Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 150917
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
317 AM MDT TUE APR 15 2014

.SHORT TERM...VALID FOR TDY AND WED...

SOMEWHAT ACTIVE WEATHER PATTERN WILL RETURN BY THIS EVENING AND
CONTINUING THROUGH THE DAY WEDNESDAY. MODELS ARE NOT IN THE BEST
AGREEMENT NOR CONSISTENT THIS MORNING WITH THE NEXT STORM SYSTEM
ESPECIALLY IN REGARDS TO QPF.

HIGH PRESSURE RIDGE THAT WAS BRIEFLY OVER THE FORECAST AREA
MONDAY WILL BEGIN TO BREAK DOWN TODAY AS ANOTHER DISTURBANCE
WITHIN THE NORTHWEST FLOW ALOFT MOVES SOUTHEAST OUT OF CANADA AND
ACROSS SOUTHERN MONTANA AND NORTHERN WYOMING. A SURFACE LOW OVER
SOUTHERN CANADA WILL MOVE SOUTHEAST INTO EASTERN MONTANA AND THE
WESTERN DAKOTAS BY LATE THIS AFTERNOON SWEEPING A COLD FRONT
ACROSS OUR AREA. THIS SURFACE LOW IS ALLOWING FOR PRESSURE FALLS
ALONG THE EAST SLOPES OF THE ROCKIES AND TIGHT PRESSURE GRADIENTS
ACROSS THE UPPER YELLOWSTONE AND STILLWATER VALLEYS. WINDS AT
LIVINGSTON BRIEFLY HIT A SUSTAINED 41 MPH LATE LAST EVENING BUT
HAVE SINCE STAYED BELOW ADVISORY CRITERIA. PRESSURE GRADIENTS WILL
STAY JUST WEAK ENOUGH TO LIMIT AN EXTENDED PERIOD OF STRONG WINDS
SO WILL NOT ISSUE ANY WIND ADVISORY AT THIS TIME. PRESSURE
GRADIENTS WILL SLACKEN AND THE WINDS WILL DECREASE SOMEWHAT AS THE
FRONT MOVES THROUGH LATER THIS MORNING.

UPPER LEVEL DISTURBANCE OVER BRITISH COLUMBIA WILL MOVE ACROSS
OUR AREA TODAY BRINGING INCREASING SHOWER CHANCES. MODELS HAVE
SLOWED THE ARRIVAL OF THE SHOWERS SO BEST CHANCES LOOK TO BE LATER
THIS AFTERNOON INTO THIS EVENING. 850MB TEMPERATURES LOOK TO STAY
ABOVE FREEZING THROUGH MOST OF THE NIGHT SO PRECIP SHOULD BE IN
THE FORM OF RAIN TODAY AND A RAIN/SNOW MIX THIS EVENING WITH
SHOWERS BECOMING ALL SNOW LATE TONIGHT INTO WEDNESDAY MORNING.
WINDS WILL BECOME NORTHWEST THIS AFTERNOON THEN NORTHERLY TONIGHT
BEFORE SWITCHING TO THE NORTHEAST ON WEDNESDAY. UPSLOPE FLOW IS
NOT NEARLY AS STRONG NOR DEEP AS THE LAST SYSTEM THIS PAST WEEKEND
SO SIGNIFICANT SNOW ACCUMULATIONS ALONG THE FOOTHILLS ARE NOT
EXPECTED AT THIS TIME. HOWEVER...MODELS HAVE BEEN WAVERING ON
AMOUNT AND PLACEMENT OF QPF AND GIVEN SOMEWHAT UNSTABLE NORTHWEST
FLOW ALOFT WILL NEED TO MONITOR THIS SYSTEM CLOSELY FOR LATE
TONIGHT INTO WEDNESDAY. FOR NOW...KEPT ANY ACCUMULATIONS MINOR.
TEMPERATURES WILL WARM CLOSE TO NORMAL TODAY BEFORE DROPPING WELL
BELOW NORMAL ON WEDNESDAY. HOOLEY

