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448
FXUS65 KBYZ 240937
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
337 AM MDT THU APR 24 2014

.SHORT TERM...VALID FOR TDY AND FRI...

A DIRTY RIDGE BUILDS OVER THE AREA TODAY FOR SLIGHTLY WARMER
TEMPERATURES. HOWEVER PACIFIC MOISTURE AND ENERGY SLIDING UNDER
THE RIDGE WILL BRING SNOW SHOWERS TO THE MOUNTAINS AND ISOLATED TO
SCATTERED SHOWERS TO THE LOWER ELEVATIONS TODAY. DOWNSLOPE WIND
GRADIENT WILL KEEP MUCH OF THE PRECIPITATION FROM REACHING THE
GROUND BUT COULD SEE A SHOWER WET THE GROUND HERE AND THERE.
BREEZY CONDITIONS WILL DEVELOP TODAY BUT WIND SPEEDS WILL BE
SIGNIFICANTLY LESS THAN YESTERDAY. TEMPERATURES TONIGHT WILL BE IN
THE 30S TO LOWER 40S WITH WITH A GOOD DEAL OF CLOUD COVER OVER THE
REGION. ANOTHER WEAK DISTURBANCE CROSSES THE AREA TONIGHT KEEPING
LOW PRECIPITATION CHANCES IN THE FORECAST.

FOR FRIDAY...TROF ALONG THE PACIFIC COAST RAPIDLY AMPLIFIES AS
STRONG ENERGY DIVES OUT OF THE GULF OF ALASKA INTO THE CALIFORNIA
COAST. THIS QUICKLY BACKS THE FLOW ALOFT TO THE SOUTHWEST AND THEN
SOUTH BY FRIDAY EVENING...WITH DIFFLUENCE INCREASING ACROSS THE
AREA THROUGH THE DAY. SEVERAL PIECES OF ENERGY AND A COPIOUS
PACIFIC MOISTURE FETCH OVER RIDE THE AREA DURING THE AFTERNOON AND
EVENING HOURS. AT THE SURFACE THE INCREASINGLY DIFFLUENT SOUTHERLY
FLOW INDUCES SURFACE CYCLOGENESIS TO THE WEST OF THE AREA WHICH
PULLS THE LOW LEVEL WINDS AROUND TO THE EAST DURING THE DAY. THIS
COMBINATION OF MOISTURE ADVECTION...UPPER LEVEL LIFT...MID LEVEL
ENERGY AND UPSLOPE WINDS IS FAVORABLE FOR PRECIPITATION FRIDAY AND
FRIDAY NIGHT. EXPECT PRECIPITATION TO DEVELOP OVER SOUTHWESTERN
MOUNTAINS FRIDAY MORNING AND EXPAND NORTHEASTWARD THROUGH THE
EVENING HOURS. A DRY SLOT WILL BEGIN WORKING INTO THE AREA LATE
EVENING FROM THE SOUTH SO TRENDED POPS DOWN OVERNIGHT INTO
SATURDAY MORNING. FOR AREAS WEST OF ROSEBUD COUNTY THIS LOOKS LIKE
AN OPPORTUNITY TO PICK UP MAYBE A QUARTER OF AN INCH OF RAIN IN
THE LOWER ELEVATIONS AND 3 TO 6 INCHES OF SNOW FOR MOUNTAIN
LOCATIONS ABOVE 7500 FEET. CHAMBERS

