Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 032140
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
340 PM MDT MON AUG 3 2015

.SHORT TERM...VALID FOR TUE AND WED...

MODELS ARE IN FAIRLY GOOD AGREEMENT IN BRINGING UNSETTLED WEATHER
TO OUR FORECAST AREA THE NEXT COUPLE OF DAYS. SATELLITE IS
CURRENTLY SHOWING AN UPPER LOW ALMOST STATIONARY OVER NORTHEAST
UTAH INTO SOUTHWEST WYOMING. THIS LOW AND ITS ASSOCIATED ENERGY
AND MONSOONAL MOISTURE WILL SLOWLY SHIFT NORTHEAST TONIGHT THROUGH
THE DAY TUESDAY. AREAS OF VORTICITY WILL MOVE INTO OUR WESTERN
AREAS BY MID MORNING TO LATE MORNING TUESDAY RESULTING IN SHOWERS
AND THUNDERSTORMS DEVELOPING ACROSS OUR WEST DURING THE MORNING
AND APPROACHING THE BILLINGS AREA BY LATE MORNING OR EARLY
AFTERNOON BEFORE SHIFTING INTO OUR EASTERN AREAS BY MID AFTERNOON
THROUGH THE EVENING HOURS.

PLENTY MID AND LOW LEVEL MOISTURE WILL BE IN PLACE AS SOUNDINGS
SHOW DEEP MOISTURE THROUGH 700MB. A LOW LEVEL SURFACE FLOW FROM
THE EAST/SOUTHEAST WILL ALSO DRAW IN HIGHER DEWPOINTS FROM THE
CENTRAL PLAINS. WE ARE ACTUALLY DEALING WITH AUGUST MONSOONAL
MOISTURE BUT ALSO A PATTERN SIMILAR TO JUNE GIVEN THE ADVECTION OF
HIGHER DEWPOINTS FROM THE PLAINS. HOWEVER...THE UPPER FLOW AND
STEERING WINDS WILL BE LIGHT SO THE THUNDERSTORMS ARE EXPECTED TO
BE SLOW-MOVERS. MODELS PLACE COPIOUS AMOUNTS OF QPF ACROSS OUR
CENTRAL AND ESPECIALLY OUR EASTERN AREAS FOR TOMORROW. IN
ADDITION...PRECIPITAL WATERS WILL BE AROUND 1.50". AS A RESULT OF
THE ABOVE...AND GIVEN SOME RECENT NEW BURN SCARS...WE HAVE ISSUED
A FLASH FLOOD WATCH WITH THIS FORECAST FROM ROSEBUD COUNTY
EASTWARD FOR TUESDAY AFTERNOON AND EVENING. THE STORM PREDICTION
CENTER PLACED THIS AREA IN A MARGINAL RISK FOR A SEVERE
THUNDERSTORM SO THIS CAN`T BE RULED OUT OF THE PICTURE. GIVEN THE
LACK OF ORGANIZED SHEAR WE OPTED NOT TO MENTION SEVERE IN THE
GRIDS BUT I DID ADD HEAVY RAINFALL WORDING IN THE FORECAST. GIVEN
EXTENSIVE CLOUD COVER EXPECTED ALONG WITH NUMEROUS
SHOWERS/THUNDERSTORMS...WE LOWERED HIGH TEMPERATURES A FEW
DEGREES INTO THE UPPER 70S TO MIDDLE 80S.

FOR WEDNESDAY...ANOTHER LOW AND TROUGH APPROACH THE PACIFIC
NORTHWEST COAST ALLOWING THE FLOW ALOFT TO BECOME SOUTHWEST. A FEW
DISTURBANCES WITHIN THE FLOW WILL MOVE ACROSS THE FORECAST AREA
BRINGING CONTINUED CHANCES FOR SHOWERS AND THUNDERSTORMS. SHEAR
WILL BE A BIT BETTER SO A STRONG THUNDERSTORM IS NOT OUT OF THE
QUESTION. TEMPERATURES WILL STILL BE AT OR SLIGHTLY BELOW NORMAL
WITH READINGS IN THE LOWER TO MIDDLE 80S. HOOLEY

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

TWO PERIODS OF ACTIVE WEATHER ARE EXPECTED IN THE EXTENDED WITH
THE GLOBAL GUIDANCE IN VERY GOOD AGREEMENT FOR MOST OF THE
PERIOD. THURSDAY WILL BEGIN WITH A SHORTWAVE PROGRESSING THROUGH
THE FORECAST AREA EARLY IN THE MORNING. THIS SHOULD BE ABLE TO
GENERATE SHOWERS AND AN ISOLATED THUNDERSTORM ALONG AND WEST OF A
LINE THROUGH BILLINGS EARLY IN THE MORNING/EARLY-AFTERNOON. LATER
IN THE DAY THE FRONT ASSOCIATED WITH THE UPPER LOW TO THE NORTH
PUSHES THESE SHOWERS AND THUNDERSTORMS EAST AND NORTHEAST IN THE
AFTERNOON HOURS.

