624
FXUS65 KBYZ 261532
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
932 AM MDT WED JUN 26 2019
UPDATE
MAY SEE SOME ISOLATED SHOWERS OVER THE MOUNTAINS AND NEARBY
PLAINS THIS MORNING AS SATELLITE AND RADAR SHOWING SOME WEAK
ECHOES TRACKING THROUGH. PROBABLY JUST SPRINKLES THOUGH. WE STILL
ANTICIPATE A BUSY AFTERNOON AND EVENING OF THUNDERSTORMS. LARGE
HAIL A DEFINITE THREAT ACROSS THE AREA. STRONGEST SIGNALS OF
HELICITY TRACKS OVER CRAZIES TO ROUNDUP, AND SEVERAL FROM SOUTHERN
BIG HORN INTO POWDER RIVER COUNTY AND SOUTHEAST CORNER OF MONTANA
LATE TODAY. CANNOT RULE OUT A TORNADO THREAT EITHER...ESPECIALLY
IN THE SOUTHEAST.
FOLKS SHOULD KEEP A CLOSE EYE ON THE SKY, AND AN EAR TO LOCAL
MEDIA FOR WATCHES AND WARNINGS. BE READY TO TAKE ACTION IF
WARNINGS ARE ISSUED. BT
SHORT TERM...VALID FOR TDY AND THU
TODAY IS DEFINITELY A DAY TO KEEP AN EYE TO THE SKY IF YOU HAVE
OUTDOOR ACTIVITIES, AND HAVE A PLAN TO GET TO SAFE SHELTER WHEN
STORMS APPROACH.
EXPECT THUNDERSTORMS TO GET GOING EARLY AFTERNOON OVER THE
SOUTHWEST MOUNTAINS AND PUSH NORTH AND EAST THROUGH THE AFTERNOON
AND EVENING, MAKING THE DAKOTAS BY MIDNIGHT. AS WE HAVE BEEN
DISCUSSING THE PAST FEW DAYS THE INGREDIENTS FOR SEVERE
THUNDERSTORMS HAVE ARRIVED IN THE AREA, WITH EASTERLY LOW LEVEL
WINDS BRINGING PLAINS MOISTURE AND ENHANCING SHEAR. CAPE VALUES
WILL PUSH OVER 1500 J/KG THIS AFTERNOON OVER MOST OF THE FORECAST
AREA, WHILE 6KM BULK SHEAR VALUES RANGE FROM 40 TO 60KTS, PLENTY
OF ENERGY AND SHEAR TO SUPPORT SEVERE THUNDERSTORMS. SOUNDINGS FOR
THIS AFTERNOON INDICATING HAIL AS THE MAIN THREAT WITH
THUNDERSTORMS TODAY, WITH SARS HAIL SIZE ALGORITHM POINTING
TOWARD 2 INCH DIAMETER HAIL BEING SUPPORTED BY THE STRONGEST
STORMS TODAY. AS A RESULT SPC UPGRADED THE AREA TO A SLIGHT RISK
FOR TODAY.
TIMING OF STRONGEST STORMS TODAY: LIVINGSTON 1-5PM,
BILLINGS/ROUNDUP 2-6PM, HARDIN 3-7PM, MILES CITY/BROADUS 6-10PM.
THREAT OF STRONG TO SEVERE STORMS DEVELOPS AGAIN FOR THURSDAY
AFTERNOON/EVENING. FOCUS OF STRONGEST STORMS IS FURTHER NORTH WITH
A JET STREAK THAT PUSHES INTO NORTH CENTRAL MONTANA THURSDAY
EVENING. THERE IS MORE OF A CAP IN PLACE TOMORROW ALONG WITH THE
LACK OF A STRONG DISTURBANCE TO KICK START STORMS, SO CURRENT
MODELS ARE KEYING IN ON AREAS ALONG AND NORTH OF A HARLOWTON TO
MILES CITY LINE FOR SEVERE STORMS. HOWEVER, CAPE VALUES INCREASE
FROM TODAY INTO TOMORROW WITH VALUES PUSHING ABOVE 2000 J/KG
THURSDAY AFTERNOON, AND SHEAR VALUES IN THE 40-50KT RANGE
PERSISTING. WHILE THERE IS A LACK OF A STRONG FORCING MECHANISM
THERE IS A DRY LINE DEVELOPING ALONG THE MT/WY LINE ALONG WITH THE
MOUNTAINS TO SEED CONVECTION. WHILE IT DOES'T LOOK LIKE THERE
WILL BE A LOT OF STORMS ON THURSDAY, ANY STORMS THAT DO MANAGE TO
GET GOING WILL HAVE PLENTY OF ENERGY AND SHEAR TO BECOME SEVERE.