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

DEVELOPING TROF ALONG THE PAC COAST WILL PUSH INTO THE
INTERMOUNTAIN WEST OVER THE NEXT COUPLE DAYS...THEN INTENSIFY IN
THE HIGH PLAINS THIS WEEKEND INTO EARLY NEXT WEEK...RESULTING IN A
POTENTIALLY SIGNIFICANT AND LONG DURATION PCPN EVENT ESPECIALLY
FOR OUR EASTERN PARTS. MODELS ARE ACTUALLY IN DECENT AGREEMENT IN
SHOWING A MID LEVEL LOW CLOSING OFF IN EASTERN CO BY 12Z SUN...
THEN LIFTING TO NE/SD BY 12Z MON. IMPRESSIVE MAGNITUDES OF
ASCENT/MOISTURE TRANSPORT WILL EXIST AHEAD OF THIS LOW...WITH PCPN
BECOMING FOCUSED IN OUR EAST ALONG A LOW TO MID LEVEL CONVERGENT
ZONE. THERE ARE A FEW FACTORS THAT CERTAINLY GIVE CREDENCE TO A
SLOWER EVOLVING AND MORE NORTHWESTWARD TRACKING LOW. THESE
INCLUDE A STRONG BLOCKING RIDGE TO OUR NORTH...A NWLY JET WITH
ADDITIONAL SHORTWAVE ENERGY FROM THE PAC NW TO CENTRAL
ROCKIES...AND AN ANOMALOUS SW-MOVING LOW WHICH WILL CROSS THE
GREAT LAKES AND PHASE WITH THE PLAINS LOW TOWARD THE MIDDLE OF
NEXT WEEK. SO WITH CONFIDENCE HAVE RAISED POPS ACROSS OUR EAST
SUN-TUE. UNCERTAINTY EXISTS REGARDING SFC TEMPS AND POTENTIAL
SNOWFALL. 00Z GFS REMAINS THE COLDEST OF ALL MODELS SHOWING 850MB
TEMPS TO -2C SUN NITE AND COLDER MON NITE. OTHER MODELS SHOW
VALUES CLOSER TO 0C. SO SOME WET SNOWFALL IS A POSSIBILITY
ESPECIALLY FOR THE CENTRAL/EASTERN RIDGES AND THE BIG HORN
MTNS...WHICH WILL BE FAVORED ONCE NW FLOW DEEPENS ON SUNDAY. EVEN
W/OUT THE SNOW THE PERIOD OF COLD AND WET WEATHER WILL BE
HAZARDOUS TO YOUNG LIVESTOCK.

BACKING UP TO SATURDAY...THE INITIAL STAGE OF THIS EVENT...UNSTABLE
AND INCREASINGLY DIFFLUENT SOUTH FLOW ALOFT WILL RESULT IN
PLENTY OF SHOWERS AND SOME THUNDERSTORM ACTIVITY SAT INTO SAT
NITE. THIS INCLUDES BILLINGS. SHEAR PROFILES ACTUALLY FAVOR SOME
STRONGER STORMS IN OUR SE NEAR INVERTED SFC TROF.

A PERIOD OF BELOW NORMAL TEMPS CAN BE EXPECTED FROM SUNDAY PERHAPS
ALL THE WAY TO WEDNESDAY AS WE REMAIN UNDER THE INFLUENCE OF
STRONG CYCLONIC FLOW ALOFT...DEEP EAST WINDS AND AN EVENTUAL
CANADIAN SFC HIGH. HAVE DROPPED EXPECTED HIGH TEMPS THRU EACH OF
THESE DAYS...BUT LEFT ALONE OR RAISED LOW TEMPS A BIT GIVEN PCPN
AND CLOUD COVER ANTICIPATED THRU THE PERIOD.

SHOULD SEE DRYING AND MODERATING TEMPS BY WEDNESDAY OR THURSDAY
OF NEXT WEEK AS THE LOW FINALLY DEPARTS.

JKL
&&

.AVIATION...

VFR CONDITIONS WILL PREVAIL TODAY WITH SCATTERED TO BROKEN MID
AND HIGH CLOUD. PACIFIC DISTURBANCE WILL ALLOW FOR ISOLATED TO
SCATTERED SHOWERS ALONG AND WEST OF A KBIL-KSHR LINE THIS
AFTERNOON AND EVENING...AND A FEW MTN OBSCURATIONS ARE EXPECTED.
WESTERLY WINDS WILL GUST TO 25-35 KTS...ESPECIALLY NEAR THE
FOOTHILLS. JKL
&&

.PRELIMINARY POINT TEMP/POPS...

    TDY FRI     SAT     SUN     MON     TUE     WED
-------------------------------------------------------
BIL 061 040/061 041/058 040/050 035/053 036/051 038/059
    2/W 15/W    56/T    87/W    33/W    33/W    21/B
LVM 054 036/054 036/054 038/056 034/055 034/058 035/059
    3/W 36/W    68/T    85/W    32/W    23/W    11/B
HDN 062 036/064 039/064 037/049 033/052 032/051 032/059
    2/W 25/W    54/T    78/W    54/W    33/W    21/B
MLS 061 039/065 044/065 040/045 033/048 032/047 033/055
    0/N 22/W    53/T    78/W    86/W    43/W    21/B
4BQ 061 037/065 042/070 040/047 033/047 032/046 032/054
    0/B 23/W    43/T    78/W    86/W    53/W    21/B
BHK 058 037/063 041/063 038/045 033/045 030/044 030/052
    0/N 22/W    43/T    78/W    86/W    53/W    21/B
SHR 059 035/062 038/067 038/048 034/049 033/050 032/056
    1/B 24/W    53/T    68/W    64/W    33/W    22/W

&&

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

&&

$$
WEATHER.GOV/BILLINGS




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