Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 151507
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
907 AM MDT FRI AUG 15 2014

.UPDATE...
SLOW MOVING CUT OFF LOW CONTINUES TO PRODUCE SHOWERS TO OUR FAR
NORTHEAST...THOUGH PCPN IS NOT AS HEAVY AS LAST NIGHT AND PCPN
AREA IS BECOMING MORE SCATTERED IN FALLON COUNTY. SOME PCPN AMTS
SINCE LATE YESTERDAY EVENING INCLUDE ABOUT 0.75 INCHES AT BAKER...
1.20 INCHES AT OLLIE AND ALMOST 3 INCHES AT CANNONBALL CREEK
RAWS. THESE TOTALS AS OF 830 AM THIS MORNING.

OFF AND ON SHOWERS WILL CONTINUE FOR OUR NORTHEAST TODAY THOUGH
WITH AN OVERALL DECREASING TREND AS THE LOW DRIFTS SLOWLY EAST.
ATTENTION WILL THEN TURN TO MUCH DEEPER PACIFIC LOW TO OUR WEST.
THIS LOW HAS BEGUN A WEAKENING STAGE AND WILL DRIFT SLOWLY
NORTHEAST OVER TIME. THOUGH WE ARE BEGINNING TO DRAW DRIER AIR IN
FROM THE NORTHERN GREAT BASIN...MOISTURE DEFINITELY REMAINS ABOVE
NORMAL IN OUR WEST...WITH PWAT OF 0.88 INCHES UPSTREAM AT BOISE
AT 12Z THIS MORNING. STRONGEST DIFFLUENCE ALOFT WILL BE LOCATED
OVER OUR NW PARTS LATER TODAY AND THIS IS WHERE POTENTIAL FOR
STRONGER STORMS EXISTS...IE WEST AND NORTH OF BILLINGS. 0-6KM BULK
SHEAR EXPECTED TO RISE TO NEAR 30 KTS TODAY...ALONG WITH UP TO
1000-1500 J/KG OF CAPE...ENOUGH FOR A FEW STRONG TO PERHAPS
BORDERLINE SEVERE STORMS THIS AFTERNOON AND EVENING. SOMETHING TO
WATCH TODAY.

OTHERWISE TEMPS WILL BE NEAR NORMAL WITH HIGHS IN THE 80S...AND
MAYBE ONLY IN THE 70S NEAR BAKER PER INFLUENCE OF UPPER LOW IN THE
NORTHERN PLAINS. HAVE TWEAKED POPS AND SKY COVER DOWN THIS
MORNING IN WEST AND CENTRAL PARTS PER CURRENT CLEAR SKIES AND LACK
OF SHOWERS. HAVE ALSO TWEAKED WINDS AND TEMPS.

JKL

&&

.SHORT TERM...VALID FOR TDY AND SAT...

OUR FORECAST AREA WAS BEING INFLUENCED BY A COUPLE OF UPPER LOWS.
THE FIRST LOW WAS SITTING OVER FAR EASTERN MONTANA AT THE MOMENT.
THIS LOW HAS ABUNDANT MOISTURE AVAILABLE TO IT WITH PRECIPITABLE
WATERS AROUND 1.5 INCHES. THUS PERIODS OF HEAVY RAIN HAVE AFFECTED
CUSTER/FALLON AND NORTHERN CARTER COUNTIES. THE UPPER LOW WAS VERY
SLOWLY PUSHING NORTHEAST AS RIDGING WAS BUILDING AHEAD OF THE
OTHER UPPER LOW TO THE WEST. THIS NORTHEAST DRIFT WILL TAKE THE
BEST CHANCE OF CONVECTION OUT OF THE AREA. WILL LINGER SCATTERED
POPS FOR MOST OF THE DAY OVER THE SOUTHEAST...WITH THE HIGHEST
POPS OVER THE NORTHEAST SECTION OF THE FORECAST AREA. DRIER AIR
WAS GRADUALLY WORKING INTO SOUTHERN MONTANA...SO RAIN RATES SHOULD
NOT BE QUITE AS AGGRESSIVE TODAY. STILL COULD SEE PERIODS OF
MODERATE TO HEAVY RAINFALL.

