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000
FXUS65 KBYZ 171454
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
854 AM MDT MON JUN 17 2013

.UPDATE...
JUST A FEW CHANGES FOR THE MORNING UPDATE. VISIBLE SATELLITE
DEPICTED CLOUDS MOVING E OUT OF THE EASTERN PART OF THE FORECAST
AREA THIS MORNING. THE CLOUDS WERE ASSOCIATED WITH A SHORTWAVE
ROTATING OUT OF NE MT AND THE TAIL END OF A JET. WEAK ENERGY WILL
MOVE INTO THE REGION THIS AFTERNOON TRIGGERING THE DEVELOPMENT OF
THUNDERSTORMS OVER THE MOUNTAINS. JET ENERGY OVER E MT/SD WILL
CREATE CONVECTION OVER THE BLACK HILLS WHICH THE MODELS SUGGESTED
COULD MOVE INTO SE MT. AFTERNOON POPS REFLECTED THE SITUATION WELL
EXCEPT HAVE PAIRED BACK POPS FURTHER TO THE W TO TAKE OUT KBIL AND
NEARBY AREAS. BUFKIT SOUNDINGS HAD A LOT OF CONVECTIVE INHIBITION
AWAY FROM THE MOUNTAINS THIS AFTERNOON SO PRECIPITATION SHOULD BE
CONFINED TO AREAS OVER AND NEAR THE MOUNTAINS. LATE MORNING
CONVECTION WAS POSSIBLE OVER AND NEAR THE NE BIG HORNS BASED ON
MODEL QPF AND WEAK SHORTWAVE ENERGY. OTHERWISE GFS AND WRF WERE
OVERDONE IN THEIR QPF ALONG THE MT/WY BORDER THIS MORNING. HRRR
WAS HANDLING THE SITUATION BETTER THIS MORNING THAN THE OTHER
MODELS...BUT KEPT THE FORECAST AREA PRECIPITATION-FREE THROUGH THE
DAY. GIVEN THE APPROACH OF THE SHORTWAVES AND ELEVATED
CAPE...MOUNTAINS SHOULD AT LEAST GET SOME CONVECTION. WILL WAIT TO
SEE HOW THE AFTERNOON DEVELOPS BEFORE MAKING ANY EVENING POPS
ADJUSTMENTS. TEMPERATURES WERE ON TRACK WITH MIXING BETWEEN 850 MB
AND 700 MB. ADJUSTED WINDS TO FIT LATEST TRENDS BETTER. ARTHUR

&&

.SHORT TERM...VALID FOR TDY AND TUE...

THE WEATHER PATTERN WILL SLOWLY GROW MORE UNSETTLED FOR TODAY AND
TOMORROW AS EASTERLY SURFACE FLOW BECOMES ESTABLISHED UNDER
RIDGING ALOFT AND A PACIFIC LOW SLOWLY APPROACHES THE FORECAST
AREA. YESTERDAY SAW AN INCREASE IN CONVECTION OVER OUR SOUTHERN
MOUNTAIN LOCATIONS AND INTO WYOMING. FOR TODAY...THE INCREASING
EASTERLY TO SOUTHEASTERLY LOW-LEVEL FLOW WILL ACT TO INCREASE AND
DEEPEN LOW-LEVEL MOISTURE ACROSS THE PLAINS OF THE FORECAST AREA.
WITH SIMILAR MOISTURE AND DIURNAL HEATING OVER THE MOUNTAINS TODAY
AS YESTERDAY...EXPECT TO SEE ANOTHER ROUND OF AFTERNOON CONVECTION
DEVELOP OVER THE MOUNTAIN LOCATIONS. TODAY...HOWEVER...EXPECT THAT
THE SLOWLY INCREASING MOISTURE OVER THE PLAINS WILL ALLOW SOME OF
THE STRONGER SHOWERS/THUNDERSTORMS TO TRACK FARTHER OFF THE
MOUNTAINS BEFORE THE CAPPING BECOMES TO STRONG FOR THEM. THUS FOR
TODAY...HAVE INCREASED POPS OVER THE FOOTHILLS LOCATIONS AND
NEARBY PLAINS TO SHOW ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS FOR LATER IN THE AFTERNOON INTO THE EARLY EVENING.

FOR TUESDAY...PERSISTENT LOW-LEVEL EASTERLY FLOW WILL CONTINUE
INCREASE LOW-LEVEL MOISTURE. A WEAK DISTURBANCE UNDERCUTTING
THE RIDGE IN THE SOUTHWESTERLY FLOW ALOFT WILL AID IN ENHANCING
SHOWERS AND THUNDERSTORMS OVER THE MOUNTAINS TUESDAY AFTERNOON
BEFORE THEY TRACK OFF THE MOUNTAINS TO THE NORTH ACROSS THE NEARBY
FOOTHILLS AND PLAINS. ANOTHER ROUND OF CONVECTION IS EXPECTED TO
DEVELOP OVER EASTERN WYOMING AND COULD IMPACT FAR SOUTHEASTERN
MONTANA AS IT PUSHED OUT INTO SOUTH DAKOTA BY THE EVENING. THUS
FOR TUESDAY...HAVE INCREASED POPS TO SCATTERED OVER THE MOUNTAINS
AND THE CORRIDOR FROM LIVINGSTON TO HARLOWTON TO JUDITH GAP. ALSO
INCREASED POPS FOR SHERIDAN WY EAST TOWARD BROADUS AND ALZADA.

