Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 230826
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
326 AM CDT SAT AUG 23 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 326 AM CDT SAT AUG 23 2014

THE LATEST WATER VAPOR IMAGERY SHOWS A CLOSED/DEEP UPPER LOW
CIRCULATING OVER SOUTHWEST IDAHO. A COUPLE OF STRONG SHORTWAVE
TROUGHS EVIDENT WITH HIGH PRECIPITABLE WATER VALUES PER LARGE
PLUME OF MOISTURE ROTATING UP FROM KANSAS/NEBRASKA AND INTO SOUTH
DAKOTA EARLY THIS MORNING. THIS WILL RESULT IN A LONG DURATION OF
MODERATE TO HEAVY RAINSHOWERS AND SCATTERED THUNDERSTORMS ACROSS
WESTERN AND CENTRAL NORTH DAKOTA DURING THE SHORT TERM PERIOD.

MAIN FOCUS TODAY/TONIGHT WILL BE TWOFOLD...MONITORING THE HEAVY
RAINS AND POSSIBLE FLOODING ISSUES...AND POTENTIAL FOR SEVERE
THUNDERSTORMS IN FAR SOUTH CENTRAL NORTH DAKOTA AND ACROSS THE
JAMES RIVER VALLEY.

NO CHANGES TO THE ONGOING FLOOD WATCH. CATEGORICAL POPS CONTINUE
TODAY...INCREASING FROM SOUTH TO NORTH. THE LATEST SURFACE MAP
SHOWS PRESSURE FALLS MAXIMIZED IN SOUTHEAST MONTANA AND WESTERN
SOUTH DAKOTA. EXPECTING A SURFACE LOW PRESSURE CURRENTLY IN
EASTERN WYOMING TO DEEPEN AS IT MOVES NORTHEAST TOWARDS THIS
REGION. IN DOING SO...BRISK NORTHEAST TO EASTERLY BOUNDARY LAYER
WINDS WILL DEVELOP ACROSS WESTERN AND CENTRAL NORTH DAKOTA TODAY
WITH SUSTAINED WINDS OF 15KT TO 25KT...AND GUSTS TO AROUND 30KT.
THE SURFACE LOW WILL BE LOCATED NEAR BISMARCK BY 06Z SUNDAY...THUS
WINDS WILL ABATE SATURDAY EVENING...WITH THE HEAVIEST RAINS AND
STRONGEST WINDS SHIFTING INTO NORTHERN NORTH DAKOTA. OVERALL TREND
AFTER 06Z SUNDAY IS FOR POPS TO LOWER FROM SOUTH TO NORTH AS THE
SURFACE LOW SHIFTS INTO MINOT BY 12Z SUNDAY. HAVE BEEN SLOW TO
DECREASE POPS IN THE FAR WEST SATURDAY NIGHT WITH WRAP AROUND
MOISTURE REMAINING PERSISTENT.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 326 AM CDT SAT AUG 23 2014

A VERTICALLY STACKED LOW PRESSURE SYSTEM WILL CONTINUE TO LIFT
NORTH INTO CANADA THROUGH SUNDAY NIGHT. DRY SLOTTING IS PROGGED TO
DEVELOP ACROSS THE JAMES RIVER VALLEY...WITH WRAP AROUND MOISTURE
MAINTAINING CATEGORICAL TO LIKELY POPS ACROSS WESTERN NORTH DAKOTA
SUNDAY. THE CHANCES FOR HEAVY RAIN WILL ALSO DIMINISH THROUGH THE
DAY AS THE LOW LIFTS FARTHER NORTHEAST OUT OF THE AREA. NOT
EXPECTING MUCH IN THE WAY OF THUNDERSTORM ACTIVITY AS LAPSE RATES
ALOFT BECOME STABLE. MODELS PROG SHOWALTER INDICES BETWEEN +6 AND
+10 BY LATE SUNDAY...LEADING TO THE CONVECTIVE TYPE PRIMARILY
BEING RAIN SHOWERS. LINGERING WRAP AROUND MOISTURES IS EXPECTED TO
PRODUCE A SLIGHT CHANCE FOR RAIN SHOWERS NORTH ON MONDAY.

A POSITIVELY TILTED UPPER LEVEL TROUGH IS THEN PROGGED TO DEVELOP
OVER THE ROCKIES TUESDAY. SHORTWAVES AHEAD OF THE TROUGH AXIS
SHOULD GENERATE A CHANCE OF SHOWERS TUESDAY...MAINLY ALONG AND
SOUTH OF I-94. AS THE TROUGH AXIS PIVOTS ACROSS THE STATE TUESDAY
NIGHT...UPPER LEVEL RIDGING IS FORECAST TO BEGIN BUILDING INTO THE
REGION WEDNESDAY. THE UPPER RIDGE IS EXPECTED TO CONTINUE BUILDING
THROUGH FRIDAY...LEADING TO A WARMING/DRYING TREND THROUGH THE END
OF THE PERIOD.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 326 AM CDT SAT AUG 23 2014

EXPECT WIDESPREAD MODERATE TO HEAVY RAIN DURING THE TAF PERIOD
RESULTING IN LIFR CIGS AND IFR VSBYS...ESPECIALLY FROM 12Z
SATURDAY THROUGH 06Z SUNDAY. THE HEAVY RAIN WILL TAPER OFF ACROSS
THE SOUTHERN AERODROMES KDIK/KBIS/KJMS AFTER 00Z SUNDAY...BUT WILL
REMAIN OVER KISN/KMOT THROUGH AT LEAST 06Z SUNDAY.

&&

.HYDROLOGY...
ISSUED AT 326 AM CDT SAT AUG 23 2014

MODERATE TO HEAVY RAINS OVER THE PAST WEEK HAVE KEPT SOIL MOISTURE
ABNORMALLY HIGH ACROSS THE CWA. HEAVY RAINS EXPECTED TODAY INTO
TONIGHT ARE LIKELY TO OVERWHELM THE CURRENT INFILTRATION RATES OF
THE SOIL AND LEAD TO OVERLAND FLOODING AND CREATE A GREATER THAN
NORMAL RUNOFF. THIS ENHANCED RUNOFF RATES WILL ENCOUNTER ALREADY
WELL ABOVE NORMAL FLOW IN NEARLY EVERY SIGNIFICANT SMALL STREAM
AND RIVER IN THE AREA. WHILE THERE IS NO REASONABLE EXPECTATION OF
MAJOR RIVER FLOODING...AT A MINIMUM THERE WILL BE SIGNIFICANT
WITHIN BANK RISES...AND MINOR RIVER FLOODING CANNOT BE RULED OUT.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR NDZ017>020-031>034-
040>046-050.

FLOOD WATCH FROM 10 AM CDT THIS MORNING THROUGH SUNDAY AFTERNOON
FOR NDZ001>005-009>013-021>023-035-036-047.

&&

$$

SHORT TERM...KS
LONG TERM...TM
AVIATION...KS
HYDROLOGY...KS




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