601 
FXUS65 KBYZ 190925
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT 
325 AM MDT MON MAY 19 2014

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

AS A RESULT OF THE RAIN THAT FELL ACROSS MUCH OF THE REGION
SUNDAY AFTERNOON/EVENING AND SOME LIGHT WINDS THIS MORNING...WE
WILL SEE PATCHY FOG ACROSS THE AREA. LOOK FOR FOG TO BURN OFF BY
MID MORNING. ATTENTION THEN SHIFTS TO THE POTENTIAL FOR MORE
SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND
EVENING...PARTICULARLY ACROSS THE WESTERN HALF OF THE REGION AS A
SERIES OF SHORTWAVES AND JET MAXES IN SOUTHWEST FLOW ALOFT WORK
WITH AN UNSTABLE AIRMASS AND...OF COURSE...TERRAIN. SHEAR VALUES
ARE NOT CONDUCIVE FOR SEVERE WEATHER...BUT WITH CAPE VALUES
PROGGED TO BE UPWARDS OF 400 OR 500 J/KG ACROSS PORTIONS OF THE
AREA AND LI VALUES OF -1C ACROSS MUCH OF THE REGION...CERTAINLY WE
COULD SEE AT LEAST SOME WEAK...SHORT-LIVED THUNDERSTORMS THIS
AFTERNOON/EVENING. THE CHANCE OF THUNDERSTORMS IS LOWER ACROSS THE
EAST DUE TO SOME CONVERGENT FLOW ALOFT. OUTSIDE OF
THUNDERSTORMS...MIXING THROUGH THE DAY SHOULD RESULT IN WEST TO
NORTHWEST WINDS GENERALLY IN THE 15 TO 25 MPH RANGE TODAY AS HIGHS
REACH THE 60S TO NEAR 70.

WEAK RIDGING LOOKS TO BUILD INTO THE REGION TONIGHT...SO THE
POTENTIAL FOR SHOWERS AND THUNDERSTORMS DIMINISHES SIGNIFICANTLY
THROUGH EARLY TUESDAY. PARTIAL CLEARING WILL ALLOW TEMPS TO BOTTOM
OUT IN THE MID 30S ACROSS THE WEST AND THE 40S ACROSS THE EAST
TONIGHT. MORE SHOWERS AND A FEW THUNDERSTORMS ARE POSSIBLE TUESDAY
AFTERNOON AND EVENING...ESPECIALLY ACROSS THE SOUTHWESTERN HALF OF
THE REGION AS SHORTWAVE ENERGY EJECTS NORTHEASTWARD OUT OF AN
UPPER LEVEL LOW IN THE GREAT BASIN...AND FLOW OVER THE BILLINGS
CWA REMAINS SOUTHWESTERLY. INSTABILITY WILL ALSO BE FAVORABLE FOR
SOME CONVECTION AS 850-500 MB LAPSE RATES ACROSS THE SOUTHWESTERN
HALF OF THE REGION ARE EXPECTED TO BE BETWEEN 7C AND 8C PER KM.
HIGHS TUESDAY WILL BE SIMILAR TO TODAY. STC

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

EXTENDED RANGE PROGGS IN GOOD AGREEMENT ON GENERAL PATTERN. CUT
OFF UPPER LOW OVER THE DESERT SW WILL LAY UNDER BROAD ANTI-
CYCLONIC FLOW FOR MUCH OF THE COUNTRY. 850MB TEMPS SUGGEST WE WILL
SEE SOME OF THE WARMEST TEMPERATURES OF THE SEASON THUS FAR BY
THURSDAY AND FRIDAY...WHILE STRONG SE SURFACE FLOW LEADS TO SOME
POTENTIALLY STRONG THUNDERSTORMS OVER THE EASTERN BORDER COUNTY
ZONES FROM MILES CITY TO BROADUS AND EASTWARD. THE RIDGE BREAKS
DOWN AROUND SATURDAY EVENING AS A TROUGH IN THE NORTHERN STREAM
MOVES THROUGH THE NORTHERN ROCKIES. THIS SHOULD LEAD TO A MORE
WIDESPREAD COVERAGE OF THUNDERSTORMS FOR THE WEEKEND.

THE WARMER TEMPERATURES AFTER MIDWEEK WILL RESULT IN AN INCREASE
IN HIGH ELEVATION SNOWMELT...SO AREA RIVERS AND STREAMS WILL
LIKELY SEE STEADY RISES LATE THIS WEEK. BT

&&

.AVIATION...

LOCAL FOG IS POSSIBLE BETWEEN 11Z AND 15Z FROM KBIL TO KMLS AND
BHK THIS MORNING. VFR CONDITIONS WILL OTHERWISE PREVAIL THROUGH
EARLY AFTERNOON BEFORE SCATTERED SHOWERS AND THUNDERSTORMS
DEVELOP. MOST OF THE THUNDERSTORM ACTIVITY WILL BE OVER OR NEAR
HIGHER TERRAIN THIS AFTERNOON AND EVENING WITH MOUNTAIN TOPS
OCCASIONALLY OBSCURED. BT 

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY TUE     WED     THU     FRI     SAT     SUN     
-------------------------------------------------------
BIL 067 044/067 046/071 048/080 051/083 052/076 050/073
    4/T 23/T    22/T    11/B    12/T    23/T    33/T
LVM 062 037/065 039/070 043/081 046/080 045/073 043/073
    5/T 35/T    32/T    12/T    22/T    24/T    43/T
HDN 069 042/069 046/074 046/081 050/084 052/079 050/075
    4/T 23/T    32/T    22/T    22/T    23/T    33/T
MLS 069 044/069 047/074 049/080 051/085 055/079 052/075
    2/T 22/W    12/T    22/T    22/T    23/T    33/T
4BQ 070 042/069 046/073 047/081 049/083 052/079 049/073
    2/T 22/T    42/T    32/T    22/T    23/T    32/T
BHK 068 043/066 045/071 047/077 050/081 053/078 053/074
    2/T 12/W    12/T    32/T    22/T    23/T    33/T
SHR 065 039/065 044/070 043/078 044/079 049/075 047/071
    4/T 33/T    43/T    22/T    22/T    23/T    32/T

&&

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

&&

$$
WEATHER.GOV/BILLINGS