Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 091532
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
932 AM MDT WED APR 9 2014

.UPDATE...

NOT MUCH TO CHANGE THIS MORNING AS THE FORECAST LOOKS TO BE ON
TRACK. DID ADD A CHANCE OF THUNDERSTORMS TO THE SOUTHWEST
MOUNTAINS THIS AFTERNOON WITH STRONG DYNAMICS AND FRONTAL FORCING
SET TO IMPACT THAT REGION...ALONG WITH THE REST OF THE FORECAST
AREA. THE COLD FRONT CONTINUES TO PUSH SOUTHEAST THIS
MORNING...AND IS JUST NOW MOVING THROUGH GREAT FALLS...SO THERE
WILL STILL BE SEVERAL HOURS OF DAYTIME HEATING TO HELP DESTABILIZE
THE ATMOSPHERE ACROSS A GOOD PORTION OF OUR AREA BEFORE THE FRONT
BLASTS THROUGH WITH SCATTERED SHOWERS...A FEW THUNDERSTORMS...AND
VERY GUSTY NW WINDS. STILL LOOKS LIKE THE FRONT WILL CLEAR THE
AREA BY THIS EVENING...WITH SHOWERS LINGERING ACROSS THE SOUTHERN
HALF OF THE REGION. STC

&&

.SHORT TERM...VALID FOR TDY AND THU...

TODAY AND TONIGHT...A TRANSITION TO UNSETTLED WEATHER WILL BE
UNFOLDING TODAY AND FRIDAY AS THE UPPER LEVEL RIDGE OF HIGH
PRESSURE OVER THE AREA BREAKS DOWN. A STRONG UPPER LEVEL TROUGH
WILL MOVE ACROSS SOUTHERN CANADA TODAY AND WILL DRAG A STRONG COLD
FRONT THROUGH SOUTHERN MONTANA. THE FRONT WAS LOCATED OVER
EASTERN WASHINGTON STATE THIS MORNING AT 08Z AND CONVECTION WAS
ALREADY DEVELOPING AHEAD OF THE FRONT. THE FRONT IS EXPECTED TO
MOVE THROUGH BILLINGS BY 19Z AND MILES CITY AND BAKER BY 22Z.

STRONG CONVERGENCE AHEAD OF THE FRONT COMBINED WITH UPPER LEVEL
FORCING WITH THE WAVE...WILL BRING SHOWERS AND A FEW THUNDERSTORMS
TO THE AREA TODAY. BUFKIT SHOWING INVERTED V SOUNDINGS TODAY ALONG
WITH VERY STEEP LAPSE RATES. NAM INDICATING LI`S AROUND A -2C WITH
SURFACE BASED CAPES AROUND 400 J/KG THIS AFTERNOON. THESE FACTORS
COMBINED WILL ALLOW A FEW THUNDERSTORMS TO DEVELOP BY EARLY
AFTERNOON. 500 MB TEMPERATURES COOLING TO A -20C WITH THE UPPER
TROUGH MOVING THROUGH AND THIS WILL ALLOW A FEW STORMS TO MAYBE
PRODUCE SMALL HAIL ALONG WITH GUSTY WINDS. STRONG COLD AIR
ADVECTION BEHIND THE FRONT WILL ALLOW STRONG WINDS ALOFT TO MIX
DOWN TO THE SURFACE AND WIND SPEEDS OF 20 TO 30 MPH WITH GUSTS TO
45 MPH WILL BE POSSIBLE FOR SEVERAL HOURS OVER ENTIRE AREA.
TEMPERATURES WILL BE TRICKY TODAY BUT MOST LOCATIONS SHOULD SEE
LOW TO MID 60S WITH PRE-FRONTAL WARMING. POCKET OF WARM AIR STILL
OVER SOUTHEAST MONTANA FROM SHERIDAN...BROADUS TO EKALAKA AND
LOWER 70S ARE EXPECTED IN THESE AREAS AHEAD OF THE FRONT. GUSTY
WINDS WILL CONTINUE DURING THE EARLY EVENING HOURS BUT WILL
DECREASE AFTER SUNSET AS WINDS DECOUPLE FROM THE SURFACE WITH
NIGHTTIME INVERSION SETTING UP.

THURSDAY AND THURSDAY NIGHT...SHORTWAVE ENERGY IN NW FLOW ALOFT
WILL WORK WITH STEEP LAPSE RATES...DAYTIME HEATING...AND UPPER
LEVEL DIVERGENCE ASSOCIATED WITH ANOTHER STRONG JET MAX...TO
PRODUCE ISOLATED TO SCATTERED SHOWERS ACROSS THE AREA.
TEMPERATURES WILL CONTINUE TO RUN ABOVE NORMAL WITH HIGHS EXPECTED
IN THE UPPER 50S EAST TO THE LOWER 60S ELSEWHERE. RICHMOND

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

LEANED TOWARD THE ECMWF AGAIN FOR THIS FORECAST FOR THE SAT
THROUGH SUN SYSTEM AS THE NORMALIZED STANDARD DEVIATIONS FOR THE
ECMWF WERE SHOWING MORE CONFIDENCE IN IT/S FORECAST THAN THEY WERE
FOR THE GFS. THAT BEING SAID...THERE STILL WAS QUITE A BIT OF
UNCERTAINTY IN THE DETAILS OF THE PATTERN WITH EACH MODEL
MAINTAINING IT/S OWN SOLUTION FROM RUN TO RUN.

