Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 012102
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
302 PM MDT WED APR 1 2015

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

WELL-MIXED W-NW WINDS GUSTING FROM 30-45 MPH ACROSS THE CWA THIS
AFTERNOON. WE HAVE TAPPED INTO DRY MID LEVEL AIR AND DEWPTS HAVE
FALLEN TO THE SINGLE DIGITS TO MID TEENS...YIELDING RHS IN THE
TEENS IN PLACES. WILL MAKE NO CHANGES TO THE RED FLAG WARNING THAT
RUNS TIL 9 PM THIS EVENING.

LIFTED INDICES NEAR ZERO EXIST THIS AFTERNOON AND CU FIELDS ARE
DEVELOPING. WILL SEE PERIODS OF SNOW SHOWERS OVER THE MTNS BUT LOW
LEVELS SHOULD REMAIN MOSTLY DRY LATE THIS AFTN AND EVENING PER
THE VERY DRY SUB-CLOUD AIR AND STRONG DOWNSLOPE WINDS. COULD SEE
A FEW SPRINKLES THOUGH.

WEAK ENERGY FROM THE NW WILL MOVE ACROSS THE REGION TOMORROW.
INSTABILITY WILL EXIST UNDER COLD POOL ALOFT IN OUR WEST...WITH
500MB TEMPS TO -33C AND LIFTED INDICES AGAIN NEAR ZERO OR -1C.
GREATEST CHANCE OF MAINLY AFTERNOON AND EVENING RAIN/SNOW SHOWERS
WILL BE WEST OF BILLINGS PER CONVERGENT BOUNDARY LAYER FLOW IN
THIS REGION...WITH SOME BANDING POSSIBLE DOWNWIND OF MOUNTAINS.
TEMPS WILL RISE INTO THE 40S BUT WITH WET BULB ZERO HEIGHTS NEAR
THE GROUND...SO EXPECT PCPN TYPE TO BE MIXED. CONVERGENT NORTH
FLOW MAY ACTUALLY BRING A LITTLE WET SNOW ACCUMULATION TO THE
FOOTHILLS NEAR ROSCOE AND RED LODGE...WITH A COUPLE INCHES OVER
THE MTNS. SYNOPTIC FORCING WILL BE VERY WEAK SO SHOWER ACTIVITY
WILL BE DRIVEN PRIMARILY BY INSTABILITY AND OROGRAPHICS. WITH
THIS IN MIND HAVE RAISED POPS A BIT IN NORTH FLOW FAVORED AREAS.

PV MAX WILL MOVE ACROSS EASTERN MT LATE THURSDAY NIGHT THROUGH
MIDDAY FRIDAY AS HEIGHTS BEGIN TO BUILD FROM THE WEST. WILL
SUSTAIN A SLIGHT POP ALONG THIS WEAK ENERGY IN OUR EAST ON
FRIDAY...AGAIN WITH LIFTED INDICES NEAR ZERO ALONG THIS AXIS.
OTHERWISE WE SHOULD SEE DRYING FRIDAY AFTERNOON AND NIGHT AS WE
TRANSITION TO WEAK RIDGING/ANTICYCLONIC FLOW ALOFT.

THURSDAY WILL BE COOLER THAN TODAY AS WE COLD ADVECT BEGINNING
LATER TONIGHT...AND WE WILL WELCOME NEGATIVE 850MB TEMPS INTO OUR
EAST HALF. MIXING WILL REMAIN FAIRLY DEEP AND WE WILL MAKE THE
MOST OUT OF THIS CHILLIER AIRMASS. LOOK FOR HIGHS IN THE 40S TO
NEAR 50 DEGREES TOMORROW. WARMING TREND BEGINS FRIDAY WITH ONSET
OF RIDGING AND SHOULD SEE HIGHS INTO THE 50S. NEXT COUPLE OF
NIGHTS WILL BE CHILLIER THAN WE HAVE SEEN IN AWHILE AND SOME
LOCATIONS WILL SEE TEMPS FALL BELOW FREEZING.

JKL

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

THE PATTERN WAS CERTAINLY SHIFTING TO A COOLER ONE COMPARED TO
WHAT THE AREA HAS EXPERIENCED LATELY. NOT A GREAT SIGNAL OUT THERE
FOR A WET EVENT IN THE NEAR FUTURE...BUT THE PATTERN CHANGE
CERTAINLY PROVIDES OPPORTUNITIES FOR SHOWERS HERE AND THERE.