NOT MUCH GOING ON OVER SOUTH CENTRAL ZONES AS RIDGING WAS
BUILDING UP AND DRIER AIR BEING PULLED IN AT MID LEVELS. THE UPPER
RIDGE SHOULD KEEP MOST OF THE CENTRAL AND WESTERN ZONES DRY TODAY.
THAT BEING SAID...DIFFLUENT FLOW ON THE EAST SIDE OF THE WESTERN
UPPER LOW INCREASES OVER THE WESTERN HALF OF THE AREA THIS
AFTERNOON. THIS SHOULD BE ENOUGH FOR ISOLATED TO SCATTERED
THUNDERSTORMS. THE DIFFLUENT FLOW WILL SHIFT FARTHER NORTHEAST
THIS EVENING FOR PROBABLY THE BEST CHANCE OF CONVECTION OVER THE
CENTRAL ZONES.

THE UPPER LOW DRIFTS ACROSS NORTHERN MONTANA SATURDAY AND THIS
PROVIDES A DOWNSLOPE PATTERN FOR THE FORECAST AREA. THIS WILL
CONTINUE TO DRY OUT THE AREA AS THE INCH PRECIPITABLE WATER LINE
SHIFTS TO THE MONTANA/DAKOTA BORDER. A SURFACE TROUGH WILL SLIDE
INTO FAR EASTERN MONTANA AND THIS TRANSLATES INTO MINIMAL CAPE FOR
WESTERN AND CENTRAL ZONES...DESPITE INCREASING SHEAR. THE STRONG
FORCING WILL STAY NORTH OF THE AREA...BUT WOULD NOT BE SURPRISED
TO SEE AN ISOLATED STRONG STORM OVER THE NORTHEAST PART OF THE
AREA IN THE AFTERNOON AND EVENING. WILL MAINTAIN ISOLATED TO
SCATTERED POPS FOR THE ENTIRE AREA WITH THE HIGHEST POPS OVER THE
NORTHEAST AND EAST.

TEMPERATURES WILL BE SEASONAL. DID LOWER HIGHS A COUPLE OF
DEGREES TODAY AND SATURDAY AS GUIDANCE WAS COMING IN SLIGHTLY
COOLER. TWH

.LONG TERM...VALID FOR SUN...MON...TUE...WED...THU...

CONFIDENCE IN THE EXTENDED FORECAST REMAINS FAIRLY HIGH. FORECAST
MODELS ARE IN GOOD AGREEMENT THROUGH THE END OF NEXT WEEK.
INITIALLY...NORTHWEST TO ZONAL FLOW WILL PREVAIL THROUGH
WEDNESDAY...WHICH WILL RESULT IN FAIRLY SEASONABLE AND DRY
CONDITIONS. TROUGHING WILL THEN PUSH INTO THE PACIFIC NORTHWEST BY
THE END OF NEXT WEEK...WHICH SHOULD RESULT IN A TRANSITION TO
SLIGHTLY BELOW NORMAL TEMPERATURES AND INCREASED CHANCE OF
PRECIPITATION.

...SUNDAY...
UPPER LEVEL LOW THAT IS CURRENTLY LOCATED CENTERED OVER NORTHERN
OREGON / SOUTHERN WASHINGTON WILL FINALLY BE EJECTING INTO NORTH
DAKOTA. THE FORECAST AREA WILL BE IN THE SUBSIDENT NORTHWESTERLY
DOWNSLOPE FLOW ON SUNDAY. THE TIGHTENED PRESSURE GRADIENT AND
FAIRLY UNIDIRECTIONAL NORTHWEST FLOW WILL RESULT A STRONG MIXING
AND DOWNSLOPE DAY. THE RESULT WILL BE DRY CONDITIONS ACROSS MUCH
OF THE FORECAST AREA...WITH THE EXCEPTION NEAR BAKER...ESPECIALLY
IN THE MORNING. INCREASED HIGH TEMPERATURES SLIGHTLY...AND TRIED
TO KEEP THEM ON WARM SIDE OF THE GUIDANCE ENVELOPE. SOME
LINGERING CLOUD COVER BEHIND THE WAVE COULD BE A LIMITING FACTOR
TO TEMPERATURES...BUT ONCE SYNOPTIC SUBSIDENCE AND DOWNSLOPE FLOW
BECOME WELL ESTABLISHED BY AFTERNOON SHOULD SEE RESPECTABLE
CLEARING.

