Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 190240
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
840 PM MDT FRI APR 18 2014

.UPDATE...
MINOR UPDATES TO THE FORECAST TONIGHT AS THE THUNDERSTORM THREAT
HAS ENDED ACROSS THE FORECAST AREA...BUT SOME SHOWERS WILL LINGER
ACROSS EASTERN MONTANA AND ACROSS THE BEARTOOTH MOUNTAINS THIS
EVENING. INSTABILITY ACROSS EASTERN MONTANA HAS WANED WITH SUNSET
AND THE FRONT MOVING INTO MORE STABLE AIR...THUS REMOVED MENTION
OF THUNDER FROM THE FORECAST. AREA OF SHOWERS WILL CONTINUE TO
SLIDE EAST THIS EVENING AS THE PARENT WAVE SLIDES EAST ACROSS
NORTHERN MONTANA. EXPECT SHOWER ACTIVITY TO DIMINISH BY
MIDNIGHT...ALONG WITH DECREASING WINDS OVERNIGHT.

CHURCH

&&

.SHORT TERM...VALID FOR SAT AND SUN...

SURFACE FRONT HAS PASSED THROUGH MUCH OF THE REGION...BRINGING
WEST WINDS AND SCATTERED SHOWERS ACROSS THE REGION. THE UPPER
LEVEL TROF IS LAGGING BEHIND A BIT...AND APPEARS TO BE BRINGING
PRESSURE FALLS IN THE REGION TO COINCIDE WITH EXPECTED PERIOD OF
CLEARING THIS AFTERNOON. THIS SHOULD MITIGATE ANTICIPATED
DOWNSLOPE FLOW AT LEAST AS IT IMPACTS AREAS OFF THE FOOTHILLS
AREAS. THIS TIMING ALSO COMBINES WELL WITH THE PERIOD OF IMPROVED
MID LEVEL INSTABILITY...AND UPPER LEVEL JET SUPPORT THROUGH THE
AFTERNOON AND EVENING. FINALLY THE SECONDARY WAVE IS EXPECTED TO
SWING THROUGH THE REGION LATER THIS EVENING...WHICH SHOULD SCOUR
OUT REMAINING MOISTURE IN WEST...BUT MAY ADD A BOOST TO ANY
THUNDERSTORM POTENTIAL FURTHER EAST THIS EVENING. AS A RESULT HAVE
INTRODUCED POPS FOR THIS EVENING PERIOD WEST THROUGH
BILLINGS...AND EXPANDED AREA OF ISOLATED THUNDERSTORMS FROM
BILLINGS EASTWARD. CLEARING FOLLOWING UPPER LEVEL DISTURBANCE
SHOULD RESULT IN SIGNIFICANT COOLING OVERNIGHT...WITH BREEZY
CONDITIONS PERSISTING OVERNIGHT.

WEAK UPPER LEVEL RIDGING DEVELOPS FOR SATURDAY...BRINGING WARM
AND DRY CONDITIONS TO THE REGION FOR SATURDAY. WINDS WILL CONTINUE
TO TAPER OFF THROUGH THE DAY...SO SHOULD BE A VERY NICE SPRING DAY
WITH THE EXCEPTION OF A COOL START.

ANOTHER DISTURBANCE WILL MOVE ACROSS THE REGION SUNDAY MORNING.
BEST ENERGY IS PROGGED TO STAY NORTH OF THE FORECAST AREA. GFS IS
POINTING AT THE PRECIP EXTENDING INTO AT LEAST THE NORTHERN
PORTIONS OF THE CWA. HAVE INTRODUCED SLIGHT POPS FOR SATURDAY
NIGHT/SUNDAY MORNING...IN LARGE PART BASED ON MODELS TRENDING
PRECIP FURTHER SOUTH WITH EACH RUN. RELATIVE QUICK MOTION OF THE
SYSTEM SHOULD STILL ALLOW TEMPERATURES TO CLIMB INTO 60S AND
70S.

