Area Forecast Discussion
Issued by NWS Billings, MT
FXUS65 KBYZ 252112
Area Forecast Discussion
National Weather Service Billings MT
312 PM MDT WED MAY 25 2016
.SHORT TERM...valid for Thu and Fri...
Scattered showers w/ some thunderstorms have developed since
late morning and are courtesy of diurnal heating and cyclonic
flow plus cool air aloft. With low freezing levels in place there
have already been reports of small hail from the stronger cells,
and this will be common over the next few hours, though
instability is too low/shallow to produce severe weather. Upper
low which has been in southern Saskatchewan for several days is
beginning to sag southward. Area of PV will rotate through our
northern areas later tonight and this should be a focus of shower
activity, and perhaps some late night thunder, overnight into
Upper low will shift slowly east to western ND tomorrow afternoon
and evening, and the persistent cyclonic flow aloft will result in
more diurnal showers and isold tstms again on Thursday. Greatest
chances will be in our west as cooler air on back side of low will
provide some stabilizing for our east.
A period of shortwave ridging should bring quieter weather late
Thursday night into Friday morning. Models in good agreement with
this timing, so have lowered pops a bit. By Friday afternoon and
evening, ascent from next Pacific trof will bring our next round
of afternoon and evening showers and thunderstorms, especially for
our west. This convection should also be non-severe but given
synoptic ascent and lifted indices to near -2C or -3C, storms
could become a bit stronger in our west near places such as
Livingston and Harlowton.
Temps will remain at or a little below normal the next two days,
with Friday being the warmer courtesy of aforementioned ridging.
.LONG TERM...valid for Sat...Sun...Mon...Tue...Wed...
An upper low will gradually lift north and east through Tuesday
with a few shortwaves rotating around the parent low affecting
the area. One of these shortwaves will swing through the area on
Saturday, continuing shower and thunderstorm chances. Weak ridging
behind the shortwave will bring a fairly dry Sunday to much of the
area with just a slight chance for showers and thunderstorms.
Another shortwave is progged to approach and slowly propagate over
the area Sunday night through Tuesday bringing additional shower
and thunderstorm chances, although model differences do exist. The
ECMWF is much more progressive and drier with the wave and the GFS
is slower and wetter. There continues to be enough instability
around to include showers and the mention of thunder in the
forecast every afternoon and evening. At this point, the best
chance for stronger thunderstorms would be across the east on
Monday, although this could change as there is still uncertainty
in model solutions.
Models prog a ridge to build over the west starting late Tuesday
into Wednesday, potentially bringing drier weather to the region.
Temperatures will continue to run near to slightly below normal. STP
Scattered showers were found across a large portion of the area
this afternoon with isolated thunderstorms generally south and
east of KBIL. Showers/thunderstorms will continue into the
evening as an upper low spinning over southern Saskatchewan keeps
the area under cyclonic flow. VCSH will be possible through the
night as the upper low begins to drift closer to the area. MVFR
conditions and small hail are possible with the thunderstorms.
Mountains will be obscured at times through tonight. STP
.PRELIMINARY POINT TEMP/POPS...
Thu Fri Sat Sun Mon Tue Wed
BIL 046/068 046/070 047/066 046/071 048/070 047/066 045/071
33/T 23/T 43/T 32/W 34/T 43/T 31/B
LVM 041/065 041/065 040/061 040/068 041/066 041/064 039/068
34/T 35/T 54/T 32/T 34/T 43/T 32/T
HDN 044/070 043/072 047/070 045/074 048/074 046/069 044/073
33/T 22/T 33/T 32/W 34/T 43/T 31/B
MLS 048/068 046/073 049/072 049/075 052/076 051/068 047/073
44/T 22/T 23/T 32/T 34/T 44/T 41/B
4BQ 044/070 043/072 044/071 045/075 048/077 046/069 044/073
23/T 22/T 24/T 32/T 34/T 44/T 41/B
BHK 044/067 043/070 045/071 045/073 046/074 047/067 043/071
24/T 22/T 14/T 32/T 34/T 44/T 43/W
SHR 041/067 040/069 043/067 041/072 043/073 043/066 040/071
33/T 22/T 23/T 42/T 34/T 43/T 31/B