Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 210916

Area Forecast Discussion
National Weather Service Pocatello ID
316 AM MDT Tue Mar 21 2017

.SHORT TERM...Today through Thursday night. A big low pressure
system continues to sit off the west coast. This is sending rounds
of showers through the region. A cold front will arrive tonight.
Best chances for showers will be along the front. Thunderstorms
are possible as well as models showing weak instability ahead of
the front. NAM appears very convective happy with its rainfall
amounts tonight so leaned heavily on the GFS. The front is expect
to stall across the southeast highlands late tonight. Expect
breezy conditions ahead of the front, probably below wind advisory
levels though. The front will remain the focus of activity for
Wednesday and Thursday as rounds of showers run along the front.
Models show enough instability developing along the front for a
few thunderstorms to remain possible especially during the
afternoon and evening hours. The low pressure system will move
onto the central California coast Wednesday afternoon and move
through central Nevada and into northern Utah Wednesday night.
This will allow the front to push westwards somewhat towards the
Snake River Plain during this time. By Thursday afternoon the low
moves into Wyoming which will drag the front into Wyoming Thursday
night. Showers will gradually come to an end from west to east.
Snow levels through this event will stay relatively high.
Generally above 8000 feet Today and Tonight, with an inch possible
along Galena Summit. Snow levels fall to around 7000 feet
Wednesday and Thursday, with lower snow levels across the central
Idaho mountains. However, see very little if any moisture back
across central Idaho during this time. As a result, very little
snowfall really through most of the region, perhaps an inch or two
across the peaks of the southeast highlands, but not seeing any
impacts to mountain passes.


.LONG TERM...Friday through Monday night. The largest storm of the
week may push into the extreme western zones Friday afternoon, but
would expect most of the precipitation to move in Friday night and
continue through the rest of the period. The heaviest
precipitation period should be Saturday. The strong cooling behind
this storm means snow down to 5000 ft elevation or so for eastern
Idaho. Fortunately, the low that meanders around the Great Basin
during this time is not well organized and not expecting any wind
event with this feature. May need a Winter Weather Advisory for
the snowfall on Sat/Sat Night. With all the cloudiness, and with a
mild air mass overhead, temperatures are right around climatic
normals after Friday. Messick


.AVIATION...Middle and high cloudiness will continue to move
across, with an incoming low bringing precipitation threats
during the evening to the two western airports, then around
22/06Z spreading eastward and bringing precipitation to KIDA,
KPIH, and KDIJ. There is some potential for marginal VFR
conditions due to CIG during the late night hours. Also, expect
gusty wind this afternoon with the approaching low. Thunderstorm
threat continues for the next couple of days. Messick


.HYDROLOGY...Emergency Management across the region have reported
mostly status quo or worsening conditions. Thus have continued all
areal flood advisories plus added a few more in particular trouble
spots. Area web cams and/or emergency management indicate snow pack
continues to ripen, and have added additional areas to areal flood
watch in response to these concerns. Will likely trim portions of
the flood watch in the Snake Plain at next update. With respect to
rivers, most gages showing modest rises in response to runoff.
Portneuf remains above flood at this time, so warning was continued
there. Bear River could reach flood stage by Wednesday night, so
issued watch for that region. Remainder of rises covered by blanket
river statement at this time. DMH


Thursday morning for IDZ017>019-021>025-031- 032.


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