480
FXUS65 KBYZ 160251
AFDBYZ
Area Forecast Discussion...Updated
National Weather Service Billings MT
851 PM MDT Sun Jul 15 2018
.UPDATE...
Main update was to shrink pops a bit towards the southern
mountains and foothills this evening and overnight. Shortwave
energy was tracking a bit farther south with isolated showers and
thunderstorms farther south as a result. Have also adjusted sky
cover and temperatures to current trends. The rest of the forecast
remains on track and the previous forecast discussion and an
updated aviation discussion are below. STP
&&
.SHORT TERM...valid for Mon and Tue...
Surface high pressure currently sitting over eastern Montana
providing a cooler day today compared to the last couple. Low
level flow was easterly and this providing a bit of upslope, and
thus seeing some cumulus develop along the foothills and over the
mountains. Weak shortwave energy progged across southern Montana
and northern Wyoming this evening, and this should be enough to
generate a few showers and thunderstorms. Both global and high
resolution models were consistent in confining the activity over
the mountains and foothills, with a hint at some spreading out
into far southeast Montana.
Monday will be a little warmer. The surface high slides southeast
and brings the low level flow back to the southeast, allowing for
return moisture. Precipitable waters climb above an inch in the
southeast, with nearly an inch everywhere else. A shortwave trough
kicks out of Oregon and slowly enters western Montana, with the
leading edge nosing into western and southern zones. This will
initiate a good chance of showers and thunderstorms as this
system moves across. Highest PoPs on Monday will be over western
and southern zones, with PoPs spreading east Monday night.
The system kicks into central Montana Tuesday, and this will
spread the most likely locations for convection into southeast
Montana. The ECMWF was a little slower and this would pull the
good chance of convection into the central zones. PWATs will rise
to around an inch and a third over southeast Montana, with weak
shear. Capes should be able to reach around 1000 j/kg Tuesday
afternoon and evening. Am expected much better coverage of
convection across central and eastern zones, with pulsing storms.
Shear is projected to be weak, so should not see organized strong
storms. Will however, have the ability to see some pulsing hail.
Storms will be slowing moving, and with high PWATs, the risk of
heavy rain is real. Will continue to advertise that in a HWO and
weather story. TWH
.LONG TERM...valid for Wed...Thu...Fri...Sat...Sun...
Extended forecast period appears warm and dry throughout, with
exception of occasional isolated showers/thunder in high terrain.
Upper level ridging will prevail through the bulk of the period.
Temps will be a few degrees above normal, with highs in the low
90s through the period.
The only chance for weather at this time appears to be tied to
exiting upper level trof, with lingering showers and general
thunderstorms over eastern MT. Meanwhile, the rest of the region
will see a drying trend as the upper ridge builds in.
There is some indication of the ridge breaking down at the end of
the period, with a cold front crossing the region on Sunday. This
FROPA appears mainly dry, and has been pushed further down the
line in last few model runs. Therefore have continued with
inherited mainly dry forecast. AAG
&&
.AVIATION...
VFR will dominate overnight into Monday morning. An isolated
shower or thunderstorm possible along the WY/MT border. borsum
&&
.PRELIMINARY POINT TEMP/POPS...
Mon Tue Wed Thu Fri Sat Sun
-----------------------------------------------------------
BIL 060/087 063/084 061/092 062/091 061/092 063/092 062/092
12/T 34/T 51/U 10/U 11/U 10/U 10/U
LVM 055/083 056/082 054/088 052/088 051/090 054/090 053/090
13/T 45/T 20/U 10/U 11/U 10/U 10/U
HDN 059/089 062/086 059/092 060/091 060/093 062/092 063/092
12/T 35/T 51/U 10/U 11/U 10/U 00/U
MLS 059/088 063/087 063/088 062/090 062/090 065/092 065/092
00/U 13/T 61/B 10/U 01/U 10/U 00/U
4BQ 062/088 063/086 061/087 061/090 060/091 064/093 064/093
21/U 25/T 61/B 10/U 01/U 10/U 10/U
BHK 057/084 057/084 061/082 059/087 058/086 061/089 061/089
01/U 01/B 52/W 10/U 01/U 11/U 10/U
SHR 057/086 057/084 056/090 057/090 054/092 058/093 058/093
23/T 45/T 41/U 10/U 11/U 10/U 10/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
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