Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Billings Montana
905 am MDT sun may 3 2015
weak echoes on radar from S of kbil through southeast Montana this morning
were mainly middle clouds per surface observations...with possible
sprinkles. Web cams showed dry conditions.
Sprinkles/middle clouds were being induced by weak right-rear jet
quadrant upper divergence which will continue through the evening
from the 90 knots jet to the north of the area. New WRF showed middle-level
frontogenesis over the area of radar echoes into the afternoon.
Chance of sprinkles will end by 18z as frontogenesis moves out.
Isentropic lift increases over western areas by 00z tonight.
Trimmed back the sprinkles to better fit the current radar echoes
and removed probability of precipitation from the NE bighorns this morning. The afternoon
probability of precipitation over the mountains were fine and no mention of thunder made
sense given the low convective available potential energy on the sref...and rap soundings.
Temperatures and dewpoints looked good today. Adjusted sky cover
based on current satellite...and wind speeds based on latest
guidance. Klvm tends to become gusty with an east wind.
Low-level southeast flow increases tonight and Monday while isentropic
lift continues over the area. Probability of precipitation were in good shape. Arthur
Short term...valid for today and Monday...
Quiet end to the weekend expected as a westerly flow aloft will
continue over the forecast area today. Satellite showing an area
of clouds across the southern and eastern portions of the state
with clearing just to the west of our area. Expect these clouds to
move east allowing for partly sunny skies to develop from west to
east today. Radar has been showing some returns from about Big
Horn County east to the Dakotas. However...believe most if not all
of this is virga as temperature/dewpoint spreads are quite high
and cloud bases are around 11k feet. Temperatures today will be a
good 10 degrees cooler as a result of the front that moved through
last evening. Most areas will see highs in the 60s which is normal
for this time of year.
An upper low and trough approach the Pacific northwest coast late
in the day Monday. This will allow the flow to buckle somewhat
resulting in weak ridging building across our area...as well as a
southwest flow aloft. A weak disturbance will move northeast out
of the Great Basin area during the afternoon and evening bringing
a slight shower and isolated thunderstorm chance to our far
western areas with the best chances over the absaroka/beartooth
and Big Horn Mountains and adjacent foothills. As the disturbance
moves east...the better shower chances will shift across our
southeast counties Monday night. Temperatures Monday will warm
back to above normal with readings in the 70s...except for some
60s out toward the Dakota borders. Hooley
Long term...valid for Tuesday...Wed...Thu...Fri...Sat...
Models have continued the same general pattern in the
long term...wetter and cooler. Tuesday the low over the Pacific
will begin to move along the coast as it digs south. This will
bring moist southwest flow into the area. The flow will generally
be unsettled as several impulses of energy move through the flow.
This will give the area a shot at rain...but mostly in the
mountains. The best chances for rain will come towards the weekend
as the low in the Great Basin lifts into Wyoming. This will bring
the greatest energy moving through coincident with some decent
forcing. There continues to be some timing and placement issues
between the models with the precipitation...so have not gotten too
specific. With the increased moisture and cloudiness...continue
to expect temperatures to be near normal...generally in the 60s
for highs. Reimer
VFR conditions will continue to prevail over the next 24 hours.
Winds will generally be light throughout the day. Some showers
will continue to be possible in the mountains with localized
mountain obscuration. Reimer/frieders
Preliminary point temp/pops...
Today Monday Tuesday Wednesday Thursday Friday Sat
bil 065 045/075 050/076 047/065 045/051 040/053 041/058
1/b 11/b 12/T 54/T 34/west 44/west 55/west
lvm 066 038/074 043/075 041/062 039/047 035/049 036/059
2/west 12/T 23/T 55/T 45/west 44/west 55/west
hdn 067 043/078 045/079 046/067 044/054 040/056 040/062
1/b 21/b 12/T 43/T 34/west 33/west 44/west
mls 066 045/073 049/076 050/067 044/059 041/060 042/060
0/b 11/north 11/b 44/T 33/west 33/west 34/west
4bq 066 043/070 046/074 048/066 045/059 042/056 040/060
1/b 32/west 11/north 45/T 33/west 33/west 44/west
bhk 064 039/067 045/070 047/064 043/058 038/057 038/056
1/b 12/west 11/north 46/T 33/west 22/west 34/west
shr 065 043/072 044/072 044/063 041/054 038/055 039/057
2/west 32/T 22/T 44/T 34/west 44/west 55/west