...MONDAY THROUGH WEDNESDAY...
THE FLOW ALOFT WILL SLOWLY TRANSITION TO ZONAL AND THEN TO
SLIGHTLY SOUTHWESTERLY AHEAD OF A DEVELOPING TROUGH ALONG THE
PACIFIC NORTHWEST COAST. AS THE FLOW SLOWLY SHIFTS AROUND...WE
WILL SEE GRADUALLY INCREASING HIGH TEMPERATURES...AND
PRECIPITATION CHANCES. MONDAY WILL BE A DRY DAY FOR THE FORECAST
AREA. BY TUESDAY SOME INCREASING MOISTURE WILL ALLOW FOR A SLIGHT
CHANCE OF SHOWERS AND THUNDERSTORMS IN THE MOUNTAINS. WEDNESDAY
WILL SEE THE SLIGHT CHANCE OF STORMS SPREAD INTO THE PLAINS.

...THURSDAY AND BEYOND...
LAST WEEK...THE MODELS STARTED HINTING AT A PATTERN CHANGE FOR THE
END OF NEXT WEEK...WITH TROUGHING BUILDING IN ALONG THE WEST
COAST...AND RIDGING BUILDING IN OVER THE EASTERN CONUS. MODELS
REMAIN FAIRLY LOCKED IN ON THAT SOLUTION TODAY. THE CHANGE IN THE
PATTERN SEEMS TO BE RELATED TO A BREAK DOWN OF THE JET STREAM
OVER THE PACIFIC OCEAN...WHICH ALLOWS FOR A STRONG RIDGE TO BUILD
INTO THE GULF OF ALASKA. THUS WE SEE DOWNSTREAM DEVELOPMENT OF A
TROUGH INTO THE FORECAST AREA IN THE THURSDAY/FRIDAY TIME FRAME.
WHILE THERE ARE STILL SOME DETAILS TO IRON OUT...IN TERMS OF THE
MAGNITUDE OF THE TROUGH...EXPECT TO SEE A TURN TOWARD COOLER AND
WETTER BY THE WEEK/S END.

CHURCH

&&

.AVIATION...

SHOWERS AND THUNDERSTORMS CONTINUE TO LINGER NEAR KMLS AND KBHK
THIS MORNING...WITH SOME LOCALIZED MVFR/IFR CONDITIONS IN
STRONGER CELLS. ISOLATED/SCATTERED SHOWERS AND THUNDERSTORMS ARE
POSSIBLE ACROSS THE REGION THIS AFTERNOON AND EVENING...WITH BEST
POTENTIAL OVER AREA MOUNTAINS. LOCALIZED MVFR/IFR FLIGHT
CONDITIONS AND OCCASIONAL MOUNTAIN OBSCURATIONS CAN BE EXPECTED
WITH SHOWERS. OTHERWISE...VFR CONDITIONS WILL PREVAIL THROUGH
THE TAF PERIOD. AAG


&&

.PRELIMINARY POINT TEMP/POPS...

    TDY SAT     SUN     MON     TUE     WED     THU
-------------------------------------------------------
BIL 086 061/087 061/089 060/087 061/091 062/090 061/086
    2/T 32/T    21/B    11/B    11/U    22/T    23/T
LVM 085 052/083 052/088 052/087 053/090 053/088 052/084
    4/T 42/T    21/B    11/B    11/U    22/T    23/T
HDN 087 058/089 058/092 059/089 059/093 060/092 059/089
    2/T 32/T    21/B    11/B    11/U    22/T    23/T
MLS 084 062/089 061/089 062/087 062/091 063/092 061/087
    5/T 44/T    32/T    21/B    11/U    22/T    23/T
4BQ 085 061/089 060/089 061/087 060/091 061/093 060/089
    3/T 33/T    22/T    21/B    11/B    22/T    22/T
BHK 079 057/087 056/086 058/084 055/088 057/089 056/085
    +/T 44/T    44/T    32/T    21/B    22/T    23/T
SHR 085 054/086 054/088 055/086 055/090 056/091 055/087
    2/T 32/T    21/B    11/U    11/U    22/T    23/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS


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