SATURDAY LOOKS TO BE THE DRIEST DAY OF THE EXTENDED PERIOD WITH A
FLAT UPPER RIDGE IN PLACE. AN UPPER TROUGH MOVES INTO THE WEST AND
ADVANCES INTO THE GREAT BASIN FOR SUNDAY THROUGH MONDAY. MODELS
ARE NOT VERY CONSISTENT WITH THIS FEATURE AS THE GFS WAS SHARPER
WITH THE ENERGY KICKING OUT OF THE TROUGH EARLY MONDAY...BUT LOWER
HEIGHTS AND CYCLONIC FLOW WOULD LEAD TO AN INCREASED CHANCE OF
SHOWERS. MAIN JET FORCING DOES SLIDE TO THE NORTH...SO WILL NOT
RAISE POPS PAST THE SCATTERED CATEGORY.

SOME SORT OF DIRTY RIDGING WILL BRIEFLY TAKE OVER ON TUESDAY AS
THE NEXT UPSTREAM TROUGH DROPS INTO OREGON. MODELS DIVERGE GREATLY
WITH THIS FEATURE AS THE GFS WAS STRONGER AND MUCH MORE ORGANIZED
WITH THE UPPER LOW AS IT DROPS INTO NORTHERN UTAH EARLY WEDNESDAY.
THE GFS DOES HINT AS SECONDARY CIRCULATION SETTING UP OVER
NORTHERN WYOMING WEDNESDAY AFTERNOON...WHICH WOULD BE IN A VERY
GOOD POSITION FOR PRECIPITATION CHANCES. THE ECMWF HINTS AT THE
LOW SHIFTING INTO NORTHEAST WYOMING WITH THE STRONGEST FORCING
CENTERED OVER SOUTHEAST MONTANA. NEED TO GIVE THIS SOME TIME TO
SEE HOW THE MODELS RESOLVE IT...BUT THE THOUGHT OF A CHANCE OF
SOME PRECIPITATION AND COOLER WEATHER CONTINUING INTO MID WEEK
LOOKS ON TARGET. TWH

&&

.AVIATION...

GUSTY W-NW WINDS WILL CONTINUE THROUGH SUNSET...WITH GUSTS OF 25-
35 KTS BEING COMMON. GUSTINESS OF WINDS WILL DECREASE TONIGHT
THOUGH WITH SPEEDS REMAINING IN THE 15-25 KTS RANGE. WINDS WILL
INCREASE ESPECIALLY IN OUR EAST ON THURSDAY WITH GUSTS OF 25-35
KTS NEAR KMLS AND KBHK. OTHERWISE...VFR CONDITIONS WILL PREVAIL
WITH SCATTERED TO BROKEN MID AND HIGH CLOUDS. THE MOUNTAINS WILL
BE OCCASIONALLY OBSCURED IN SNOW SHOWERS. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    THU     FRI     SAT     SUN     MON     TUE     WED
-----------------------------------------------------------
BIL 034/050 031/057 035/064 034/060 035/054 030/052 032/055
    12/W    21/B    00/B    00/B    33/W    32/W    22/W
LVM 028/045 026/053 031/058 028/055 030/050 026/053 026/055
    24/W    30/B    01/B    13/W    34/W    32/W    32/W
HDN 031/051 028/059 030/067 033/064 034/056 026/054 029/058
    12/W    21/B    00/B    00/B    33/W    32/W    22/W
MLS 032/049 027/056 030/064 032/061 033/051 028/048 029/052
    02/W    12/W    00/B    01/B    34/W    32/W    12/W
4BQ 031/048 023/055 028/066 031/063 032/058 026/052 030/055
    02/W    12/W    00/B    00/B    23/W    32/W    22/W
BHK 030/044 022/054 026/063 028/058 028/046 022/043 025/049
    02/W    02/W    00/B    01/B    33/W    42/W    12/W
SHR 029/046 025/053 026/063 029/061 032/054 025/051 027/053
    12/W    21/B    00/B    01/B    23/W    32/W    22/W

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...RED FLAG WARNING IN EFFECT UNTIL 9 PM MDT THIS EVENING FOR
      ZONES 28>42-56>58-63>68.
WY...RED FLAG WARNING IN EFFECT UNTIL 9 PM MDT THIS EVENING FOR
      ZONES 98-99.

&&

$$
WEATHER.GOV/BILLINGS


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