Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 230528
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1228 AM CDT THU APR 23 2015

.UPDATE...
ISSUED AT 1221 AM CDT THU APR 23 2015

PREVIOUS FORECAST IS ON TRACK.

UPDATE ISSUED AT 927 PM CDT WED APR 22 2015

CLEAR SKIES AND LIGHT WINDS TONIGHT. CURRENT FORECAST LOOKS GOOD.

UPDATE ISSUED AT 624 PM CDT WED APR 22 2015

SURFACE HIGH PRESSURE OVER EASTERN NORTH DAKOTA WILL MOVE EAST
TONIGHT. LOW PRESSURE TROUGH IN MONTANA WILL MOVE TO THE WESTERN
DAKOTAS THURSDAY. SURFACE WINDS WILL INCREASINGLY BECOME SOUTHEAST
AND BRING A CHANCE OF LIGHT SHOWERS TO WESTERN NORTH DAKOTA THURSDAY
AFTERNOON. CURRENT FORECAST TRENDING WELL WITH NO SIGNIFICANT
UPDATES.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 322 PM CDT WED APR 22 2015

BORDERLINE FIRE WEATHER CONCERNS AND SCATTERED RAIN SHOWERS
THURSDAY HIGHLIGHT THE SHORT TERM.

SURFACE HIGH PRESSURE ACROSS EASTERN NORTH AND SOUTH DAKOTA TODAY
IS FORECAST TO PROPAGATE INTO THE UPPER MISSISSIPPI VALLEY ON
THURSDAY...WITH A DEEPENING LEE SURFACE TROUGH ACROSS EASTERN
MONTANA AND WYOMING. THUS...RETURN FLOW IS EXPECTED TO INCREASE
THROUGH THE DAY ON THURSDAY. SEE THE FIRE WEATHER DISCUSSION BELOW
FOR BORDERLINE FIRE WEATHER CONCERNS SOUTHWEST.
OTHERWISE...SCATTERED RAIN SHOWERS ARE FORECAST THURSDAY AFTERNOON
WITH A SHORTWAVE PROPAGATING ALONG THE INTERNATIONAL BORDER. GIVEN
STABILITY IN THE MID LEVELS...THUNDERSTORMS ARE NOT EXPECTED.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 322 PM CDT WED APR 22 2015

A MID LEVEL SHORTWAVE WILL WORK THROUGH WESTERN AND CENTRAL NORTH
DAKOTA THURSDAY NIGHT. THE NAM80 AND GFS40 BOTH ADVERTISING
SHOWALTER INDICES OF AROUND ZERO CELSIUS OR LESS WITH WEAK
CAPE/SHEAR. THE GFS IS MORE AGGRESSIVE WITH THIS IDEA THAN THE
NAM...WITH INSTABILITY PARAMETERS IN CLOSE PROXIMITY OF A CLOSED
700MB LOW AND SURFACE INVERTED TROUGH SCOOTING THROUGH
CENTRAL/NORTHERN SOUTH DAKOTA AND EXTENDING INTO FAR SOUTHERN
NORTH DAKOTA THURSDAY NIGHT. A BRIEF PERIOD OF 850MB SOUTHERLY
WINDS OF AROUND 25KT COULD RESULT IN ENOUGH MOISTURE ADVECTION FOR
A SLIGHT CHANCE OF ELEVATED NON-SEVERE THUNDERSTORMS IN THE FAR
SOUTHWEST AND FAR SOUTH CENTRAL THURSDAY EVENING. OTHERWISE A
CHANCE OF RAIN SHOWERS AND SNOW SHOWERS THURSDAY NIGHT...WITH A
CHANCE OF RAIN SHOWERS LINGERING OVER THE JAMES RIVER VALLEY
FRIDAY AS SHORTWAVE ENERGY CONTINUES TO SHIFT THROUGH THAT AREA.
FOR THE WEEKEND...A CLOSED UPPER LOW WILL MOVE FROM THE PACIFIC
NORTHWEST FRIDAY INTO THE SOUTHWEST/FOUR CORNERS AREA BY SUNDAY.
BOTH THE GFS AND ECMWF ARE IN GOOD AGREEMENT WITH A WET PERIOD
DEVELOPING IN THE WEST SUNDAY...THEN SPREADING INTO CENTRAL NORTH
DAKOTA SUNDAY NIGHT THROUGH MONDAY NIGHT. THE GFS KEEPS NORTH
DAKOTA DOMINATED MORE BY THE SOUTHERN STREAM UPPER LOW.
FURTHERMORE THE GFS DEVELOPS A CLOSED 700MB LOW ACROSS WESTERN AND
NORTHERN NORTH DAKOTA SUNDAY INTO MONDAY...WHICH COINCIDENTALLY
PRODUCES MORE WIDESPREAD AND HEAVIER PRECIPITATION AMOUNTS THAN
THE ECMWF. THE ECMWF IS LESS ROBUST WITH THE DURATION OF THE
SOUTHERN STREAM MOISTURE AND IS MORE PROGRESSIVE WITH A NORTHERN
STREAM SHORTWAVE SLIDING THROUGH LATE SUNDAY INTO MONDAY. EITHER
WAY IT APPEARS TO BE A WET PERIOD SUNDAY THROUGH MONDAY NIGHT. A
DRIER NORTHWEST FLOW DEVELOPS TUESDAY AND WEDNESDAY AS AN
ADVANCING UPPER RIDGE MOVES FROM THE NORTHERN ROCKIES INTO NORTH
DAKOTA BY WEDNESDAY NIGHT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1221 AM CDT THU APR 23 2015

VFR CONDITIONS ARE ANTICIPATED AT ALL TERMINALS THROUGH THE 06Z
TAF CYCLE. HIGH PRESSURE WILL CONTINUE TO PUSH EAST WITH LOW
PRESSURE OUT OF WYOMING MOVING INTO THE REGION. SOUTHEAST WINDS
WILL INCREASE THURSDAY AND CHANCES FOR SCATTERED RAIN SHOWERS WILL
INCREASE FROM WEST TO EAST THROUGH THE AFTERNOON AND NIGHT.

&&

.FIRE WEATHER...
ISSUED AT 322 PM CDT WED APR 22 2015

FOR THURSDAY ACROSS WESTERN AND CENTRAL NORTH DAKOTA...RELATIVE
HUMIDITY VALUES ARE EXPECTED TO RANGE FROM 15 TO 20 PERCENT
CENTRAL TO 20 TO 30 PERCENT WEST. SOUTHEAST WINDS WILL BE
STRONGEST ACROSS THE SOUTHWEST AT 15 TO 25 MPH. HOWEVER...THE
SLIGHTLY HIGHER RELATIVE HUMIDITY LEVELS SOUTHWEST WILL HELP TO
LIMIT FIRE WEATHER CONDITIONS FROM BECOMING CRITICAL. SCATTERED
SHOWERS ARE ALSO EXPECTED ACROSS THE WEST THURSDAY
AFTERNOON...SPREADING EAST INTO THE EVENING. LOOKING AHEAD...GREATER
MOISTURE IS EXPECTED TO MOVE INTO THE AREA...WITH MULTIPLE CHANCES
FOR LIGHT RAIN FRIDAY NIGHT THROUGH MONDAY.

&&

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

$$

UPDATE...MM
SHORT TERM...AYD
LONG TERM...KS
AVIATION...MM
FIRE WEATHER...AYD






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