERS AND THUNDERSTORMS WITH ENOUGH
INSTABILITY FORECAST TO WARRANT THE THUNDERSTORM CHANCES. IN
REGARDS TO SEVERE WEATHER...THE LATEST DAY 2 OUTLOOK FROM THE
STORM PREDICTION CENTER KEEPS THE MARGINAL RISK WELL SOUTH OF
NORTH DAKOTA...SO WILL STAY THE COURSE AND NOT MENTION ANY SEVERE
THUNDERSTORM POTENTIAL IN THE UPDATED HAZARDOUS WEATHER OUTLOOK.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 227 PM CDT WED AUG 26 2015

MILD TEMPERATURES AND ISOLATED THUNDERSTORM CHANCES HIGHLIGHT THE
EXTENDED RANGE.

AT THE START OF THE PERIOD...A FLATTENING UPPER LEVEL
RIDGE...LOCATED JUST TO THE WEST OF THE COUNTY WARNING AREA...WILL
BEGIN TO TRANSITION THE PATTERN TO QUASI-ZONAL FLOW. AS SURFACE LOW
PRESSURE CONTINUES TO DEVELOP NEAR THE SOUTH DAKOTA NEBRASKA
BORDER...EXPECT A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS IN
SOUTH CENTRAL AND SOUTHEAST NORTH DAKOTA THURSDAY NIGHT AND INTO
FRIDAY MORNING...MAINLY SOUTH OF INTERSTATE 94. THE 12Z NAM AND GFS
MODEL RUNS ALSO HINT AT BRINGING ANOTHER IMPULSE INTO NORTHWEST AND
NORTH CENTRAL NORTH DAKOTA BY LATE THURSDAY NIGHT AND INTO FRIDAY
MORNING...WHICH MAY SPARK AN ISOLATED SHOWER OR THUNDERSTORM. MOST
MODELS ARE PAINTING A PICTURE OF MODEST CAPE AND WEAK SHEAR...THUS
THUNDER CONFIDENCE IS NOT HIGH.

BY FRIDAY AFTERNOON...THE UPPER LEVEL RIDGE WILL BEGIN TO MOVE EAST
AND AMPLIFY...WHILE THE AXIS WILL BE LOCATED DIRECTLY OVER THE
FORECAST AREA BY SATURDAY EVENING. FRIDAY AND SATURDAY SHOULD
FEATURE VERY WARM TEMPERATURES WITH MOSTLY DRY CONDITIONS. HIGHS
WILL CLIMB INTO THE 90S ON BOTH DAYS...WITH MID TO UPPER 90S
POSSIBLE IN THE WEST ON SATURDAY.

A WEAK COLD FRONT AND UPPER LEVEL SHORTWAVE TROUGH WILL APPROACH THE
REGION ON SUNDAY. ISOLATED SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE ALONG THIS BOUNDARY BY SUNDAY NIGHT AND INTO MONDAY
MORNING...BUT VERY WARM TEMPERATURES ALOFT MAY WORK TO CAP
CONVECTION. WE WILL REMAIN IN AN UPPER LEVEL SOUTHWEST FLOW REGIME
THROUGH THE FIRST HALF OF THE WEEK...GIVING US DAILY CHANCES FOR
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS THROUGH WEDNESDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 945 PM CDT WED AUG 26 2015

VFR THROUGH THE TAF VALID PERIOD. AN ISOLATED SHOWER OR
THUNDERSTORM IS POSSIBLE AFTER 09Z ACROSS SOUTHWEST INTO SOUTH
CENTRAL NORTH DAKOTA. THE CHANCES WERE SO SMALL THAT NO MENTION
WAS INCLUDED IN THE KDIK NOR KBIS TAF. SMOKE FROM WESTERN FIRES
HAD SPREAD OVER THE REGION. THE SMOKE WAS AT HIGH LEVELS AND THE
MOST LIKELY PLACE FOR IT TO REDUCE SURFACE VISIBILITY WOULD BE AT
KISN...POSSIBLY TO 6SM FROM TIME TO TIME.

&&

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

$$

UPDATE...JPM
SHORT TERM...CK
LONG TERM...ZH
AVIATION...JPM


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