Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 290308
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
908 PM MDT THU AUG 28 2014

.UPDATE...
THUNDERSTORM DEVELOPMENT ON TRACK THOUGH DEWPOINT DEPRESSIONS
FAVOR OUTFLOW WINDS RATHER THAN RAIN HITTING THROUGH GROUND AT
LEAST FOR THE NEXT FEW HOURS. UPDATED FORECAST TO INDICATE MORE
ACTIVITY NORTH OF I94 FOR THE REST OF THE NIGHT. BORSUM

&&

.SHORT TERM...VALID FOR FRI AND SAT...

AN ACTIVE PERIOD OF WEATHER WAS HEADING INTO THE FORECAST AREA.
THIS CHANGE WILL BE COURTESY OF A TROUGH CURRENTLY DIGGING OFF THE
BRITISH COLUMBIA COAST. THIS TROUGH WILL WORK INTO THE NORTHERN
ROCKIES AND TURN THE WEATHER PATTERN COOLER AND UNSETTLED. AN
INITIAL SHORTWAVE WILL SHOOT OUT AHEAD OF THE MAIN TROUGH THIS
EVENING AND GENERATE LIFT TONIGHT. SHORT RANGE MODELS...INCLUDING
THE NSSL WRF...WERE CONSISTENT ON DEVELOPING ACTIVITY OVER THE
WEST BY MID EVENING AND SPREADING IT INTO BILLINGS BY LATE
EVENING. HAVE RAISED POPS TONIGHT FOR THIS. NOT MUCH GOING ON AT
THE MOMENT...JUST A FEW CU TO THE WEST...BUT WILL KEEP SCATTERED
POPS IN PLACE AND STICK WITH A LATER DEVELOPMENT IDEA.

THE SHORTWAVE WILL SHIFT OUT OF THE EAST FRIDAY MORNING. DID
LINGER LOW POPS IN THE MORNING MOST LOCATIONS WITH A DRYING TREND
LATE MORNING TO EARLY AFTERNOON. A COLD FRONT WILL RUSH THROUGH
THE AREA TONIGHT AND EARLY FRIDAY AND THIS SHOULD KEEP HIGHS IN
THE 70S FRIDAY...ALONG WITH PROVIDING GUSTY WINDS OVER THE EAST
FRIDAY AFTERNOON. MOST OF FRIDAY NIGHT SHOULD BE QUIET AS A SMALL
SCALE RIDGE MOVES IN AHEAD OF THE NEXT UPSTREAM TROUGH.

THIS TROUGH IS PROGGED TO SLIDE IN SATURDAY WITH A COUPLED JET
PATTERN SETTING UP OVER WESTERN AND CENTRAL ZONES. THIS PROVIDES
STRONG FORCING WITH AN UNSTABLE ATMOSPHERE. HAVE RAISED POPS AS
QPF HAS COME IN QUIET WET FOR THE WESTERN AND CENTRAL ZONES WITH
UP A QUARTER INCH OF RAIN POSSIBLE...WITH UP TO A HALF INCH OVER
THE MOUNTAINS AND FOOTHILLS. A COLD FRONT WILL WORK INTO SOUTHEAST
ZONES EARLY SATURDAY AFTERNOON. RETURN FLOW OF MOISTURE MAY NOT BE
QUICK ENOUGH FOR STRONG CAPE OVER FALLON AND CARTER COUNTIES BUT
MODELS PROGG CAPES REACHING TO AROUND 1000 J/KG WITH INCREASING
SHEAR. SPC HAS FALLON COUNTY IN A SLIGHT RISK. COULD BE A BRIEF
STRONG STORM OVER THE FAR SOUTHEAST SATURDAY AFTERNOON BEFORE THE
FRONT SWEEPS THE HIGHEST CAPES EAST. REINFORCING ENERGY MOVES IN
FOR SATURDAY NIGHT AND HAVE THUS EXTENDED SCATTERED POPS INTO THE
OVERNIGHT HOURS AS THE GFS MODEL WAS WET FOR THIS PERIOD. HIGHS
SATURDAY WILL BE HELD DOWN DUE CLOUDS AND SHOWERS AROUND ALONG
WITH BEING BEHIND THE COLD FRONT. TWH

