Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 172106
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
306 PM MDT SUN AUG 17 2014

.SHORT TERM...VALID FOR MON AND TUE...

CYCLONIC AND MODESTLY UNSTABLE NORTHWEST FLOW ALOFT WILL PRODUCE
ISOLATED TO WIDELY SCATTERED SHOWERS AND A FEW TSTMS ACROSS MAINLY
OUR EAST INTO THIS EVENING. W-NW WINDS HAVE BECOME GUSTY AS
EXPECTED...AND THE DOWNSLOPE FLOW WILL HINDER THE SHOWER ACTIVITY
IN OUR WEST. MILES CITY HAS RECENTLY MIXED OUT A DEWPT IN THE MID
40S...SO WITH THE DRIER AIR IN MIND HAVE SCALED BACK POPS SLIGHTLY
IN OUR EAST AS WELL...THOUGH WITH A SHORTWAVE DROPPING OUT OF THE
NW FLOW WE SHOULD SEE SOME INCREASE IN SHOWERS OVER THE NEXT FEW
HOURS. NOT MUCH GOING ON AS OF 230 PM WITH THE EXCEPTION OF A
COUPLE CELLS ALONG THE DAKOTAS BORDER WHICH WILL SHIFT EAST OF OUR
CWA SHORTLY. OTHERWISE TONIGHT WILL BE A LITTLE COOLER AS WE TAP
INTO A PIECE OF CANADIAN AIR.

WEAK UPPER RIDGE WILL BUILD IN FOR MONDAY GIVING A DRY DAY FOR
MOST OF THE CWA...THE EXCEPTION BEING OUR MTNS AND FOOTHILLS
WHICH SHOULD SEE ISOLATED WEAK CONVECTION IN RESPONSE TO PV COMING
OUT OF THE NORTHERN GREAT BASIN. PWATS TO OUR SW REMAIN ABOVE
NORMAL SO THERE IS SOME CONFIDENCE HERE. GUSTY NW WINDS WILL
LINGER IN OUR EAST DUE TO THE SLOW DEPARTURE OF NORTHERN PLAINS
TROUGH. TEMPS ON MONDAY WILL BE NEAR NORMAL WITH HIGHS MOSTLY IN
THE 80S.

RIDGE AXIS WILL SHIFT TO THE EAST AND OPEN THE DOOR TO STRONGER
SHORTWAVE ENERGY FROM THE SOUTHWEST ON TUESDAY...AND THUS A
GREATER CHANCE OF STORMS. SFC TEMPS INTO THE LOW 90S AND STEEP LOW
LEVEL LAPSES COULD RESULT IN SOME STRONG WIND GUSTS WITH ANY
CONVECTION COMING OFF THE HIGH TERRAIN IN THE LATE AFTERNOON AND
EVENING. THE THREAT OF TSTMS EXISTS IN OUR EAST TOO AS SHORTWAVE
LIFTS THROUGH NORTHEAST WY BY EVENING...ALONG WITH INCREASED
SOUTHEASTERLY LOW LEVEL FLOW AND MOISTURE ADVECTION. HAVE EXPANDED
POPS IN OUR SW SLIGHTLY...AND RAISED TEMPS A BIT ON TUESDAY.

JKL

.LONG TERM...VALID FOR WED...THU...FRI...SAT...SUN...

COOLER AND WETTER WEATHER CAN BE EXPECTED THROUGHOUT THE EXTENDED
PERIOD...WITH A SLOW MOVING TROF DOMINATING THE WEATHER OVER THE
WESTERN CONUS. ALTHOUGH SOME DETAILS ARE STILL UNCERTAIN AS TO
POSSIBLE INTERACTION WITH CUTOFF LOW IN OVER SOUTHERN CALIFORNIA
COAST...MODELS CONTINUE TO POINT TOWARD A MUCH COOLER AIRMASS
COMING INTO THE REGION.