WARM DAYTIME TEMPERATURES WILL BEGIN TO MELT MID LEVEL MOUNTAIN
SNOW...BRINGING RISING WATER AND INCREASED STREAM FLOW TO AREA
RIVERS IND STREAMS. HOWEVER...CONTINUED COOL OVERNIGHT TEMPS
SHOULD HELP TO SLOW THAT MELT SOME. AAG

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

ACTIVE WEATHER STILL ANTICIPATED NEXT WEEK...BUT LATEST MODEL
TRENDS ARE AWAY FROM A SIGNIFICANT PRECIPITATION EVENT. PLENTY OF
UNCERTAINTY STILL EXISTS IN TRACK OF MID LEVEL LOW HOWEVER.

MONDAY WILL BE DRY WITH SEASONABLY WARM TEMPS...MAINLY 60S TO NEAR
70...WITH RIDGE AXIS JUST TO OUR WEST SUPPORTIVE OF EASTERLY SFC
FLOW. COULD SEE A LITTLE WEAK CONVECTION OVER OUR WESTERN MTNS AND
FOOTHILLS BY EVENING AS PRESSURES BEGIN TO FALL AND MID LEVEL
MOISTURE INCREASES OUT OF THE GREAT BASIN...BUT BETTER CHANCES OF
PCPN SHOULD HOLD OFF UNTIL LATER TUESDAY.

AMPLIFIED LOW OFF THE PACIFIC COAST IS A LITTLE SLOWER TO MOVE
INLAND PER LATEST MODEL TRENDS...SO HAVE PUSHED BACK POPS A BIT IN
THE MONDAY/TUESDAY PERIOD. DOOR OPENS TO STRONGER DYNAMICS FROM
THE SW BY LATE TUESDAY. THIS ENERGY ALONG WITH SPRING-LIKE
MOISTURE ADVECTION UP THE HIGH PLAINS WILL YIELD AT LEAST A THREAT
OF THUNDERSTORM ACTIVITY IN OUR SOUTH AND WEST. TUESDAY WILL ALSO
BE A WARM DAY WITH THERMAL LOW IN SE MT...AND PERHAPS THE WARMEST
YET OF 2014 FOR SOME LOCATIONS...WITH WIDESPREAD HIGHS IN THE 70S.
THIS WILL ADD TO THE INSTABILITY. WILL KEEP HIGHEST POPS PAINTED
IN OUR WEST TUESDAY NIGHT PER INTERACTION BETWEEN GREAT BASIN
SHORTWAVE AND MID LEVEL BAROCLINICITY. IT SHOULD ALSO BE NOTED
THAT FREEZING LEVELS WILL FALL RAPIDLY IN OUR WEST LATE TUESDAY
NIGHT INTO EARLY WEDNESDAY...SO EXPECT MOUNTAIN RAIN SHOWERS TO
TURN TO SNOW.

