Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 261927
AFDBIS

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

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 119 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
INSTABLITY 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 119 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 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 119 PM CDT WED AUG 26 2015

VFR CONDITIONS ARE EXPECTED FOR THE 18Z TAF PERIOD. THERE WILL BE
MAINLY AN INCREASE IN MID AND HIGH LEVEL CLOUDS. AN ISOLATED
SHOWER OR THUNDERSTORM IS POSSIBLE TONIGHT INTO
THURSDAY...ESPECIALLY FOR THE SOUTHERN AERODROMES...BUT THOSE
CHANCES APPEAR TOO SMALL TO INTRODUCE INTO THE TAF. WINDS WILL
GENERALLY STAY LESS THAN 10 KTS THROUGH THE PERIOD.

&&

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

$$

SHORT TERM...CK
LONG TERM...ZH
AVIATION...CK



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