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

THE EXTENDED PERIOD BEGINS WITH THE EXIT OF A SHORT WAVE TROUGH
TO THE EAST ON THURSDAY. UNSTABLE NORTHWEST FLOW BEHIND THE TROUGH
WILL LEAD TO SOME LINGERING SCATTERED RAIN AND SNOW SHOWERS.
DOWNSLOPE WIND WILL GIVE THE MERCURY A NUDGE...BUT WE WILL STILL
BE BELOW SEASONAL NORMALS FOR THURSDAY. HOWEVER...THE LATTER PART
OF THE WEEK INTO EARLY NEXT WEEK LOOKS RATHER MILD. FRIDAY WILL
INITIALLY SEE A SHORT WAVE RIDGE BREAK DOWN AS A FAST MOVING
TROUGH SLIDES THROUGH THE REGION. THIS WILL LIKELY PRODUCE A LINE
OF SHOWERS THAT RACES ACROSS OUR FORECAST AREA THROUGH FRIDAY
NIGHT. SATURDAY AND SUNDAY LOOK DRY AND MILD WITH RIDGING/ZONAL
FLOW DEPICTED BY PROGGS. HOWEVER...THERE IS QUITE A BIT OF SPREAD
YET BETWEEN THE GFS AND ECMWF FOR THE EARLY PART OF NEXT WEEK AS
RIDGING AND TROUGHING LOOK OUT OF SYNC...AND THE GFS IS HINTING AT
A LARGE CLOSED UPPER LOW FORMING NEXT WEEK TO OUR SOUTH...WHILE
THE ECMWF TRACKS THIS UPPER LOW MUCH FURTHER NORTH. SO NOT MUCH
CONFIDENCE IN HOW THIS WILL PLAY OUT...BUT WE SHOULD STAY MILD
INTO AT LEAST MONDAY AND PROBABLY TUESDAY. BT
&&

.AVIATION...

VFR CONDITIONS ARE EXPECTED AT OUR TAF SITES THROUGH TODAY. LOOK
FOR SW WINDS GUSTING TO NEAR 50 MPH TO CONTINUE AT KLVM THROUGH
AT LEAST 21Z BEFORE DIMINISHING SOMEWHAT. SCATTERED AND POSSIBLY
BANDED AREAS OF SHOWERS WILL DEVELOP ACROSS THE REGION THIS
AFTERNOON AND INTO THE EVENING WITH MOUNTAIN OBSCURATIONS
POSSIBLE. BT
&&

.PRELIMINARY POINT TEMP/POPS...

    TDY WED     THU     FRI     SAT     SUN     MON
-------------------------------------------------------
BIL 057 033/042 028/050 033/063 038/063 038/070 042/069
    3/W 66/W    32/W    22/W    30/B    00/U    00/U
LVM 054 030/040 026/050 031/058 034/060 035/066 040/066
    6/W 67/W    32/W    13/W    20/U    00/U    01/B
HDN 060 033/041 025/052 032/066 036/064 037/072 039/070
    2/W 66/W    32/W    21/B    30/B    00/U    00/U
MLS 061 032/040 026/049 029/062 034/061 037/070 039/068
    2/W 64/W    33/W    21/B    30/B    00/U    00/U
4BQ 060 033/041 024/050 029/064 034/062 036/070 038/069
    1/N 66/W    22/W    21/B    30/B    00/U    00/U
BHK 057 029/037 025/042 025/056 031/056 033/069 037/066
    1/B 44/W    23/W    21/B    30/B    00/U    00/U
SHR 058 033/041 027/050 028/064 033/061 035/069 038/068
    2/W 76/W    31/B    11/B    20/U    00/U    00/U

&&

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

&&

$$
WEATHER.GOV/BILLINGS



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