Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 162111
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
311 PM MDT WED APR 16 2014

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

UNSTABLE NORTHWEST FLOW WILL REMAIN OVER THE AREA TONIGHT. LIFT
WILL BE PROVIDED BY STEEP LAPSE RATES/JET DYNAMICS AND 500 MB
VORTICITY MOVING THROUGH. THIS WILL BRING SCATTERED RAIN AND SNOW
SHOWERS OVERNIGHT. PRECIPITATION WILL END OVER THE WEST AND
CENTRAL ZONES THURSDAY MORNING AS STRONG SUBSIDENCE WILL BE OVER
THESE AREAS WITH A RIDGE OF HIGH PRESSURE BUILDING IN. A FEW
ISOLATE SHOWERS WILL CONTINUE OVER THE EASTERN ZONES BUT ONLY
LIGHT QPF AMOUNTS ARE EXPECTED. DID RAISE TEMPERATURES A FEW
DEGREES TOMORROW BUT CLOUD COVER WILL LIMIT FULL HEATING. THE
RIDGE WILL BRING DRY WEATHER OVERNIGHT BUT ANOTHER TROUGH MOVING
ACROSS SOUTHERN CANADA WILL BEGIN IMPACTING OUR FORECAST AREA ON
FRIDAY. THE MAIN LIFT WITH THIS TROUGH WILL REMAIN NORTH OF US BUT
A PACIFIC COLD FRONT WILL BE DRAGGED ACROSS OUR AREA. STRONG
SURFACE CONVERGENCE ALONG THE FRONT WILL BRING SCATTERED SHOWERS.
NAM12 IS BRINGING IN SURFACE BASED CAPES OF 500 J/KG ALONG WITH
LI`S OF A -2C ACROSS EXTREME SOUTHERN POWDER RIVER AND CARTER
COUNTIES. HAVE LEFT OUT THE MENTION OF THUNDER AT THIS TIME AS
BUFKIT SHOWING THESE AREAS TO BE CAPPED DUE TO STRONG SOUTHEAST
WINDS. RICHMOND


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

MODELS WERE IN GOOD AGREEMENT IN SHOWING A MAINLY DRY AND WARM
PERIOD SAT THROUGH MON AS RIDGING MOVES ACROSS THE AREA.

A STRONG PACIFIC UPPER LOW WILL THEN APPROACH THE PACIFIC NW MON
NIGHT THROUGH TUE AND ROTATE INTO THE REGION TUE NIGHT THROUGH
WED. OVER THE PAST FEW RUNS...THE GFS HAS TRENDED N WITH THE UPPER
LOW...AND BY 00Z THU HAD IT OVER MT IN THE LATEST RUN. MEANWHILE
THE ECMWF TRENDED THE LOW NE INTO E MT AND DEEPENED IT BY 00Z THU.
THE NORMALIZED STANDARD DEVIATION FOR BOTH MODELS SHOWED
CONFIDENCE ON THE LOWER SIDE OF NEUTRAL WITH THE UPPER LOW
FORECAST FOR WED. BOTH MODELS FORECAST AN UPPER LOW MOVING INTO
THE REGION...BUT THE STRENGTH AND POSITION OF THE SYSTEM WAS
UNCERTAIN. IN ADDITION...THE NAEFS TABLE SHOWED INCREASING
ANOMALIES OF SPECIFIC HUMIDITY FROM TUE THROUGH WED SUGGESTING
PLENTY OF MOISTURE WILL BE AVAILABLE FOR THIS SYSTEM.

PRECIPITATION WILL START MOVING INTO THE WESTERN ZONES MON NIGHT
AND REMAIN MAINLY OVER THE W ON TUE. DID INCREASE POPS FROM KBIL W
ON TUE. MODELS AGREED IN SPREADING THE PRECIPITATION FURTHER E TUE
NIGHT SO HAVE ADJUSTED POPS. DESPITE DIFFERENCES IN THE LOW
TRACK...MODELS HAD A GOOD CHANCE OF RAIN OVER MUCH OF THE AREA ON
WED SO INCREASED POPS ACROSS THE AREA. ALSO ADDED THUNDER TO THE
WARM SECTOR BASED ON THE GFS. DUE TO THE INCREASED
PRECIPITATION...HAVE LOWERED TEMPERATURES ACROSS MOST OF THE AREA
ON WED. THIS SYSTEM WILL NEED TO BE WATCHED CLOSELY AS RAIN ON
MOUNTAIN SNOWPACK COULD CREATE FLOODING ISSUES. LATEST CIPS
ANALOGS SHOWED 1 TO 1.25 INCHES OF PRECIPITATION WITH SIMILAR
SYSTEMS. THE LATEST GFS AND ECMWF DO TAKE THE HIGHEST
PRECIPITATION AMOUNTS MAINLY TO THE NW OF THE FORECAST AREA ON
WED. ARTHUR
&&

.AVIATION...

RAIN AND SNOW SHOWERS WILL BE LIKELY FROM AROUND KBIL W THIS
EVENING WITH MVFR AND LOCALIZED IFR CONDITIONS. EXPECT ISOLATED TO
SCATTERED RAIN AND SNOW SHOWERS E OF KBIL AND OVER KSHR. ISOLATED
TO SCATTERED SNOW SHOWERS WILL OCCUR OVERNIGHT WITH MVFR TO IFR
CONDITIONS. AREAS OF MOUNTAIN OBSCURATION WILL CONTINUE TONIGHT.
EXPECT WIDELY SCATTERED RAIN AND SNOW SHOWERS E OF KBIL ON THU
WITH MVFR TO IFR CONDITIONS. THERE WILL BE LOCALIZED MOUNTAIN
OBSCURATION. ARTHUR

&&

.PRELIMINARY POINT TEMP/POPS...

    THU     FRI     SAT     SUN     MON     TUE     WED
-----------------------------------------------------------
BIL 031/061 039/065 040/066 041/072 040/069 043/069 045/052
    61/E    12/W    20/B    00/U    00/B    23/T    45/W
LVM 028/061 039/061 036/066 039/068 038/066 041/065 039/052
    61/N    23/W    20/U    00/U    02/W    24/T    45/W
HDN 028/061 034/066 037/067 040/073 041/072 039/072 041/055
    61/E    12/W    30/B    00/U    00/U    12/W    35/W
MLS 029/059 034/063 036/065 040/072 041/070 041/073 043/058
    33/W    12/W    30/U    00/U    00/U    12/W    34/T
4BQ 026/059 033/066 037/066 041/073 040/073 042/075 044/062
    22/W    12/W    30/B    00/U    00/U    12/W    24/T
BHK 026/052 029/058 033/063 036/071 039/069 040/071 043/061
    23/W    12/W    30/B    00/U    00/U    12/W    24/T
SHR 028/059 036/067 037/064 037/070 038/069 040/071 042/058
    41/E    12/W    20/B    00/U    00/U    02/W    24/T

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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