Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 250251
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
851 PM MDT SUN APR 24 2016

.UPDATE...
A SWATH OF RAIN AND SNOW HAS BEEN NEARLY STATIONARY THIS EVENING
FROM MUSSELSHELL S THRU EASTERN YELLOWSTONE S THROUGH BIG HORN
INTO SHERIDAN COUNTY. EARLIER REPORTS OF 1-2 INCHES OF SNOW ON
GRASSY SURFACES WERE RECEIVED FROM HARDIN. SOME ECHOES ALSO HAD
FORMED OVER WESTERN ZONES BUT WERE CURRENTLY WEAKENING. OTHER
SHOWERS NOTED OVER THE WESTERN DAKOTAS WERE DRIFTING W TOWARD THE
FORECAST AREA. SNOW CONTINUED OVER THE NE BIGHORNS WITH AROUND AN
INCH NOTED IN THE LAST SEVERAL HOURS AT A COUPLE OF SNOTELS. NEW
WRF CAME IN WITH A FAIRLY GOOD HANDLE ON THE CURRENT QPF AND THE
GRIDDED CONSSHORT HAD A GOOD HANDLE ON THE MAIN PRECIPITATION
SWATH OVER THE FORECAST AREA.

UPPER LOW WAS CENTERED NEAR SW SD ON WATER VAPOR IMAGERY THIS
EVENING AND MOISTURE WAS WRAPPING AROUND THE LOW INTO THE FORECAST
AREA CAUSING THE PRECIPITATION. 850 MB TEMPERATURES WERE -1 DEGREE
C AT KGGW AT 00Z MON AND WRF HAD THE ZERO LINE ENCOMPASSING THE
EASTERN HALF OF THE AREA THROUGH THE NIGHT. THE UPPER LOW WILL
PULL OFF TO THE E OVERNIGHT AND WILL RESULT IN PRECIPITATION
DECREASING. SO...ADJUSTED POPS TO FIT RADAR AND CONSSHORT TRENDS.
HAD 1 TO 2 INCHES OF SNOWFALL UNDER THE PRECIPITATION BAND. ISSUED
SPS EARLIER TO COVER THE SNOW AND POSSIBLE SLUSHY ROADS. WILL
LEAVE SNOW ADVISORY IN PLACE OVER THE NE BIGHORNS. MIDSHIFT WILL
LIKELY BE ABLE TO CANCEL IT.

NEXT UPPER LOW WILL REACH UT BY 00Z TUE. THIS LOW WILL BE PRETTY
FAR S TO HAVE A LARGE IMPACT ON THE FORECAST AREA. MAY NEED TO
LOWER POPS A BIT FOR MON. ARTHUR

&&

.SHORT TERM...VALID FOR MON AND TUE...
TWO UPPER LOWS IMPACTING THE WEATHER TONIGHT AND MONDAY ACROSS
THE REGION AS A COOL AND WET PATTERN WILL REMAIN IN PLACE. LOW 1
IS OVER WESTERN SOUTH DAKOTA THIS AFTERNOON AND IT IS PROGGED TO
MOVE EAST AND FILL DURING THE NEXT 24 HOURS. LOW 2 WILL DEVELOP
FROM A TROUGH MOVING INTO THE PACIFIC NORTHWEST THIS AFTERNOON AND
DEEPEN OVER THE GREAT BASIN. IN THE NEXT 24 HOURS THIS SUPPORTS
ADDITIONAL LIGHT PRECIPITATION ACROSS THE REGION THOUGH SOME
FAVORED AREAS FOR UPSLOPE COULD SEE BETTER AMOUNTS. THE BIG HORN
MOUNTAINS WILL CONTINUE TO SEE SOME SNOWFALL AS WILL THE FOOTHILLS
IN SHERIDAN COUNTY BUT EXPECT SNOWFALL TO BE LESS THAN FELL THIS
AFTERNOON. PRECIPITATION WILL FALL AS SNOW IN SOME AREAS OF THE
PLAINS AS TEMPERATURES ARE VERY COOL THIS AFTERNOON BUT EXPECT
ACCUMULATIONS LESS THAN AN INCH. ADDITIONAL HEAVY RAIN IS NOT
EXPECTED. FOR MONDAY THIS TRANSLATE TO A COOL AND CLOUDY DAY WITH
RAIN SHOWERS PRODUCING LIGHT PRECIPITATION.

