Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 221137
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
637 AM CDT TUE APR 22 2014

.UPDATE...
ISSUED AT 636 AM CDT TUE APR 22 2014

MADE SOME SLIGHT MODIFICATIONS TO LOWER SKY COVER A BIT THIS
MORNING. OTHERWISE NO CHANGES WARRANTED OTHER THAN UPDATING THE
LATEST SENSIBLE WEATHER GRIDS.

&&

.SHORT TERM...(TODAY AND TONIGHT)

ISSUED AT 446 AM CDT TUE APR 22 2014

FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE WINDY
CONDITIONS DEVELOPING WEST TO EAST TODAY AND TONIGHT...INCREASING
CHANCES FOR RAIN TONIGHT...AND A SLIGHT CHANCE OF THUNDERSTORMS
WEST AND SOUTH CENTRAL TONIGHT.

CURRENTLY...UPPER LEVEL RIDGE AXIS OVER THE HIGH PLAINS CONTINUES
EAST. UPPER LEVEL TROUGH NEARING THE WEST COAST...WITH A CLOSED
UPPER LOW OFF THE BRITISH COLUMBIA COAST. SURFACE HIGH PRESSURE
OVER THE EASTERN DAKOTAS WITH INCREASING RETURN FLOW WEST.
TEMPERATURES ACROSS MY CENTRAL AND EAST PLUMMETED THE PAST SEVERAL
HOURS WITH A CLEAR SKY AND LIGHT WINDS. WARMER WEST WHERE UPPER
LEVEL CLOUDS ARE INCREASING AND A SOUTHEAST WIND IS HELPING TO
MIX UP THE LOW LEVEL ATMOSPHERE.

AS THE UPPER TROUGH MOVES INLAND TODAY OVER THE WESTERN
CONUS...LEE SIDE CYCLOGENESIS RAMPS UP WITH SURFACE LOW PRESSURE
DEEPENING ACROSS CENTRAL MONTANA. THIS WILL RESULT IN RETURN FLOW
INCREASING AND THE PRESSURE GRADIENT TIGHTENING THROUGHOUT THE
MORNING AND AFTERNOON ACROSS WESTERN AND CENTRAL NORTH DAKOTA.
BUFFER SOUNDINGS INDICATING SUSTAINED WINDS 20-24KTS WEST BY
18Z...WITH THESE SUSTAINED WINDS SPREADING EAST INTO MY CENTRAL
COUNTIES DURING THE AFTERNOON. NOT MUCH WIND GUST POTENTIAL
THROUGH MID-AFTERNOON WITH WIND MAGNITUDES BELOW 30KTS THROUGH THE
MIXED LAYER. THIS CHANGES LATER IN THE AFTERNOON AND DURING THE
EARLY EVENING HOURS WHEN A LOW LEVEL JET STARTS TO RAMP UP. MAY
SEE A FEW STRONGER LATE AFTERNOON WIND GUSTS TO 35KTS ACROSS THE
WEST...HOWEVER BY THIS TIME THE NIGHTTIME INVERSION WILL BE IN
DEVELOPMENT CUTTING OFF THE STRENGTHENING WINDS ALOFT AS THE TOP
OF THE MIXED LAYER GOES FROM 800MB TO JUST OFF THE SFC 23Z-01Z.
WINDS CONTINUE TO HOWL THROUGH THE NIGHT AS THE PRESSURE GRADIENT
REMAINS TIGHT. AT THIS TIME FORECAST WINDS DO NOT QUALIFY FOR A
WIND ADVISORY BUT SHOULD BE MONITORED.

