Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 260259
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
859 PM MDT MON MAY 25 2015

.UPDATE...

CONVECTION IS DIMINISHING QUICKLY AS EXPECTED IN MOST AREAS AS THE
BOUNDARY LAYER COOLS AND STABILIZES. THE ACTIVITY UPSTREAM ACROSS
SOUTHWESTERN MT AND ID IS ASSOCIATED WITH A MORE WELL-DEFINED WAVE
ALOFT AND THUS SUPPORTS A CONTINUATION OF POPS OVERNIGHT IN SOUTH
CENTRAL MT.

FOR THIS UPDATE...ALL WE DID WAS EXPAND THE MENTION OF PATCHY FOG
TONIGHT INTO ALL OF SOUTHEASTERN MT...AND RAISE FORECAST LOWS A
BIT AS WELL. BOTH OF THOSE MOVES ARE IN RESPECT TO OBSERVED DEW
POINTS OF 45 TO 50 F AS OF MID-EVENING AND AN EXPECTATION OF
LIGHT WINDS OVERNIGHT. SCHULTZ

&&

.SHORT TERM...VALID FOR TUE AND WED...

REGION IS BRIEFLY IN BETWEEN SYSTEMS TONIGHT WITH AFTERNOON
SHOWER ACTIVITY EXPECTED TO WEAKEN WITH LOSS OF DIURNAL HEATING.
NEXT SYSTEM MOVING SLOWLY ACROSS NORTHERN WASHINGTON BEGINS
SPREADING A DIFFLUENT FLOW ALOFT OVER THE WESTERN ZONES WHICH
ALLOWS ANOTHER ROUND OF PRECIPITATION TO BEGIN DEVELOPING TOWARDS
DAYBREAK. THIS SYSTEM MOVES LITTLE ON TUESDAY SO FLOW ALOFT WILL
BE WEAK BUT AIRMASS BECOMES MORE UNSTABLE WITH WARMER SURFACE
TEMPERATURES. SHOULD SEE MORE THUNDERSTORM ACTIVITY THAN RECENT
DAYS WITH BETTER COVERAGE OVER THE WESTERN HALF OF THE AREA WITH
THE FLOW ALOFT REMAINS WEAKLY DIFFLUENT.

UPPER LOW MAKES LITTLE MOVEMENT TUESDAY NIGHT AND FLOW ALOFT
REMAINS LIGHT AND SLIGHTLY DIFFLUENT. WEAK HEIGHT FALLS AND HIGH
PRECIPITABLE WATERS SHOULD COMPENSATE FOR LOSS OF DIURNAL HEATING
TO ALLOW SHOWER ACTIVITY TO CONTINUE OVERNIGHT...ESPECIALLY FOR
WESTERN AREAS. GIVEN THE MOISTURE AND UNSTABLE AIRMASS DIURNAL
HEATING ON WEDNESDAY WILL AGAIN YIELD SHOWER AND THUNDERSTORM
ACTIVITY WITH SLOW MOVEMENT SO LOCALLY HEAVY RAIN COULD BE
POSSIBLE. HEIGHTS BUILD A BIT OVERNIGHT WEDNESDAY NIGHT TO BRING
DECREASING SHOWER ACTIVITY.

TEMPERATURES WILL BE SEASONABLE THE NEXT FEW DAYS.

HYRDOLOGICALLY ADDITIONAL RAIN THE NEXT FEW DAYS SHOULD NOT
STRONGLY CONTRIBUTE TO PROBLEMS BUT SHOULD SLOW THE FALL IN AREAS
THAT CURRENTLY HAVE HIGH WATER.