WEDNESDAY WILL BEGIN THE COOLING TREND...AS FIRST SHORTWAVE
COMPLETES PASSAGE THROUGH THE REGION AND MAIN UPPER TROF CONTINUES
TO DEEPEN IN THE WEST. WE ALSO APPEAR TO REMAIN TAPPED INTO
MONSOONAL FLOW AT THIS TIME...SO POP POTENTIAL WILL
CONTINUE...WITH SHORTWAVE ACTIVITY. THE UPPER TROF DEEPENS AND
SLOWLY SHIFTS EASTWARD THROUGH THE REMAINDER OF THE EXTENDED
PERIOD...WITH CONTINUING POTENTIAL FOR SHOWERS AND THUNDERSTORMS
THROUGH THE WEEKEND. TEMPS APPEAR AS THOUGH SHOULD BOTTOM OUT ON
SATURDAY WITH HIGHS IN UPPER 60S AND LOWER 70S AT BEST...AND HAVE
COOLED TEMP FORECAST THROUGHOUT THE PERIOD. A STARK CHANGE TO THE
PATTERN IS ALSO EXPECTED IN THE WAY OF PRECIP INTO THE REGION.
PLACEMENT AND SLOW PROGRESSION OF THE TROF WILL KEEP SHOWER AND
THUNDERSTORM POTENTIAL IN PLACE THROUGHOUT THE PERIOD AS WELL.
HAVE GENERALLY TRENDED POPS UPWARD THROUGHOUT THE PERIOD AS WELL.

ONE OF THE MOST INTERESTING ASPECTS OF THIS FORECAST IS MODELS
INDICATING 700MB TEMPS OF 0 TO 2 DEGREES BELOW ZERO ACROSS THE
REGION ON SATURDAY. THIS WOULD BRING THE POTENTIAL FOR SNOW...YES
SNOW TO THE HIGHER TERRAIN AROUND THE AREA...INCLUDING POSSIBLY
BEARTOOTH PASS. AS A SIDE NOTE...THESE TEMPS HAVE BEEN GENERALLY
TRENDING COOLER IN SUCCESSIVE MODEL RUNS.

WE ARE STILL KEEPING AN EYE ON WHAT WILL HAPPEN WITH POTENTIAL
CUTOFF LOW IN THE SOUTHERN CALIFORNIA AREA...BUT IT APPEARS AT
THIS TIME THAT IMPACTS WOULD MAINLY BE FOR EXTREME EASTERN MONTANA
AND THE DAKOTAS. AAG

&&

.AVIATION...

ISOLATED SHOWERS AND THUNDERSTORMS CONTINUE TO DEVELOP IN
SOUTHEASTERN MONTANA...AND MOVE OFF INTO THE DAKOTAS. ADDITIONAL
ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE...BUT WILL BE
CLEARING EAST YET THIS EVENING. MVFR/IFR CONDITIONS ARE POSSIBLE
ALONG WITH GUSTY WINDS IN ANY OF THE STRONGER CELLS.
OTHERWISE...VFR CONDITIONS WILL PREVAIL FOR ALL ROUTES TODAY. AAG

&&

.PRELIMINARY POINT TEMP/POPS...

    MON     TUE     WED     THU     FRI     SAT     SUN
-----------------------------------------------------------
BIL 058/087 061/092 063/084 058/080 057/076 053/070 051/074
    21/U    12/T    33/T    33/T    45/T    54/T    33/T
LVM 049/089 053/091 053/080 051/077 049/073 047/068 048/071
    12/T    22/T    34/T    44/T    45/T    54/T    43/T
HDN 055/089 058/093 059/085 054/084 056/080 054/073 052/076
    21/B    12/T    22/T    33/T    35/T    54/T    33/T
MLS 060/087 061/092 064/085 058/083 059/078 055/072 053/074
    31/B    11/U    22/T    33/T    45/T    54/T    33/T
4BQ 058/086 059/091 061/085 058/085 059/082 057/072 054/075
    21/U    12/T    23/T    43/T    45/T    54/T    32/T
BHK 056/083 055/088 059/083 054/082 055/078 056/071 055/071
    31/B    11/U    23/T    43/T    45/T    53/T    33/T
SHR 052/086 054/091 055/083 052/083 053/079 051/070 049/073
    21/U    12/T    32/T    33/T    34/T    44/T    32/T

&&

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

&&

$$
WEATHER.GOV/BILLINGS


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