AFTER THE FRONT...CONDITIONS WILL BE FAIRLY TRANQUIL ON FRIDAY
AND EARLY SATURDAY AS LARGE SCALE SUBSIDENCE TAKES OVER BEHIND
THE UPPER LEVEL LOW. WHILE WE ARE NOT EXPECTING MUCH OF A COOL-
DOWN BEHIND THIS FRONT...LOWER HEIGHTS ALOFT SHOULD KEEP
TEMPERATURES NEAR AVERAGE WITH LITTLE TO NO CHANCES FOR RAIN. IF
WE GET ANY RAIN IN THIS PERIOD EXPECT IT TO BE LATER SATURDAY AS
MID-LEVEL MOISTURE AND SOME DIFFLUENCE ALOFT MOVE IN FROM THE
WEST AHEAD OF THE NEXT RAINMAKER.

THE LAST TWO DAYS OF THE PERIOD LOOK TO BRING SOME WARMER
TEMPERATURES AND THE RETURN OF SOME RAIN CHANCES. A DECAYING
SHORTWAVE...CURRENTLY MEANDERING IN THE NORTHEASTERN
PACIFIC...COULD BRING SOME RAIN EARLY SUNDAY AS ITS ADVECTED
NORTHEAST. ITS EARLY MORNING/AFTERNOON TIMING COULD KEEP
TEMPERATURES DOWN ON SUNDAY. MONDAY LOOKS TO BE A WARMER DAY AS
SHORTWAVE RIDGING BUILDS IN AHEAD OF THE NEXT UPPER LEVEL LOW
APPROACHING FROM THE NORTHWEST. EXPECT ISOLATED SHOWER AND
THUNDERSTORM DEVELOPMENT MONDAY AFTERNOON.

DOBBS


&&

.AVIATION...

VFR CONDITIONS SHOULD PREVAIL FOR THE PERIOD OUTSIDE ANY ISOLATED
THUNDERSTORM DEVELOPMENT. KSHR COULD SEE SOME VCTS AROUND 22-01Z
WITH TSTORM DEVELOPMENT NEAR/AROUND THE BIG HORNS. THESE ISOLATED
STORMS COULD PRODUCE LOCAL MVFR/IFR CONDITIONS. LATER THIS
EVENING...MOSTLY AFTER 06Z...ISOLATED SHOWER DEVELOPMENT IS
EXPECTED AT ALL TERMINALS EXCEPT FOR KMLS THROUGH THE REMAINDER OF
THE TAF PERIOD. DOBBS

&&

.PRELIMINARY POINT TEMP/POPS...

    TUE     WED     THU     FRI     SAT     SUN     MON
-----------------------------------------------------------
BIL 064/079 058/083 058/086 057/085 058/086 059/084 058/089
    26/T    33/T    32/T    21/B    13/T    32/T    21/B
LVM 060/081 053/080 050/082 049/084 052/081 052/080 052/085
    36/T    34/T    42/T    21/B    13/T    33/T    32/T
HDN 062/084 057/085 057/087 055/086 056/090 058/086 057/090
    27/T    43/T    32/T    21/B    12/T    22/T    21/B
MLS 064/086 059/086 060/086 058/085 058/087 060/084 059/089
    27/T    72/T    44/T    21/B    13/T    33/T    31/B
4BQ 062/085 058/085 059/084 058/085 058/087 059/084 058/088
    27/T    62/T    44/T    21/B    13/T    33/T    31/B
BHK 058/086 058/083 059/081 056/083 054/084 058/080 056/085
    14/T    72/T    44/T    32/T    12/T    33/T    31/B
SHR 060/077 051/085 054/083 053/085 054/086 055/084 054/087
    36/T    43/T    32/T    21/U    13/T    32/T    21/B

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...FLASH FLOOD WATCH IN EFFECT FROM TUESDAY AFTERNOON THROUGH
      TUESDAY EVENING FOR ZONES 31>33-36-37-58.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS



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