LOW 2 SPINS UP OVER NORTHEAST COLORADO MONDAY NIGHT INTO TUESDAY
AND IT HAS TRENDED SOUTHWARD COMPARED TO PREVIOUS MODEL RUNS. THIS
MEANS THE COOL AND CLOUDY WEATHER WILL CONTINUE WITH PRECIPITATION
BUT ACCUMULATIONS WILL BE FAIRLY LIGHT FOR MOST AREAS. EXCEPTION
IS SOUTHEAST MONTANA WHERE WRAP AROUND PRECIPITATION WILL BE
HEAVIER...BUT THIS IS CONTINGENT ON THE MOISTURE NOT BEING
SIPHONED OFF BY THUNDERSTORMS OVER THE PLAINS. TEMPERATURES LOOK A
BIT WARMER SO DO NOT EXPECT MUCH SNOW OVER THE PLAINS AND QPF
AMOUNTS FOR THE MOUNTAINS ARE NOT GOING TO BE SIGNIFICANT WITH THE
CURRENT TRACK OF THIS SYSTEM. BORSUM


.LONG TERM...VALID FOR WED...THU...FRI...SAT...SUN...
THE EXTENDED PERIOD SHOULD BEGIN WITH BROAD TROUGHING OVER THE
WESTERN CONUS. THIS WILL YIELD MOSTLY COOL AND CLOUDY CONDITIONS
ACROSS THE FORECAST AREA. WEDNESDAY LOOKS LIKE ANOTHER WET DAY IS
IN THE FORECAST AS A DISTURBANCE IN THE MAIN TROUGH CLOSES OFF
OVER WESTERN NEBRASKA AND SOUTH DAKOTA. SIMILAR TO THIS WEEKENDS
EVENT...THIS WILL BRING GOOD MOISTURE TRANSPORT AND LIFT ALONG
WITH PLENTY OF SHOWERS TO EASTERN AND CENTRAL MONTANA. THIS LOW
APPEARS THAT IT WILL CUT OFF AND SLOWLY FILL IN OVER THE DAY
WEDNESDAY. THIS SHOULD HELP GIVE CENTRAL AND WESTERN ZONES BETTER
PRECIPITATION CHANCES WEDNESDAY NIGHT INTO THURSDAY AS THE
MOISTURE IS ADVECTED WESTWARD.

ENSEMBLE SOLUTIONS SUGGEST ANOTHER DISTURBANCE WILL PUSH THROUGH
THE MAIN TROUGH ON THURSDAY. THIS DISTURBANCE APPEARS TO DIG A
LITTLE FURTHER SOUTH THAN THE LAST FEW SO DID NOT GET TOO SPECIFIC
WITH POPS AND PUT 20 TO 50 POPS ACROSS MUCH OF THE REGION THURSDAY
AND FRIDAY...THOUGH THESE MIGHT NEED TO BE TONED DOWNED IN LATER
UPDATES AS MORE AGREEMENT IN THE EVENTUAL STORM PATH COMES ABOUT.

BEYOND FRIDAY THERE IS QUITE A BIT OF UNCERTAINTY IN THE
EVOLUTION OF THIS DIGGING TROUGH. IF THE DISTURBANCE CAN LIFT
NORTH AGAIN AS IT DECAYS...PRECIPITATION CHANCES WILL BE BETTER
FOR US LATE IN THE WEEK...OTHERWISE CONDITIONS WILL BE WARMER AND
DRIER WITH MORE SPOTTY CHANCES FOR PRECIPITATION ON FRIDAY AND
SATURDAY.

TEMPERATURES WILL BE IN THE MID TO UPPER 40S THROUGH THE
WEEK...BUT WARMER CONDITIONS IN THE MID TO UPPER 50S ARE POSSIBLE
BY WEEKS END. THOUGH WARMER CONDITIONS DEPEND ON THE TRACK OF THE
DIGGING DISTURBANCE IN THE LATE WEEK. DOBBS

&&

.AVIATION...
MVFR TO IFR CONDITIONS DUE TO CEILINGS WILL BE PREVALENT AROUND
THE AREA TONIGHT EVEN AS PRECIPITATION DECREASES. SOME FOG WILL BE
POSSIBLE EAST OF KBIL...BUT AS CLOUDS STICK AROUND...VISIBILITY
SHOULD NOT GO MUCH BELOW 3 MILES. MOUNTAINS WILL BE OBSCURED. TWH
&&

.PRELIMINARY POINT TEMP/POPS...

    MON     TUE     WED     THU     FRI     SAT     SUN
-----------------------------------------------------------
BIL 036/046 037/047 037/048 036/048 036/055 039/058 040/058
    55/W    66/W    55/W    44/W    33/W    23/W    33/W
LVM 037/052 035/049 034/052 034/049 033/054 035/057 036/057
    36/W    66/W    43/W    44/W    33/W    33/W    33/W
HDN 035/047 035/047 035/049 033/049 034/055 036/058 036/058
    95/W    66/W    55/W    43/W    33/W    33/W    32/W
MLS 034/046 035/047 035/047 033/049 035/054 038/056 038/059
    44/W    44/W    66/W    43/W    22/W    23/W    22/W
4BQ 034/048 035/045 034/045 032/047 032/052 035/055 035/056
    34/W    57/W    75/W    43/W    23/W    33/W    33/W
BHK 034/043 031/045 032/044 029/044 031/049 033/052 034/056
    35/W    34/W    66/W    43/W    22/W    33/W    23/W
SHR 033/049 035/045 033/046 032/047 032/052 034/054 035/054
    94/W    77/W    65/W    44/W    33/W    34/W    33/W

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...WINTER WEATHER ADVISORY IN EFFECT UNTIL 6 AM MDT MONDAY FOR
      ZONE 98.

&&

$$
WEATHER.GOV/BILLINGS



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