Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 290233
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
933 PM CDT THU APR 28 2016

.UPDATE...
ISSUED AT 929 PM CDT THU APR 28 2016

ONLY SMALL TWEAKS WERE NEEDED FOR THIS UPDATE. LOWERED THE MINIMUM
TEMPERATURES SLIGHTLY BECAUSE OF DRY AIR IN PLACE ACROSS MOST OF
WESTERN AND CENTRAL NORTH DAKOTA. ALSO INTRODUCED SOME PATCHY FOG
IN THE SOUTHWEST...AS SNOW FROM THE PAST COUPLE OF DAYS HAS
MELTED...LEAVING A THIN LAYER OF MOISTURE NEAR THE SURFACE.
OTHERWISE...THE FORECAST LOOKS ON TRACK.

UPDATE ISSUED AT 632 PM CDT THU APR 28 2016

NO MAJOR CHANGES WERE NEEDED WITH THIS UPDATE. JUST BLENDED THE
LATEST OBSERVATIONS WITH THE CURRENT FORECAST.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 257 PM CDT THU APR 28 2016

IT WILL BE QUIET AND DRY THROUGH FRIDAY AND BEYOND.

AS OF 1950 UTC...A SURFACE RIDGE AXIS IS BUILDING SOUTHWARD OUT OF
CANADA AND INTO NORTHERN ND. THE RIDGE IS FORECAST TO REMAIN WELL
OFF TO THE NORTHEAST OF THE AREA THROUGH FRIDAY...BUT DRY EAST OR
NORTHEAST LOW-LEVEL FLOW WILL PREVAIL ON ITS SOUTHERN FLANK OVER
ND THROUGH THIS TIME. OVERALL THERMAL FIELDS WILL CHANGE LITTLE.
THAT MEANS THAT THE PRIMARY DRIVER OF TEMPERATURES WILL BE LOW-
LEVEL MOISTURE CONTENT AND CLOUD COVER...THE LATTER OF WHICH WILL
ALSO BE PARTLY CONTROLLED BY NEAR-GROUND HUMIDITIES. THE OBSERVED
SURFACE DEWPOINTS THIS AFTERNOON RANGE FROM 10 TO 15 F IN NORTHERN
ND TO THE 20S F IN MN...WHERE DEEP-LAYER SUBSIDENCE IS LESS SINCE
THAT AREA IS FURTHER AWAY FROM THE CENTER OF THE RIDGE IN CANADA.
WE EXPECT DEWPOINTS TO RECOVER ONCE THE BOUNDARY LAYER DECOUPLES
THIS EVENING...BUT THEIR INITIALLY-LOW STATE MADE US LEAN TOWARD
COOLER MOS-BASED TEMPERATURE GUIDANCE FOR LOWS TONIGHT...MAINLY IN
NORTHERN AREAS.

ON FRIDAY...HIGHS ARE FORECAST TO RANGE FROM THE LOWER 50S F OVER
SOUTHWEST ND TO AROUND 60 F IN NORTH CENTRAL ND...WHERE WE EXPECT
CLOUD COVER AND BOUNDARY LAYER HUMIDITIES TO ONCE AGAIN BE LOWEST
BASED ON TRENDS TODAY AN AN EXPECTATION FOR VERY LITTLE CHANGE IN
THE SYNOPTIC-SCALE PATTERN. DEWPOINTS MAY NOT FALL AS LOW AS THEY
DID TODAY THOUGH SINCE THE AIR MASS TRAJECTORY WILL BE OUT OF MN
/WHERE LOW-LEVEL MOISTURE IS A BIT HIGHER/.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 257 PM CDT THU APR 28 2016

WARM...DRY AND LOW-IMPACT WEATHER IS EXPECTED THIS WEEKEND AND ALL
THE WAY THROUGH NEXT WEEK AS MEAN 500-MB RIDGING TAKES CONTROL.

THE 00 AND 12 UTC GFS AND ECMWF ARE RATHER AGREEABLE ON THE BROAD
PICTURE WHICH HAS CONSISTENTLY CALLED FOR A SLOW BREAKDOWN OF THE
WESTERN UNITED STATES TROUGH AND REPLACEMENT BY RIDGING ALOFT FOR
A MULTI-DAY PERIOD. MOREOVER...RIDGING ALOFT INITIALLY CENTERED ON
SOUTHERN CANADA IS FORECAST TO HOLD THE WEEKEND SHORTWAVE TROUGH
TO THE SOUTH OF ND...SO WE HAVE CONTINUED WITH A DRY FORECAST FOR
SATURDAY AND SUNDAY. IN FACT...THAT DRY FORECAST CONTINUES THROUGH
NEXT WEEK GIVEN RIDGING ALOFT. THAT IS SUPPORTED BY MAINLY DRY GFS
AND ECMWF DETERMINISTIC RUNS...AND GFS-ENSEMBLE-BASED CIPS ANALOGS
THAT ABOUT A 70 PERCENT PROBABILITY OF BELOW-NORMAL PRECIPITATION.
OUR FORECAST HIGHS WERE BASED ON THE 12 UTC MULTI-MODEL CONSENSUS
AND THAT CALLS FOR TEMPERATURES NEAR 60 F SATURDAY AND SUNDAY AND
DEEP INTO THE 60S IF NOT 70S F MONDAY THROUGH THURSDAY. ONE ITEM
OF INTEREST WILL BE HOW RECENT RAINS AND RESULTANT SOIL MOISTURE
AND VEGETATIVE GROWTH/GREEN-UP IMPACT THE MAGNITUDE OF WARMING...
AS BOTH COULD RESULT IN HIGHS BEING A BIT LOWER THAN EXPECTED.

ONE OTHER POTENTIALLY LOWER-PREDICTABILITY FEATURE NEXT WILL WILL
BE HOW FAR EAST THE 500-MB RIDGE AXIS OVER THE ROCKIES EXTENDS AND
WHETHER ANY BACKDOOR COOL FRONTS IMPACT THE REGION. THE LATTER IS
RELATED TO POTENTIAL SHORTWAVE TROUGHS IN NORTHWEST FLOW CUTTING
ACROSS THE HUDSON BAY AREA...AS SUGGESTED BY THE 06 AND 12 UTC GFS
RUNS...BUT LESS-SO BY CORRESPONDING ECMWF SIMULATIONS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 632 PM CDT THU APR 28 2016

VFR CEILINGS AND VISIBILITIES WILL PREVAIL THROUGH THE FORECAST
PERIOD. WINDS WILL GENERALLY REMAIN LIGHT OUT OF THE EAST OR
NORTHEAST.


&&

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

$$

UPDATE...ZH
SHORT TERM...CJS
LONG TERM...CJS
AVIATION...ZH


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