Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 162128
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
328 PM MDT WED JUL 16 2014

.SHORT TERM...VALID FOR THU AND FRI...

A ZONAL FLOW ALOFT WILL BE OVER THE FORECAST AREA THROUGH FRIDAY
WITH NO STRONG UPPER LEVEL WAVES EXPECTED. SURFACE HIGH PRESSURE
WILL BE OVER THE AREA TONIGHT RESULTING IN CLEAR TO MOSTLY CLEAR
SKIES. THURSDAY WILL CONTINUE TO SEE MOSTLY SUNNY SKIES BUT A LEE-
SIDE TROUGH WILL SET UP AS A SURFACE LOW MOVES ACROSS SOUTHERN
CANADA. WINDS WILL BECOME SOUTHWESTERLY ACROSS OUR CENTRAL AND
WESTERN AREAS ALLOWING FOR A DRY AND HOT DOWNSLOPE FLOW.
HOWEVER...A SMALL JET STREAK WILL MOVE ACROSS IDAHO INTO WESTERN
WYOMING AND THIS MAY TRIGGER AN AFTERNOON/EVENING THUNDERSTORM
OVER THE MOUNTAINS BUT MOISTURE LOOKS TO BE VERY LIMITED.

AS THE ABOVE MENTIONED SURFACE LOW MOVES EAST...IT WILL SWEEP A
"COLD FRONT"...MORE LIKE A WIND SHIFT...ACROSS THE FORECAST AREA
THURSDAY NIGHT INTO FRIDAY MORNING. THIS COMBINED WITH A WEAK
DISTURBANCE MOVING THROUGH THE FLOW ALOFT THURSDAY NIGHT INTO
FRIDAY WILL ALLOW FOR A SLIGHT SHOWER OR THUNDERSTORM CHANCE.
850MB THERMAL RIDGE WILL CONTINUE TO BUILD THURSDAY INTO FRIDAY
WITH TEMPERATURES AROUND 30C RESULTING IN HOT AFTERNOON
TEMPERATURES IN THE LOWER TO MIDDLE 90S ALONG WITH WARM OVERNIGHT
LOWS. HOOLEY

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

FORECAST CONFIDENCE WAS HIGHEST THROUGH MON...ALTHOUGH THERE WERE
MODEL DIFFERENCES IN RESOLVING VARIOUS FEATURES OF THE PATTERN. AFTER
MON...ENSEMBLES DISPLAYED DIFFICULTY IN RESOLVING THE EVOLUTION OF
A PACIFIC TROUGH APPROACHING THE AREA...SO CONFIDENCE WAS LOWEST
LATER IN THE PERIOD.

CONTINUED THE DRY FORECAST FOR SAT AND SAT NIGHT. THE ECMWF HAD
THE REGION UNDER ZONAL FLOW WHILE THE GFS TURNED THE FLOW SW WITH
TIME. MONSOONAL AND PACIFIC MOISTURE WAS LIMITED DURING THIS TIME.
GOOD MIXING AND 700 MB TEMPERATURES RANGING FROM +12 TO +16 C
SUPPORTED HIGH TEMPERATURES WELL INTO THE 90S ON SAT. JET ENERGY
WILL BEGIN TO INCREASE OVER THE AREA FROM THE N AND S ON SUN. PRECIPITABLE
WATERS WILL INCREASE AS WELL...DUE TO AN INFLUX OF PACIFIC AND
MONSOONAL MOISTURE. THE GFS REMAINED MORE SW WITH THE FLOW THAN
THE ECMWF...BUT BOTH MODELS SHOWED A COLD FRONT MOVING THROUGH THE
WESTERN ZONES IN THE AFTERNOON. SPREAD SLIGHT CHANCE POPS E
THROUGH THE AREA BEGINNING SUN AFTERNOON AND HAD THEM ACROSS THE
ENTIRE AREA LATE SUN NIGHT AS THE FRONT CONTINUED TO CROSS THE
AREA. SUN TEMPERATURES WILL BE SIMILAR TO SAT/S READINGS EXCEPT A
LITTLE COOLER IN THE W DUE TO CLOUD COVER.

A JET FROM THE SW WILL CONTINUE TO INFLUENCE THE REGION ON MON.
HOWEVER...THERE WILL BE A BIT OF A BREAK IN THE MOISTURE SO KEPT
POPS CONFINED TO AREAS OVER AND NEAR THE MOUNTAINS. MOISTURE
INCREASED AGAIN MON NIGHT SO HAD SLIGHT CHANCES OVER MUCH OF THE
AREA. GFS CONTINUED SW FLOW OVER THE REGION TUE AND TUE NIGHT...WHILE
THE ECMWF SHOWED A HIGH PRESSURE RIDGE AMPLIFYING OVER THE AREA.
FOR NOW...CONTINUED THE POPS W OF KBIL IN THE AFTERNOON AND
EVENING. BOTH MODELS RETURNED TO SW FLOW OVER THE REGION LATE ON
WED...BUT DIFFERED IN THEIR HANDLING OF AN APPROACHING PACIFIC
TROUGH. ADDED LOW POPS TO MAINLY THE WESTERN ZONES. MODELS DID
NOT AGREE IN THEIR THERMAL PROFILES MON THROUGH WED SO DID NOT
CHANGE TEMPERATURES AT THIS TIME WHICH WERE IN THE 90S. ARTHUR
&&

.AVIATION...

THERE WILL BE A SLIGHT CHANCE OF THUNDERSTORMS OVER THE NE BIG
HORN MOUNTAINS INTO THIS EVENING...OTHERWISE THE AREA WILL BE DRY
WITH VFR CONDITIONS THROUGH THU MORNING. EXPECTED LOCALIZED
OBSCURATIONS OVER THE NE BIG HORNS THIS EVENING. THERE WILL BE A
SLIGHT CHANCE OF THUNDERSTORMS W AND N OF KBIL...AND OVER THE NE
BIG HORNS THU AFTERNOON. MVFR WILL BE POSSIBLE WITH THE
THUNDERSTORMS. EXPECT LOCALIZED OBSCURATIONS OVER THE MOUNTAINS.
ARTHUR
&&

.PRELIMINARY POINT TEMP/POPS...

    THU     FRI     SAT     SUN     MON     TUE     WED
-----------------------------------------------------------
BIL 059/091 064/093 063/095 062/093 062/094 061/095 062/092
    01/U    21/U    21/U    11/U    21/U    21/U    11/U
LVM 052/089 053/090 054/091 056/088 056/088 055/093 054/088
    02/T    32/T    21/U    12/T    22/T    22/T    22/T
HDN 056/093 060/094 060/096 063/095 062/096 061/097 062/094
    01/U    21/U    21/U    11/U    21/U    21/U    11/U
MLS 059/093 065/095 064/094 065/096 065/097 064/097 065/091
    01/U    21/U    11/U    11/U    21/U    21/U    11/U
4BQ 057/090 060/093 062/094 063/097 063/097 062/097 064/092
    01/U    21/U    11/U    11/U    21/U    11/U    11/U
BHK 054/089 060/092 060/093 062/095 062/094 061/094 060/089
    00/U    11/U    11/U    11/U    21/U    11/U    11/U
SHR 052/088 057/090 058/092 058/093 058/092 057/094 058/092
    01/U    22/T    21/U    12/T    21/U    21/U    11/U

&&

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

&&

$$
WEATHER.GOV/BILLINGS


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