SO, WILL NEED TO KEEP A CLOSE EYE ON TOMORROWS FORECAST AND WILL
SEE IF THE CAM MODELS KEY IN ON ANY OF THE WEAKER FORCING
MECHANISMS AS THEY PUSH INTO THE THURSDAY AFTERNOON/EVENING TIME
FRAME. CHAMBERS
LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE
UNSETTLED WEATHER PATTERN LOOKS TO PERSIST THROUGH THE EXTENDED
FORECAST PERIOD FROM FRIDAY THROUGH NEXT THURSDAY. EACH DAY WILL
SEE A CHANCE FOR SHOWERS AND THUNDERSTORMS IN THE AFTERNOON AND
EVENING. STRONG TO SEVERE STORMS ARE POSSIBLE AT LEAST FRIDAY,
WITH FRONTAL PASSAGE.
THERE HAS BEEN A SIGNIFICANT CHANGE FROM PREVIOUS MODEL RUNS THAT
WERE FAIRLY CONSISTENT OVER THE LAST FEW DAYS. UPPER LEVEL PACIFIC
LOW IS NO LONGER PROGGED TO LIFT DIRECTLY NORTHWEST INTO CANADA.
THE MODELS NOW STALL THE PACIFIC LOW OVER OREGON AND WASHINGTON
THROUGH MONDAY FOR THE GFS, WHILE THE ECMWF DOES NOT EVEN MOVE THE
LOW ONTO THE COAST UNTIL TUESDAY. EITHER WAY THIS POINTS TO
PERSISTENT SOUTHWEST FLOW ALOFT OVER THE REGION FROM FRIDAY
THROUGH TUESDAY. UNSETTLED SOUTHWEST FLOW PERSISTS THROUGH THE
REMAINDER OF THE PERIOD. THE GFS INDICATES CLOSED PACIFIC LOW
SHIFTING INTO WESTERN MONTANA TUESDAY, BEFORE OPENING UP AND
STALLING ONCE AGAIN. MEANWHILE, THE ECMWF KEEPS THE CLOSED LOW
TOGETHER AND GENERALLY STALLED ON THE PACIFIC COAST. EITHER WAY,
THIS POINTS CONTINUED UNSETTLED WEATHER.
THIS PATTERN WILL KEEP INSTABILITY, MOISTURE, AND JET FORCING
PRESENT TO GIVE CHANCES FOR STORMS THROUGHOUT THE EXTENDED
FORECAST PERIOD. TEMPERATURES LOOK TO STAY IN THE 80S INTO NEXT
WEEK, WITH A FEW 90S POSSIBLE.
MODELS ARE IN POOR AGREEMENT AS THEY TRANSITION TO A NEW
SIGNATURE, BUT THE PATH OF THE PACIFIC LOW INDICATED IN THE GFS IS
QUITE SIMILAR TO THE ONE ADVERTISED 6 OR 7 DAYS AGO, BEFORE
SHIFTING TO THE PERSISTENT NORTHWESTERLY TRACK THAT HAS BEEN
ADVERTISED OVER THE PAST FEW DAYS. LIKEWISE, ENSEMBLES SEEM TO LAG
WHEN THESE MODEL CHANGES OCCUR. SO FAR, AT THIS TIME, SEVERE
POTENTIAL APPEARS TO MUCH LOWER FOLLOWING FRIDAY FROPA, WITH
REDUCED SHEAR AND CAPE, BUT MODELS ARE IN FLUX AT THIS POINT. SO,
UNCERTAINTY IS A BIT HIGHER LATER IN THE PERIOD.
GILSTAD
AVIATION
EXPECT VFR THROUGH THIS MORNING. SCATTERED THUNDERSTORMS WILL
DEVELOP THIS AFTERNOON, AND THESE STORMS WILL BE CAPABLE OF
PRODUCING HAIL AND STRONG WINDS, ALONG WITH LOCALIZED MVFR/IFR
FLIGHT CONDITIONS. GILSTAD/JKL
PRELIMINARY POINT TEMP/POPS
TDY THU FRI SAT SUN MON TUE
-------------------------------------------------------
BIL 079 055/087 058/084 056/080 055/081 057/081 057/083
4/T 52/T 22/T 22/T 23/T 33/T 32/T
LVM 075 050/081 052/079 048/076 048/078 051/078 050/079
5/T 63/T 23/T 22/T 22/T 33/T 32/T
HDN 083 055/088 058/086 056/080 056/082 057/081 057/082
5/T 62/T 22/T 22/T 33/T 33/T 32/T
MLS 083 058/086 060/088 058/080 056/081 057/080 057/081
1/B 42/T 32/T 31/B 43/T 44/T 43/T
4BQ 084 057/088 060/091 058/083 057/081 057/080 057/081
2/T 61/U 21/U 21/B 33/T 54/T 43/T
BHK 081 057/082 060/088 058/080 055/079 056/078 055/079
2/W 62/T 22/T 21/B 33/T 44/T 43/T
SHR 083 052/089 055/090 053/082 053/082 054/081 054/081
2/T 31/B 11/U 22/T 43/T 44/T 44/T
BYZ WATCHES/WARNINGS/ADVISORIES
MT...NONE.
WY...NONE.
WEATHER.GOV/BILLINGS
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