UPPER RIDGE AXIS MOVES INTO THE EASTERN DAKOTAS TONIGHT
TRANSITIONING FLOW ALOFT TO SOUTHWESTERLY ALLOWING LEAD S/WV
IMPULSES TO LIFT TOWARDS AND THROUGH THE REGION. COUPLED WITH THE
50-60KT LOW LEVEL JET HELPING TO TRANSPORT/INCREASE PWATS TO
0.75"-1.00" FROM EARLIER VALUES AROUND 0.25"...STRONG ISENTROPIC
ASCENT EAST OF THE SFC TROUGH...AND INCREASING UPPER LEVEL
DIVERGENCE AS THE UPPER TROUGH MOVES ACROSS THE ROCKIES...WILL SEE
CHANCES FOR RAIN INCREASING FROM THE EVENING THROUGH THE OVERNIGHT.
HIGHEST QPF IS PLACED ALONG THE MISSOURI RIVER AND POINTS NORTH
AND EAST WHERE FORCING WILL BE MAXED. FOR THUNDERSTORM
CHANCES...SCALED BACK A BIT. 00Z NAM/GFS BUFFER SOUNDINGS SHOW
STEEP MID LEVEL LAPSE RATES NEAR 10C/KM SPREADING INTO MY FAR
WESTERN COUNTIES (KISN-KDIK) MID TO LATE EVENING...THEN BECOMING
SOUTHEAST TO NORTHWEST ORIENTATED EAST OF THE SFC TROUGH OVERNIGHT
OVER THE SOUTH CENTRAL AND WEST (KISN-KDIK-KBIS). WITH MUCAPE
ALMOST NON-EXISTENT...KEPT THUNDER MENTION AS ISOLATED FOR THE
ABOVE MENTIONED AREAS. REMOVED ENTIRELY NORTH CENTRAL AND EAST
(KMOT-KJMS) WITH MID LEVEL LAPSE RATES WEAKER AND STILL NO MUCAPE.

ANY SHOWER OR THUNDERSTORM ACTIVITY HAS THE POTENTIAL TO MIX TO
THE SURFACE THE WINDS ASSOCIATED WITH THE LOW LEVEL JET...WHICH
ARE DEPICTED TO RANGE FROM 50-60KTS FOR MUCH OF THE NIGHT.
MENTIONED THUNDERSTORMS WITH GUSTY WINDS IN THE HWO FOR NOW...AND
THE DAY CREW AND ESPECIALLY THE EVENING CREW WILL WANT TO TAKE
NOTICE OF THIS POSSIBILITY.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)

ISSUED AT 446 AM CDT TUE APR 22 2014

TWO VIGOROUS SYSTEMS WILL INFLUENCE THE WEATHER ACROSS WESTERN AND
CENTRAL NORTH DAKOTA IN THE LONG TERM PERIOD.

A WAVE MOVING ACROSS THE NORTHWEST U.S. AND SOUTHWEST CANADA IS
EXPECTED TO DEVELOP A CLOSED UPPER LEVEL CIRCULATION OVER SOUTHERN
BRITISH COLUMBIA/ALBERTA ON WEDNESDAY AND TRACK SLOWLY EAST ALONG
THE INTERNATIONAL BORDER THROUGH FRIDAY. STRONG SOUTHEAST FLOW AHEAD
OF THE ASSOCIATED SURFACE SYSTEM WILL BE WELL ESTABLISHED ACROSS THE
AREA AT THE BEGINNING OF THE LONG TERM PERIOD WEDNESDAY MORNING AND
WIND HIGHLIGHTS MAY BE NEEDED FROM LATE IN THE SHORT TERM PERIOD
THROUGH WEDNESDAY MORNING.

THE THREAT OF ELEVATED CONVECTION APPEARS MINIMAL WEDNESDAY MORNING
WITH LIMITED INSTABILITY AHEAD OF THE WARM FRONT THAT MOVES WEST TO
EAST DURING THE DAY. BEHIND THE WARM FRONT THE ATMOSPHERE DRIES
QUICKLY IN A WESTERLY FLOW. MINIMAL CHANGES WERE MADE TO POPS ON
WEDNESDAY...KEEPING HIGH CHANCE TO LIKELY POPS ACROSS THE NORTH AND
EAST...WITH ONLY SLIGHT CHANCE POPS IN THE FAR SOUTHWEST. HOWEVER WE
REMOVED THE MENTION OF THUNDER...WITH THE BEST INSTABILITY REMAINING
JUST SOUTH OF THE FORECAST AREA.