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

THE LABOR DAY WEEKEND WILL ROUND OUT WITH A LOW CHANCE FOR SHOWERS
AND THUNDERSTORMS AND SEASONABLY COOL TEMPERATURES SUN INTO MON AS
A BROAD UPPER-LEVEL TROUGH CROSSES THE REGION. THE 12 UTC GUIDANCE
SUGGESTS MON AFTERNOON AND EVENING WILL OFFER THE SLIGHTLY GREATER
/ALBEIT STILL RELATIVELY LOW/ CHANCE OF SHOWERS AND STORMS BETWEEN
THOSE TWO DAYS AS A SHORTWAVE TROUGH EMBEDDED IN THE NORTHWESTERLY
FLOW INDUCED BY THE LARGER-SCALE TROUGH CROSSES THE AREA. THE FLOW
ALOFT ACROSS THE LOWER 48 WILL TAKE ON A DECIDEDLY ZONAL LOOK NEXT
WEEK THOUGH AND A WARMING TREND WILL THUS FOLLOW AS THERMAL FIELDS
RECOVER UNDER RISING HEIGHTS TUE AND WED. HIGHS SHOULD RECOVER OFF
SUN VALUES IN THE LOWER 70S BACK TO THE LOWER 80S IN MANY SPOTS BY
BY WED.

BY NEXT THU...CONFIDENCE IN THE FORECAST DECREASES AS THE GUIDANCE
HAS BEEN OFFERING SOME MIXED SIGNALS ON THE DEGREE AND TIMING THAT
500-MB HEIGHTS MAY TEMPORARILY AMPLIFY IN THE NORTHEASTERN PACIFIC
OCEAN...WHICH COULD CAUSE A DOWNSTREAM TROUGH TO SWING THROUGH THE
REGION AGAIN BY LATE NEXT WEEK. IN RESPECT TO THAT POTENTIAL WHILE
ACKNOWLEDGING OUR MODEST CONFIDENCE IN ITS DETAILS...WE ONCE AGAIN
HAVE A SLIGHT CHANCE OF SHOWERS AND STORMS WITH A BIT COOLER HIGHS
/WHICH WERE DRIVEN BY THE MEAN OF WIDE-RANGING GUIDANCE VALUES/ IN
THE FORECAST FOR NEXT THU. SCHULTZ

&&

.AVIATION...

SCATTERED SHOWERS AND THUNDERSTORMS WILL SPREAD EASTWARD ACROSS
THE AREA TONIGHT ACCOMPANIED BY MVFR TO IFR CONDITIONS. THE
PRECIPITATION WILL BE MAINLY E OF KBIL AFTER 12Z FRI. EXPECT AREAS
OF MOUNTAIN OBSCURATION OVER THE CRAZYS...BEARTOOTHS AND ABSAROKAS
THROUGH THE NIGHT WITH INCREASING OBSCURATION OVER THE NE BIG
HORNS. LOCALIZED TO AREAS OF MOUNTAIN OBSCURATION WILL CONTINUE
OVER THE AREA ON FRI. ARTHUR
&&

.PRELIMINARY POINT TEMP/POPS...

    FRI     SAT     SUN     MON     TUE     WED     THU
-----------------------------------------------------------
BIL 059/078 057/075 052/071 050/073 050/076 052/080 053/074
    42/W    05/T    52/T    22/T    21/U    11/U    22/T
LVM 051/079 052/072 045/068 043/071 044/076 045/079 046/075
    42/W    16/T    62/T    22/T    21/U    12/T    22/T
HDN 058/080 057/078 053/072 051/075 051/078 052/082 054/078
    32/W    05/T    52/T    22/T    21/U    11/U    22/T
MLS 060/078 059/079 055/073 052/075 053/078 054/082 055/077
    34/W    03/T    52/T    22/T    21/U    11/U    22/T
4BQ 059/080 058/085 053/071 051/074 052/078 053/083 056/078
    13/T    04/T    52/T    22/T    21/B    11/U    22/T
BHK 057/076 056/079 054/071 048/073 049/076 051/080 053/076
    25/T    14/T    52/T    22/T    21/B    11/U    22/T
SHR 055/079 054/080 052/069 047/073 046/078 048/082 051/079
    22/W    04/T    42/T    22/T    21/U    11/U    22/T

&&

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

&&

$$
WEATHER.GOV/BILLINGS


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