Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Billings Montana
926 am MDT Monday Jul 6 2015
Made a few adjustments to the forecast for today with this
mornings update. Northeast surface flow continues to hold a
stratus deck across our western half but satellite is showing this
to be breaking up some...especially across our northeast counties.
As a result...sky cover has been adjusted. Satellite and observation still
show some areas of fog near the mountains and foothills locations.
Haze is also being reported and observed across some areas. In
addition...removed precipitation chances across the central and western
areas as radar is clear and lowered probability of precipitation to just a slight shower
chance for the morning across the far east. Updated forecast for
the above has been sent. Hooley
Short term...valid for today and Tuesday...
Shortwave associated with central Canadian upper low...was seen
on water vapor imagery early this morning moving through NE Montana.
This energy was combining with lift from the right-rear quadrant
of an upper jet to bring widely scattered showers to the eastern
part of the forecast area. Hrrr has a decent handle on the
showers and showed them increasing in coverage over southeast Montana around
12z. Rap soundings showed saturated low to middle layers from kbil S
and east this morning...so went with slight chance probability of precipitation around kbil
to chance probability of precipitation from Rosebud County east and over Sheridan
County...where the best lift from the wave is expected. Expect
stratus over the area this morning based on soundings...then
soundings become inverted-v in the afternoon with mixing to just
below 700 mb. There will be low chances of mountain thunderstorms
this afternoon with some instability indicated by the sref. Light
low-level winds will keep smoke in the area through the day.
Expect highs in the upper 60s to middle 70s based on the above.
Heights begin to lower tonight as the area remains under cyclonic
flow. Models continued to support slight chances for thunderstorms
in the mountains. Kept smoke in the grids due to the continued
light low-level flow and decreased mixing.
A weak cold front will move S through the area on Tuesday and an
inverted trough will set up over the southeast zones. Shortwaves will
continue to move through the cyclonic flow with a strong wave
moving east through Wyoming. The Wyoming wave will help push monsoonal moisture
north into the forecast area. After morning mountain probability of precipitation...have
increased coverage of probability of precipitation across the area in the afternoon given
the weak frontal passage...inverted trough...increasing moisture
and the sref showing possibly 500 j/kg of surface cape. Similar
pattern persists for Tuesday night as cooler air continues to filter S
into the area so increased coverage of probability of precipitation. Better mixing on Tuesday
will support highs in the lower 80s. Shear and convective available potential energy look too weak
Tuesday/Tuesday night to support severe weather. Arthur
Long term...valid for Wednesday...Thu...Fri...Sat...sun...
The long term forecast period will be highlighted by warm weather
and some chance of showers and thunderstorms...especially Friday
into Saturday. It/S during that time frame that model guidance is
consistent in showing a 500-mb low lifting out of California and
shearing into an open wave by the time it reaches Montana. The 00
UTC European model (ecmwf) trended toward the last several GFS solutions by having
that wave Cut Through broad ridging aloft...contributing to weak
deep-layer wind fields despite southwest flow aloft. If that does
occur...the risk of severe storms will be relatively low.
By late next weekend and into the following week...global models
suggest the sub-tropical ridge will intensify and shift westward
into the southern rockies. That may incite a more bonafide warmup
over southern Montana and north central Wyoming. The 00 UTC GFS and European model (ecmwf)
suggest the ridge will amplify enough to keep most storm activity
relegated to northern Montana by Sunday and Monday...though any subtle
shift in the ridge/S amplification could change that. Schultz
MVFR to IFR conditions in low clouds and in some cases fog will
continue across south central Montana and north central Wyoming until middle to
late morning. Meanwhile...MVFR ceilings are possible along with a
few showers and light smoke in southeastern Montana this morning. VFR
conditions will prevail area-wide by this afternoon and evening...
though some light smoke may continue in southeastern Montana.
Preliminary point temp/pops...
Today Tuesday Wednesday Thursday Friday Sat sun
bil 074 056/081 059/080 058/088 062/090 062/088 062/091
0/b 02/T 22/T 12/T 23/T 32/T 21/b
lvm 075 050/080 051/079 051/085 055/087 056/084 054/088
0/b 14/T 33/T 23/T 23/T 33/T 31/b
hdn 076 056/084 057/083 057/091 060/093 060/091 060/093
1/b 03/T 22/T 12/T 23/T 32/T 21/b
mls 073 055/082 058/082 059/090 063/095 064/091 063/090
2/west 02/T 22/T 11/u 22/T 23/T 22/T
4bq 073 055/081 057/082 058/088 063/094 063/090 062/090
2/west 03/T 42/T 11/u 22/T 22/T 22/T
bhk 070 052/077 055/079 055/085 061/093 061/089 061/087
2/west 03/T 32/T 11/u 22/T 23/T 22/T
shr 070 052/078 053/077 054/084 056/087 056/086 056/089
2/west 13/T 42/T 22/T 23/T 22/T 21/b