MODELS STILL SCATTERED IN THEIR HANDLING OF THE UPPER LOW AS IT
MOVES THROUGH THE NORTHERN ROCKIES AND INTO THE PLAINS...BUT THERE
ARE A FEW THINGS WE CAN HAVE INCREASED CONFIDENCE IN. FIRST...WE
ARE NOT LOOKING AT A CUT OFF LOW TO OUR SOUTH WHICH WOULD BRING US
A PROLONGED PERIOD OF PCPN. MID LEVEL LOW WILL PUSH TO OUR NORTH
AND THIS WILL ALLOW FOR DOWNSLOPING AND DRIER AIR...THOUGH WITH
SOME SHOWER ACTIVITY UNDER THE COLD AIR ALOFT AND CYCLONIC FLOW.
SECOND...PCPN OVER THE HIGH TERRAIN WEDNESDAY AND THURSDAY WILL BE
IN THE FORM OF SNOW...PER 700MB TEMPS FALLING TO NEAR -8C. SO
ALTHOUGH WE COULD BE LOOKING AT SOME SNOW ACCUMULATION IN THE
MTNS...THIS WILL NOT BE A PROLONGED RAIN ON SNOW EVENT. LASTLY...
LATEST MODEL TRENDS SUGGEST AT LEAST THE POSSIBILITY OF A TROWAL
WRAPPING BACK INTO OUR CWA ON THE BACK SIDE OF THE LOW AS IT MOVES
INTO THE NORTHERN PLAINS BY THURSDAY INTO FRIDAY. SO COULD SEE
SOME COLD RAIN IN OUR CENTRAL AND EAST PARTS AS THIS HAPPENS...
WITH WET SNOW EVEN POSSIBLE OVER THE HILLS AS 850MB TEMPS FALL TO
NEAR ZERO. HAVE MADE SOME MINOR ADJUSTMENTS TO POPS TO SHOW
HIGHER PROBABILITIES IN OUR EAST BY DAYS 7/8...BUT OTHERWISE KEPT
THEM BROADBRUSHED AND ABOVE CLIMATOLOGY GIVEN UNCERTAINTY IN EXACT
TRACK OF THE LOW.

AS FOR TEMPERATURES...WARMEST DAYS WILL OF COURSE BE MONDAY AND
TUESDAY...WITH A DOWNWARD TREND EXPECTED THEREAFTER. IF TROWAL
DOES IMPACT US WE COULD SEE HIGHS ONLY IN THE 40S BY THURSDAY.
FRIDAY WILL REMAIN COOL EVEN AS PCPN CHANCES BEGIN TO LESSEN...AS
CANADIAN SFC HIGH SETTLES IN.

JKL
&&

.AVIATION...

SCATTERED SHOWERS WILL MOVE OVER EASTERN MONTANA THIS EVENING.
BRIEF MODERATE RAIN AND WIND GUSTS TO 35KTS ARE POSSIBLE WITH
THESE SHOWERS. THE SHOWERS WILL BE CONFINED TO EASTERN MONTANA AND
IMPACT KMLS THROUGH 04Z AND KBHK THROUGH 06Z. CONDITIONS WILL
LOWER TO MVFR BRIEFLY IN THE STRONGER CELLS...OTHERWISE VFR
CONDITIONS ARE EXPECTED. THE REST OF THE AREA WILL BE DRY THE REST
OF THE NIGHT. GUSTY NORTHWEST WINDS WILL GRADUALLY DECREASE THIS
EVENING AND OVERNIGHT. MOUNTAINS WILL BE OCCASIONALLY OBSCURED
THIS EVENING BUT BECOME LESS OBSCURED OVERNIGHT AS CLOUDS
DECREASE. MOSTLY CLEAR SKIES ARE EXPECTED SATURDAY. TWH
&&

.PRELIMINARY POINT TEMP/POPS...

    SAT     SUN     MON     TUE     WED     THU     FRI
-----------------------------------------------------------
BIL 036/067 042/068 037/069 044/072 046/057 038/050 032/051
    10/U    12/W    00/U    12/T    45/W    44/W    32/W
LVM 033/065 038/066 035/070 041/071 039/053 033/052 030/057
    10/U    21/U    00/B    25/T    66/W    43/W    32/W
HDN 035/068 038/070 034/070 039/075 041/058 034/051 031/053
    30/U    11/U    00/U    12/T    45/W    44/W    32/W
MLS 036/066 039/072 037/067 040/071 044/061 036/050 030/049
    60/U    12/W    00/U    01/B    35/T    45/W    42/W
4BQ 036/067 039/073 037/069 042/075 044/062 033/052 030/050
    30/U    11/U    00/U    12/T    25/T    45/W    42/W
BHK 035/063 037/071 036/065 039/067 044/063 034/047 026/046
    50/U    12/W    00/U    01/N    35/T    45/W    42/W
SHR 034/066 037/070 034/069 039/076 042/058 037/050 031/051
    30/U    11/U    00/U    02/T    34/W    44/W    32/W

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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