Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 240245
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
945 PM CDT SAT MAY 23 2015

.UPDATE...
ISSUED AT 937 PM CDT SAT MAY 23 2015

INITIAL BAND OF SHOWERS LIFTING NORTH THROUGH SOUTHWEST AND SOUTH
CENTRAL NORTH DAKOTA...WITH NOTHING MORE THAN SPRINKLES. THE AREA
OF SHOWERS OVER THE SOUTHWEST HAS LIFTED INTO MORE STABLE AIR AND
HAS DISSIPATED RAPIDLY OVER THE PAST HOUR OR SO. DID PUSH SLIGHT
CHANCE POPS A LITTLE FARTHER NORTH OF THE INTERSTATE SOUTHWEST AND
SOUTH CENTRAL THIS EVENING TO ACCOUNT FOR THIS...OTHERWISE MAINLY
SLIGHT CHANCE POPS FOR THE REMAINDER OF THE EVENING AND INTO THE
EARLY OVERNIGHT HOURS SOUTH OF THE INTERSTATE...WITH DRY
CONDITIONS NORTH. ALSO HELD BACK ON THE LIKELY POPS COMING INTO
THE SOUTH ON SUNDAY...LIMITING THEM TO MAINLY ALONG THE SOUTH
DAKOTA BORDER IN THE MORNING AND BRINGING THEM NORTH TO AROUND THE
I-94 CORRIDOR AFTER 18Z.

UPDATE ISSUED AT 638 PM CDT SAT MAY 23 2015

A BAND OF SHOWERS IS LIFTING SLOWLY NORTHWARD THROUGH SOUTHWEST
NORTH DAKOTA. OTHERWISE NOTHING MORE THAN POSSIBLY A FEW SPRINKLES
OVER THE SOUTHWEST AND SOUTH CENTRAL ALONG AND SOUTH OF I-94.
LATEST MODELS CONTINUE THE TREND OF SLOWING THE ARRIVAL OF
PRECIPITATION TONIGHT AND HAVE ADJUSTED POPS DOWNWARD. DID
MENTION SOME HIGH POPS TO ACCOUNT FOR THE BAND LIFTING THROUGH THE
SOUTHWEST EARLY THIS EVENING. OTHERWISE MAINLY SLIGHT CHANCE POPS
THIS EVENING...THEN SOME CHANCE POPS MOVING INTO THE FAR SOUTH
AFTER MIDNIGHT. DID KEEP SOME LIKELY POPS FOR NOW ALONG THE SOUTH
DAKOTA BORDER AFTER 09Z. WILL MONITOR THOUGH THROUGH THE EVENING.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 237 PM CDT SAT MAY 23 2015

THE MAIN FOCUS FOR THE SHORT TERM IS TIMING AND AREAL COVERAGE
OF RAIN TONIGHT AND SUNDAY.

THE LATEST MODEL TRENDS INDICATE YET MORE DELAY IN TIMING OF THE
ONSET OF RAIN MOVING NORTHWARD FROM THE LARGE STORM SYSTEM CENTERED
OVER COLORADO.

THE GFS MODEL REMAINS THE MOST AGGRESSIVE IN BRINGING MEASURABLE
PRECIPITATION ACROSS THE STATE...ALREADY INDICATING THAT RAIN
SHOULD BE ADVANCING NORTH TOWARDS I-94. THIS MODEL WAS DISCOUNTED
FOR TODAY`S FORECAST. INSTEAD USED A BLEND OF THE NAM...ECMWF...HRRR
AND CANADIAN MODELS IN DETERMINING CLOUD AND PRECIPITATION ADVANCEMENT
NORTHWARD. LOW CLOUDS REMAINED STEADY BROKEN/OVERCAST AT HETTINGER
THIS AFTERNOON...WITH OVERCAST SKIES REACHING DICKINSON AND NEARLY
AT BISMARCK. RADAR RETURNS FROM THE BOWMAN RADAR HAVE BEEN
INCREASING WITH INTENSITY AND AREAL COVERAGE THROUGHOUT THE DAY.
NOTED THAT BISON SD RECEIVED 0.01 OF RAIN EARLY THIS
AFTERNOON...THUS PRECIPITATION IS NOW FINALLY REACHING THE GROUND.
EXPECT THAT THE BOWMAN AREA IS SEEING SOME SCATTERED LIGHT RAIN.

CURRENT THINKING IS THAT SHOWERS IN THE FAR SOUTHWEST SHOULD BECOME
MORE NUMEROUS DURING THE EVENING...AND THAT SCATTERED RAIN SHOULD
SPREAD NORTH AND EAST WITH TIME. THE MODELS WERE KEYING IN ON
THE UPPER LEVEL LOW REMAINING SOUTHWEST OF THE STATE TONIGHT...
MAINLY OVER THE FRONT RANGE OF COLORADO AND WYOMING...WITH MORE
OF THE ENERGY AND ASSOCIATED MOISTURE REMAINING FARTHER WEST OVER
THE SOUTHWEST PORTION OF NORTH DAKOTA. HELD OFF WITH HIGHER PRECIP
CHANCES OVER MUCH OF THE JAMES VALLEY UNTIL AROUND DAYBREAK SUNDAY.

