Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 220952
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
352 AM MDT FRI MAY 22 2015

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

A DEEP UPPER LOW WAS PUSHING INTO SOUTHERN CALIFORNIA THIS HOUR.
THIS SYSTEM WILL BE RESPONSIBLE FOR OUR RELATIVELY UNSETTLED
FORECAST THROUGH THE WEEKEND. THE UPPER LOW WILL PUSH INTO
SOUTHERN NEVADA EARLY THIS AFTERNOON. A PIECE OF ENERGY OUT AHEAD
OF THE UPPER LOW...OVER NORTHEAST NEW MEXICO...WILL MOVE INTO EAST
CENTRAL WYOMING THIS AFTERNOON. THIS ENERGY WILL SPREAD CLOUDS AND
SHOWERS INTO THE FORECAST AREA. THE HIGHEST POPS WILL BE NEAREST
THE MOUNTAINS WITH UPSLOPE FLOW. ENOUGH INSTABILITY FOR ISOLATED
THUNDERSTORMS...MAINLY WEST. WEAK MID LEVEL FLOW WILL PRODUCE
PULSING ACTIVITY AND SO CELL WILL HAVE A HARD TIME MOVING OFF THE
FOOTHILLS.

THE UPPER LOW MOVES INTO COLORADO ON SATURDAY AND PUSHES THE
EASTERN ENERGY INTO SOUTHEAST MONTANA. THE GFS WAS STRONGER AND
FARTHER EAST WITH THIS ENERGY AND THUS HAS MORE QPF OVER SOUTHEAST
MONTANA. DID RAISE POPS OVER THE SOUTHEAST AS EVEN THE FARTHER
EAST ECMWF BROUGHT FORCING IN. UPSLOPE FLOW WILL KEEP SCATTERED
SHOWERS GOING OVER WESTERN AND CENTRAL ZONES WITH THE HIGHEST POPS
OVER THE WEST. ENOUGH INSTABILITY FOR THUNDER BUT SHOULD BE
LIMITED. MORE CLOUDS AND NORTHEAST WINDS AT 850MB WILL PROVIDE A
COOLER DAY ON SATURDAY. HIGHS TODAY SHOULD BE AROUND 70...WITH 60S
ON SATURDAY. TWH

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

SUNDAY...A LOW OVER THE DAKOTAS WILL CONTINUE TO PUSH EAST. THIS
WILL CONTINUE SLIGHT RAIN CHANCES ACROSS THE AREA...WITH BETTER
CHANCES FROM MILES CITY AND BROADUS EAST...AS PRECIP WRAPS AROUND
THE BACKSIDE OF THE LOW. THE GFS IS MUCH MORE AGGRESSIVE WITH
GENERATING QPF THAN THE ECMWF. GIVEN HOW THE GFS SEEMS TO HAS BEEN
OVERLY AGGRESSIVE WITH SEVERAL PAST SYSTEMS...NOT OVERLY CONFIDENT
WITH ITS AMOUNTS.

AFTER SOME BRIEF...WEAK RIDGING MONDAY INTO TUESDAY...ANOTHER LOW
SETS UP OVER THE PACIFIC NORTHWEST. THE GFS IS MUCH SLOWER AT
PROGRESSING THIS SYSTEM THAN THE EC. WITH EITHER SOLUTION...THE
AREA LOOKS TO SEE UNSETTLE SOUTHWEST FLOW ALOFT ALONG WITH EASTERLY
SURFACE FLOW. THIS WILL SEE PWAT VALUES INCREASING ACROSS THE
AREA. THOUGH THE REMAINDER OF THE EXTEND THERE WILL BE SLIGHT
CHANCES FOR RAIN ACROSS THE AREA...WITH THE HIGHEST CHANCES OVER
THE MOUNTAINS. GIVEN THE HIGHER PWATS...HEAVY RAIN IS A
POSSIBILITY. SOME INSTABILITY EXISTS DURING THE AFTERNOONS...SO
CANNOT RULE OUT AN ISOLATED THUNDERSTORM.

TEMPERATURES WILL GENERALLY BE NEAR SEASONAL NORMALS THROUGH THE
EXTENDED ALTHOUGH SUNDAY WILL BE COOLER AS THE LOW DEPARTS THE
AREA. REIMER

&&

.AVIATION...

EXPECT VFR CONDITIONS OVER THE NEXT 24 HOURS. SOME AFTERNOON
THUNDERSTORMS ARE POSSIBLE MOSTLY OVER THE MOUNTAINS...AND WILL
LIKELY DISSIPATE AFTER MOVING OFF THE HIGHER TERRAIN. SOME BRIEF
MVFR TO IFR CONDITIONS ALONG WITH GUSTY WINDS ARE POSSIBLE WITH
THESE THUNDERSTORMS. REIMER

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY SAT     SUN     MON     TUE     WED     THU
-------------------------------------------------------
BIL 072 046/064 046/060 045/070 047/072 048/071 049/071
    3/T 23/T    23/T    32/T    23/T    33/T    33/T
LVM 067 044/062 042/061 040/067 043/068 043/066 044/069
    4/T 35/T    33/T    33/T    34/T    44/T    43/T
HDN 073 045/065 046/061 045/071 046/074 048/074 048/074
    3/T 23/T    33/T    32/T    23/T    33/T    33/T
MLS 073 046/064 046/062 047/067 046/073 049/072 049/071
    1/N 13/T    45/T    43/T    32/T    33/T    33/T
4BQ 069 043/059 046/058 046/065 045/072 048/071 048/070
    2/T 25/T    56/T    53/T    33/T    33/T    34/T
BHK 069 042/060 044/061 046/065 043/069 046/070 047/069
    1/N 15/T    47/T    65/T    43/T    33/T    33/T
SHR 065 041/059 043/056 041/065 042/070 045/070 045/069
    3/T 25/T    55/T    33/T    34/T    43/T    33/T

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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