AS THE UPPER LOW MOVES INTO SOUTHERN SASKATCHEWAN WEDNESDAY NIGHT
LINGERING PRECIPITATION WILL END ACROSS THE FAR NORTH AND EAST WITH
A GOOD PORTION OF THE PERIOD REMAINING DRY. THE THREAT OF
PRECIPITATION THEN INCREASES ON THURSDAY AS THE UPPER LOW MOVES
ACROSS THE NORTHERN PORTION OF THE FORECAST AREA. BEST PRECIPITATION
CHANCES WILL REMAIN OVER THE NORTHERN HALF OF THE FORECAST AREA.
SHOWERS DURING THE MORNING AND POSSIBLE THUNDER THURSDAY AFTERNOON
WITH STEEP LAPSE RATES UNDER THE UPPER LEVEL LOW. AS THE LOW EXITS
THE AREA THURSDAY NIGHT...COLD CANADIAN AIR WILL FILTER INTO THE
STATE AND A MIX OF RAIN AND SNOW WILL BE POSSIBLE ACROSS THE NORTH
BY LATE THURSDAY NIGHT...WITH LIGHT RAIN OR SNOW SHOWERS LINGERING
INTO FRIDAY MORNING.

DURING THIS TIME THE NEXT STRONG SYSTEM IS TAKING SHAPE OVER THE
WESTERN U.S. MODEL UNCERTAINTY INCREASES AS WE HEAD INTO THE WEEKEND
BUT IT APPEARS THAT THE UPPER LEVEL FLOW IS TRENDING SLOWER WITH A
POSSIBLE BLOCKING PATTERN SETTING UP OVER THE CENTRAL PORTION OF THE
COUNTRY. WILL NEED TO KEEP AN EYE ON THE EVOLUTION OF THIS SYSTEM AS
LATEST DETERMINISTIC RUNS ARE COLDER AND WETTER ACROSS WESTERN AND
CENTRAL NORTH DAKOTA. UTILIZED A STRAIGHT MODEL BLEND FOR THE
EXTENDED AND THIS IS DEPICTING PRECIPITATION ACROSS MAINLY THE
SOUTHWEST ON SATURDAY...THEN SPREADING ACROSS MOST OF THE AREA
SUNDAY THROUGH MONDAY. WITH COLDER TEMPERATURES EXPECTED BY THE
WEEKEND PRECIPITATION CHANCES WERE MAINLY RAIN DURING THE AFTERNOON
AND EARLY EVENING...WITH A MIX OF RAIN AND SNOW DURING THE OVERNIGHT
AND EARLY MORNING HOURS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 636 AM CDT TUE APR 22 2014

HIGH PRESSURE CENTERED OVER MINNESOTA AND DEVELOPING LOW PRESSURE
IN MONTANA WILL COMBINE FOR INCREASING SOUTHEASTERLY WINDS ACROSS
THE REGION AFTER 12Z. THE WINDS WILL ALSO INCREASE LOW LEVEL
MOISTURE AND SUPPORT SCATTERED SHOWERS DEVELOPING TUESDAY
EVENING AND BECOMING MORE NUMEROUS LATER TUESDAY NIGHT. THERE
WILL BE A POSSIBILITY AS WELL FOR ISOLATED THUNDERSTORMS WEST IN
THE EVENING FOR KISN-KMOT. HOWEVER TOO MUCH UNCERTAINTY IN TIME
AND LOCATION TO INCLUDE IN TAFS AT THIS TIME. VFR CONDITIONS
THROUGH THE 12Z TAF PERIOD.

&&

.FIRE WEATHER...

ISSUED AT 446 AM CDT TUE APR 22 2014

A HIGH TO VERY HIGH FIRE DANGER WILL EXIST TODAY ACROSS NORTH
DAKOTA AS SOUTHEASTERLY WINDS INCREASE IN THE MORNING AND
AFTERNOON. SUSTAINED WINDS OF 20-25KTS AND MIN RH OF 25-35 PERCENT
ARE EXPECTED. A FEW HIGHER GUSTS TO 35KTS POSSIBLE WEST IN THE
LATE AFTERNOON/EARLY EVENING. RED FLAG CONDITIONS ARE NOT EXPECTED
AT THIS TIME.

&&

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

$$

UPDATE...TWH
SHORT TERM...NH
LONG TERM...TWH
AVIATION...NH
FIRE WEATHER...NH






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