BORSUM

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

SLOW MOVING UPPER LOW WILL TRACK FROM THE PAC NW ACROSS THE
NORTHERN GREAT BASIN WED/THU REACHING THE CENTRAL ROCKIES FRI.
SOME MODEL DISAGREEMENT EXISTS IN ITS EXACT TRACK...BUT THERE IS
POTENTIAL FOR ENHANCED PCPN IN OUR SOUTHERN FOOTHILL AREAS IN THE
THU/FRI TIME FRAME PER A PERIOD OF DEEP UPSLOPE FLOW AND BROAD
SYNOPTIC SCALE ASCENT. THIS WOULD INCLUDE SHERIDAN COUNTY WHICH
HAS BEEN HIT WITH QUITE A BIT OF RAIN RECENTLY. HAVE RAISED POPS
TO LIKELY ALONG THE BEARTOOTH FOOTHILLS AND EASTERN SLOPES OF THE
BIGHORNS. CANADIAN CLIPPER WILL ALLOW FOR COOLER AND DRIER SFC
RIDGE TO DROP INTO THE NORTHERN PLAINS INCLUDING OUR CWA BY FRI
NIGHT. EXPECT TEMPS IN THE LOWER TO MID 70S ON THU TO DROP INTO
THE 60S ON FRI WITH ANTICIPATED BACKDOOR COOLING.

FLAT RIDGING WILL BRING WARMER CONDITIONS TO OUR AREA NEXT SAT/SUN
AS ROCKIES LOW DEPARTS AND ANOTHER WEAK LOW REMAINS IN WESTERN
CANADA. WITH HIGH CONFIDENCE WOULD EXPECT A WARMING TREND NEXT
WEEKEND WITH A RETURN TO ABOVE NORMAL TEMPS. THERE IS STILL
POTENTIAL FOR WEAK SHORTWAVE ENERGY AND THUS SOME DIURNAL SHOWER
AND THUNDERSTORM ACTIVITY...ESPECIALLY CONSIDERING THE GROUND
MOISTURE IN PLACE.

BOTH THE GFS AND ECMWF SHOW SOME PREFRONTAL WARMING AHEAD OF NEXT
PACIFIC SHORTWAVE NEXT MON. THIS COULD BE OUR WARMEST DAY YET OF
2015...OBVIOUSLY WITH A LOT OF UNCERTAINTY THIS FAR IN ADVANCE...
BUT WILL PUSH EXPECTED HIGH TEMPS TO NEAR 80F WHICH IS CONSISTENT
WITH THE LATEST GUIDANCE. WILL ALSO KEEP CLIMO POPS FOR NEXT
MONDAY AS FLOW BACKS SOUTHWESTERLY AHEAD OF APPROACHING TROF.

JKL

&&

.AVIATION...

SHOWERS AND THUNDERSTORMS ARE DIMINISHING ACROSS THE AREA THIS
EVENING. ANOTHER DISTURBANCE IS STILL ON TAP TO IMPACT WESTERN
ZONES OVERNIGHT AND EARLY TUESDAY MORNING WITH A FEW SHOWERS.
SOME PATCHY FOG IS ALSO POSSIBLE EAST OF KBIL OVERNIGHT AND EARLY
TUESDAY MORNING...INCLUDING KMLS...KBHK...BROADUS...AND EKALAKA.
EXPECT SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE REGION
TUESDAY AFTERNOON AND EVENING. AAG

&&

.PRELIMINARY POINT TEMP/POPS...

    TUE     WED     THU     FRI     SAT     SUN     MON
-----------------------------------------------------------
BIL 048/072 050/073 050/070 050/066 048/076 052/078 053/080
    24/T    56/T    35/T    54/T    32/T    22/T    23/T
LVM 046/067 044/068 044/066 045/064 045/073 048/075 046/076
    36/T    66/T    55/T    54/T    43/T    32/T    23/T
HDN 048/075 049/076 049/074 049/068 045/077 050/079 049/082
    23/T    46/T    35/T    55/T    32/T    22/T    23/T
MLS 050/076 052/075 052/075 050/067 046/074 050/077 051/080
    22/T    36/T    43/T    33/T    22/T    21/B    23/T
4BQ 046/073 050/074 050/072 050/065 045/071 049/075 050/079
    22/T    36/T    44/T    44/T    31/B    11/B    23/T
BHK 045/073 047/073 048/073 046/064 039/067 044/074 048/077
    21/B    36/T    53/T    33/T    21/B    12/T    23/T
SHR 042/069 046/070 046/068 047/062 044/071 047/074 048/077
    23/T    55/T    46/T    65/T    42/T    22/T    23/T

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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