Area Forecast Discussion
Issued by NWS Billings, MT

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000
FXUS65 KBYZ 220932
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
332 AM MDT MON SEP 22 2014

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

A WEAK BUT ADEQUATELY MOIST UPPER LOW WAS CURRENTLY SPINNING OVER
NORTHERN UTAH AND SOUTHERN IDAHO. THIS SYSTEM PRODUCED QUITE A BIT
OF LIGHTNING OVER NEVADA AND UTAH YESTERDAY AS IT PROGRESSED
SLOWLY NORTHEAST. AN AMPLIFIED RIDGE SITTING OVER EASTERN MONTANA
WAS CAUSING THE DEEPER MOISTURE WITH THIS SYSTEM TO DRY OUT SOME.
THAT BEING SAID...OVER AN INCH OF PRECIPITABLE WATER WAS RECORDED
AT BOISE SUNDAY EVENING. PRECIPITABLE WATER ANOMALIES WERE 4
STANDARD DEVIATIONS ABOVE NORMAL FOR THIS TIME OF YEAR...SO
DESPITE A LITTLE DRYING...THERE WILL BE PLENTY OF MOISTURE AROUND
FOR SHOWERS. JET DYNAMICS WERE VERY WEAK WITH THE LOW...SO RELYING
ON INSTABILITY...CYCLONIC FLOW AND OROGRAPHICS TO PRODUCE THE
SHOWERS TODAY. COULD BE LOCALLY HEAVY RAIN IN ANYTHING THAT FORMS
TODAY. HIGH RESOLUTION SHORT RANGE MODELS KEEP MOST OF THE
ACTIVITY OVER SOUTHERN LOCATIONS. WILL KEEP POPS HIGHEST SOUTH OF
BILLINGS AND ESPECIALLY OVER THE MOUNTAINS AND ALONG THE
FOOTHILLS. THE BEST CHANCE OF SHOWERS FOR BILLINGS WILL BE LATE
MORNING AND THROUGH THE AFTERNOON WITH BEST INSTABILITY.

THE SYSTEM KICKS INTO THE DAKOTAS TUESDAY AND POPS WILL TRIM BACK
TONIGHT AND TUESDAY FROM WEST TO EAST BECAUSE OF SUCH. WEAK ENERGY
STREAMS ACROSS A DEVELOPING RIDGE TUESDAY AFTERNOON AND COMBINES
WITH SOME WEAK INSTABILITY TO GENERATE AT LEAST A SLIGHT CHANCE OF
SHOWERS OR THUNDERSTORMS FOR THE MOUNTAINS AND FOOTHILLS. 700MB
TEMPERATURES INCREASE TO AROUND 10C AND THIS SHOULD ALLOW HIGHS TO
REACH THE LOWER 80S. THE RIDGE STARTS TO AMPLIFY TUESDAY NIGHT FOR
A DRY NIGHT AND FOR EVEN WARMER TEMPERATURES ON WEDNESDAY. TWH

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

MINIMAL CHANGES TO THE EXTENDED FORECAST THIS MORNING...WITH ONLY
A FEW MINOR TWEAKS TO CLEAN UP BORDERS.

MODELS REMAIN IN GOOD AGREEMENT WEDNESDAY THROUGH FRIDAY...WITH
UNSEASONABLY WARM AND DRY CONDITIONS ACROSS THE REGION UNDER AND
UPPER LEVEL RIDGING. 850MB TEMPS OF 26 TO 28C AND 700MB TEMPS OF
13 TO 15C POINT TO SURFACE TEMPS AROUND 90 DEGREES ACROSS MUCH OF
THE REGION FOR THURSDAY .

MODEL AGREEMENT APPEARS TO BE IMPROVING SOME FOR THE WEEKEND AND
EARLY NEXT WEEK...WITH TIMING TRENDING MORE TOWARD THE SLOWER TACK
OF THE ECMWF. HOWEVER THERE CONTINUE TO BE ISSUES WITH SPECIFICS
OF TRACK AND FORM OF OPEN TROF / UPPER LEVEL LOW ACROSS THE REGION
FOR THE WEEKEND...SO UNCERTAINTY REMAINS RELATIVELY HIGH.
INDICATIONS ARE STILL FOR A PERIOD OF WET AND COOLER WEATHER
BEGINNING AS EARLY AS SATURDAY MORNING IN THE WEST...BUT POSSIBLY
HOLDING OFF UNTIL SATURDAY NIGHT. THE SPECIFICS OF HOW THE LOW
PRESSURE SYSTEM MOVES ACROSS THE REGION WILL MAKE ALL THE
DIFFERENCE IN WHERE PRECIP FALLS AND WHERE GREATEST AMOUNTS WILL
BE. HAVE MAINLY BROADBRUSHED SLIGHT POPS ACROSS THE PLAINS AT THIS
TIME...WITH BETTER POTENTIAL IN THE HIGH TERRAIN. TEMPS ARE
EXPECTED TO RETURN TO AROUND NORMAL...OR SLIGHTLY BELOW...WITH
HIGHS IN THE UPPER 60S AND 70S FOR THE WEEKEND AND EARLY NEXT
WEEK. AAG

&&

.AVIATION...

SCATTERED SHOWERS ARE MOVING INTO SOUTH CENTRAL MONTANA THIS
MORNING...AS A WEAK SYSTEM LIFTS OUT OF THE GREAT BASIN. SHOWERS
AND THUNDERSTORMS WILL CONTINUE TO SPREAD ACROSS MUCH OF THE
REGION TODAY...WITH GREATEST COVERAGE IN OUR SOUTH ALONG THE MT/WY
BORDER. EXPECT LOCAL MVFR CONDITIONS AND OCCASIONAL MOUNTAIN
OBSCURATIONS THROUGH THE DAY. OTHERWISE...VFR CONDITIONS SHOULD
PREVAIL ELSEWHERE. AAG

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY TUE     WED     THU     FRI     SAT     SUN
-------------------------------------------------------
BIL 079 055/083 056/086 057/090 057/084 052/069 046/067
    3/T 21/B    10/U    00/U    01/U    23/T    33/T
LVM 077 049/082 048/085 049/087 049/081 045/066 040/064
    4/T 21/B    10/U    00/U    12/T    33/T    43/T
HDN 079 052/084 051/088 056/090 056/086 050/072 045/070
    3/T 21/B    10/U    00/U    01/U    22/T    32/T
MLS 083 054/085 055/089 058/091 058/087 053/073 049/071
    1/U 21/B    10/U    00/U    01/U    12/T    32/T
4BQ 082 054/083 052/088 057/091 057/087 055/073 050/071
    2/T 31/B    10/U    00/U    01/U    12/T    22/T
BHK 079 050/081 050/085 054/087 054/086 055/073 049/070
    1/U 21/B    10/U    00/U    01/U    11/B    22/T
SHR 076 050/081 049/085 052/088 052/085 050/070 045/068
    3/T 41/B    10/U    00/U    01/U    22/T    33/T

&&

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

&&

$$
WEATHER.GOV/BILLINGS


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