FRI WILL BE MAINLY DRY WITH HIGHS IN THE 60S UNDER A FLAT NW FLOW.
THE WEEKEND SYSTEM STARTS TO DIG INTO THE REGION FRI NIGHT AS A
SHORTWAVE DIGS INTO THE PACIFIC NW. THE WAVE WILL PUSH A COLD
FRONT S INTO THE AREA WITH AN INCREASING CHANCE FOR SHOWERS
THROUGH THE NIGHT. THE SHORTWAVE WILL CONTINUE TO DIG SE ON SAT
AND MOISTURE WILL OVERSPREAD THE SW THIRD OF THE AREA. THE ECMWF
WAS MORE AGGRESSIVE WITH THE MOISTURE AND CORRESPONDING QPF THAN
THE GFS. SPLIT SAT POPS INTO 6 HOUR PERIODS TO REFLECT INCREASING
CHANCES FOR PRECIPITATION THROUGH THE DAY AND CONTINUED THE HIGH
POPS OVER THE CENTRAL AND W. 850 MB TEMPERATURES WERE FORECAST TO
BE NEAR OR ABOVE ZERO DEGREES C BY DAY/S END ON BOTH MODELS SO
KEPT THE LOWER ELEVATIONS AS ALL RAIN FOR NOW.

850 MB TEMPERATURES WILL FALL BELOW ZERO DEGREES C ON SAT NIGHT
HOWEVER...WHICH WILL CHANGE THE PRECIPITATION TO ALL SNOW. THE
BEST CHANCES FOR SEVERAL INCHES OF ACCUMULATION WILL BE OVER N AND
NE UPSLOPE AREAS AND OVER THE MOUNTAINS. CONTINUED THE HIGH POPS
OVER WESTERN AND S CENTRAL AREAS PER THE ECMWF. POPS WILL DECREASE
OVER THE AREA ON SUN AS THE MAIN WAVE CONTINUES TO PUSH S. A
RAIN/SNOW MIX WILL RETURN TO THE AREA AS 850 MB TEMPERATURES START
TO CLIMB ABOVE ZERO. HOWEVER...THE ECMWF REMAINED COLDER THAN THE
GFS SO TEMPERATURES AND PRECIPITATION TYPE WERE A BIT UNCERTAIN.
IF THE ECMWF SOLUTION PANS OUT...A HALF INCH TO AN INCH OF LIQUID
PRECIPITATION WILL BE POSSIBLE OVER PARTS OF THE AREA WHICH COULD
CAUSE RISES ON THE RIVERS. WILL NEED TO KEEP A CLOSE EYE ON THIS
SYSTEM AS IT GETS CLOSER IN TIME.

MODELS SOLUTIONS DIVERGE EVEN MORE AFTER SUN...AS THE ECMWF
MAINTAINS A NW FLOW OVER THE AREA AND THE GFS HAS A PROGRESSIVE
WESTERLY FLOW. MON DID LOOK DRY AND WARMER...BUT WITH NO
AGREEMENT FOR TUE AND WED...WENT WITH CLIMATOLOGICAL POPS AND
CONSALL TEMPERATURES. ARTHUR

&&

.AVIATION...

LOW-LEVEL WIND SHEAR AT KMLS EARLY THIS MORNING WILL END WITH
MIXING OF WEST WINDS BY 16-18Z. AN APPROACHING COLD FRONT WILL
BRING SCATTERED SHOWERS AND A FEW THUNDERSTORMS BY THIS AFTERNOON.
STORMS WILL HAVE THE CAPABILITY TO PRODUCE SMALL HAIL AND WIND
GUSTS OVER 40 KTS...AND LOCAL MVFR CONDITIONS. MOUNTAINS WILL
BECOME OBSCURED AT TIMES AS WELL. FRONTAL NW WINDS WILL BE GUSTY
EVEN WITHOUT THE SHOWER ACTIVITY...WITH WIDESPREAD 25-35 KT GUSTS
AT ALL TAF SITES. SHOWERS AND WINDS WILL DECREASE THIS EVENING AND
VFR WILL PREVAIL THRU THE NIGHT. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY THU     FRI     SAT     SUN     MON     TUE
-------------------------------------------------------
BIL 066 036/062 038/068 041/049 029/044 030/058 037/055
    6/T 22/W    10/B    36/R    63/O    11/U    12/W
LVM 064 032/060 035/065 036/049 026/047 029/057 034/054
    6/T 22/W    10/N    36/O    63/O    11/U    13/W
HDN 068 033/064 034/069 040/050 029/045 027/059 032/056
    6/T 52/W    10/B    36/R    63/O    11/U    12/W
MLS 068 034/062 035/067 040/050 027/043 026/056 032/055
    6/T 12/W    10/B    24/R    31/U    11/U    12/W
4BQ 071 034/063 034/069 041/052 027/044 026/056 030/055
    6/T 62/W    10/B    34/R    52/O    11/U    12/W
BHK 069 032/058 032/066 037/049 025/040 023/051 027/052
    6/T 12/W    10/B    23/R    31/B    11/U    12/W
SHR 070 034/061 033/068 037/050 027/042 025/055 032/054
    6/T 62/W    10/U    25/R    76/O    21/U    12/W

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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