ON SUNDAY THE SOUTH HALF OF THE STATE IS LIKELY TO SEE RAIN...WITH
INCREASING CHANCES FARTHER NORTH WITH TIME...BUT THE NORTHERN TIER OF
COUNTIES ALONG THE CANADIAN BORDER WILL HAVE LESS THAN 50 PERCENT
CHANCES OF RAIN. SURFACE AND BOUNDARY LAYER INSTABILITY INCREASES
THROUGH THE MORNING WITH BETTER FORCING AND CAPE. WILL HAVE A
SLIGHT CHANCE MENTION OF THUNDER SUNDAY MORNING...AND FOR THE CHANCE
OF SCATTERED THUNDERSTORMS IN NUMEROUS RAIN SHOWERS SOUTH IN
THE AFTERNOON.

EXPECTING ONLY A TENTH OR TWO TENTHS OF AN INCH OF RAIN TONIGHT SOUTHWEST.
EXPECTING 0.25 TO 0.50 SOUTHWEST ON SUNDAY WITH 0.20 TO 0.40 OVER THE
REST OF SOUTH CENTRAL NORTH DAKOTA SUNDAY. LESSER AMOUNTS FARTHER NORTH.

LOWS TONIGHT FROM 45 TO 50 MOST AREAS IN CLOUD COVER. HIGHS SUNDAY
FROM THE UPPER 50S TO MID 60S SOUTH...AND UPPER 60S TO 70 NORTH.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 237 PM CDT SAT MAY 23 2015

UNSETTLED WEATHER FOR MUCH OF THE LONG TERM PERIOD. RELIED MORE ON
THE ECMWF VERSUS THE GFS BEFORE THE SUPERBLEND TOOK OVER TUESDAY
AFTERNOON THROUGH SATURDAY. THE GFS HAS BEEN CONSISTENTLY OVER-
FORECASTING AREAL COVERAGE OF RAINFALL AND ASSOCIATED AMOUNTS. PER
ECMWF...A NEARLY VERTICALLY STACKED SYSTEM FROM THE SHORT TERM
PERIOD WILL GRADUALLY LIFT FROM SOUTHEAST WYOMING SUNDAY NIGHT TO
EASTERN MINNESOTA BY MONDAY AFTERNOON. LIKELY SHOWERS AND A SLIGHT
CHANCE FOR THUNDERSTORMS DURING THIS TIME...FAVORING CENTRAL AND
SOUTHERN NORTH DAKOTA...WITH LESSER CHANCES IN THE NORTH. FOR MONDAY
NIGHT THROUGH SATURDAY...A PROGRESSIVE PATTERN WITH A MID LEVEL
SHORTWAVE ALMOST ON A DAILY BASIS. THE DAYS WITH THE LOWEST
PROBABILITIES FOR PRECIPITATION AND HENCE MOSTLY A DRY FORECAST
RESIDE IN THE MONDAY NIGHT THROUGH TUESDAY NIGHT PERIOD...AND  ON
SATURDAY. WEDNESDAY THROUGH FRIDAY FAVOR HIGHER CHANCES FOR SHOWERS
AND POSSIBLE THUNDERSHOWERS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 937 PM CDT SAT MAY 23 2015

VFR CONDITIONS TO BEGIN THE 00Z TAF PERIOD. SURFACE AND UPPER
LEVEL LOW PRESSURE OVER THE SOUTHERN AND CENTRAL ROCKIES WILL MOVE
SLOWLY NORTHWARD TONIGHT AND SUNDAY...BRINGING INCREASING
PRECIPITATION CHANCES TO THE SOUTHERN TAF SITES BY SUNDAY. EXPECT
MAINLY SCATTERED PRECIPITATION SUNDAY MORNING WITH MORE
WIDESPREAD PRECIPITATION MOVING IN SUNDAY AFTERNOON. BROUGHT MVFR
CEILINGS INTO KDIK AROUND 12Z...KBIS AROUND 16Z AND KJMS AROUND
21Z. KEPT THE NORTHERN TAF SITES VFR THROUGH THE PERIOD. SOME
HINTS AT LIFR CONDITIONS AT KDIK BEGINNING 08-12Z. WILL HOLD OFF
ON THE LIFR FOR NOW AND WILL CONTINUE TO MONITOR.

&&

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

$$

UPDATE...TWH
SHORT TERM...JV
LONG TERM...KS
AVIATION...TWH



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