TEMPERATURES BOTH DAYS WILL BE RUNNING ABOVE NORMAL THANKS TO THE
RIDGING ALOFT AND 700 MB TEMPERATURES RUNNING AROUND +5 TO +10 C.
OVERNIGHT LOWS BOTH DAYS WILL BE HELD UP BY LIGHT EASTERLY WINDS
AND ANY REMAINING MIDDLE AND HIGH CLOUD COVER FROM CONVECTION
EARLIER IN THE DAY/EVENING. CHURCH

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

EXTENDED PERIOD WILL BE IMPACTED BY AN UPPER LEVEL LOW OVER THE
PACIFIC NORTHWEST ON WEDNESDAY WHICH TRIES TO BEGIN MOVING BUT IS
OVER SOUTHERN SASKATCHEWAN BY SUNDAY. THIS SLOW MOVEMENT MEANS
THIS LOW WILL INFLUENCE THE WEATHER OVER MONTANA AND WYOMING BUT
ITS TRACK NORTH OF THE AREA MEANS ITS NOT STRONG FOR THE AREA
DYNAMICALLY BUT WILL GENERALLY KEEP CONVECTION IN THE FORECAST.

WEDNESDAY IS THE DAY FOR HIGHEST STRONG CONVECTION POTENTIAL AS AN
IMPULSE EJECTS AROUND THE LOW GIVING A NEGATIVE TILT TO THE FLOW
ALOFT. THE PATTERN ALSO ADVECTS IN SOME VERY WARM TEMPERATURES
ALOFT AND TRIES TO BRING A DRIER WESTERLY SURFACE FLOW FOR THE
WESTERN ZONES. CAPPING AND DOWNSLOPE COULD ERODE ANY CONVECTIVE
THREAT...BUT CONVECTIVE PARAMETERS ARE VERY HIGH WITH CAPES
PROGGED AROUND 2000-3000 J/KG AND DECENT LOW LEVEL SHEAR. BOTTOM
LINE...WEDNESDAY HAS SOLID UNCERTAINITY WITH IT AND COULD BE A
SIGNIFICANT SEVERE WEATHER DAY BUT AT THIS POINT IT IS EXPECTED
THAT GREATEST THREAT IS IN NORTHERN MONTANA.

WHAT HAS CHANGED IN THE MOST RECENT RUNS IS LOW DOES NOT EJECT AS
QUICKLY AS PREVIOUSLY INDICATED...WHICH GIVES A BETTER CHANCE FOR
THUNDER THURSDAY AND FRIDAY. TEMPERATURES WILL BE COOLER SO
THUNDER INTENSITY MAY NOT BE AS STRONG BUT UPPER LEVEL WINDS WILL
BE STRONGER SO SOME SHEAR IS AVAILABLE.

SATURDAY UPPER LOW AXIS CROSSES THE AREA AND THIS SHIFTS THE
MOISTURE NORTHEASTWARD AND IT DOES START LOOKING DRY SUNDAY INTO
MONDAY. TEMPERATURES WILL BE SEASONABLE AND AROUND 80 DEGREES.
BORSUM

&&

.AVIATION...

MOSTLY SUNNY CONDITIONS UNTIL AFTERNOON WITH MOUNTAIN CUMULUS
DEVELOPMENT. THUNDERSTORMS WILL DEVELOP DURING THE AFTERNOON AND
HAVE A BETTER CHANCE MOVING ONTO THE WESTERN AND CENTRAL PLAINS.
THUNDERSTORMS ARE POSSIBLE FOR KBIL...KLVM AND KSHR INTO THE
EVENING. CHAMBERS

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY TUE     WED     THU     FRI     SAT     SUN
-------------------------------------------------------
BIL 080 058/086 061/086 056/077 050/076 050/075 051/074
    1/B 22/T    24/T    42/T    33/T    22/T    22/T
LVM 081 047/085 053/083 049/072 040/073 042/074 047/076
    3/T 34/T    33/T    33/T    33/T    22/T    23/T
HDN 080 056/088 056/089 058/078 053/077 050/076 051/075
    1/B 12/T    23/T    33/T    33/T    22/T    22/T
MLS 079 057/087 061/088 062/081 055/077 055/077 055/077
    1/U 11/U    23/T    33/T    33/T    33/T    33/T
4BQ 079 055/087 058/090 059/081 055/078 052/077 052/077
    2/T 11/N    22/T    23/T    33/T    33/T    33/T
BHK 075 055/083 061/083 062/080 054/078 053/074 052/074
    1/U 11/N    22/T    32/T    44/T    43/T    33/T
SHR 079 053/085 055/086 055/078 050/076 048/075 047/074
    2/T 23/T    22/T    23/T    33/T    22/T    22/T

&&

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

&&

$$
WEATHER.GOV/BILLINGS