Area Forecast Discussion
Issued by NWS Pocatello, ID

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202
FXUS65 KPIH 272051
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
251 PM MDT Mon Mar 27 2017

.SHORT TERM...A disturbance in splitting flow is working across
southeastern Idaho this afternoon. The southern portion of the
split has been working more southward through Nevada and Utah. So
far, surface temperatures are falling short of convective
temperatures needed for isolated thunderstorms to develop this
evening, plenty of cloud cover. There is a little instability in
the Eastern Magic Valley where clouds have scattered out, but this
is on the back side of the disturbance and low level winds are
northwesterly and not so favorable for thunderstorms. Left out any
mention of thunderstorms for this evening and trimmed rain amounts
back a touch as a result. By Tuesday morning there will be little
more than and isolated showers near Bear lake, otherwise a high
pressure ridge moves in with clearing skies until late Wednesday
afternoon or evening when a new disturbance edges into the Central
Mountains. RS

.LONG TERM...Wednesday through next Monday night. Cloud shield from
massive spring storm expected Wednesday, possibly with some
precipitation on the western edge of the forecast area, spreading by
Wednesday afternoon to a chance threat all the way to the ID-WY
border. The main precipitation is still expected Thu and Thu night,
with low elevation snow developing in the cold air towards the end
of the event. The splitting low makes Quantitative Precipitation
Forecasts a little low confidence, as it depends mainly on where the
split may occur and keep a dry area overhead. Also, floor of the
Snake River plain still has a chance of getting no snow, but right
now it appears more likely that it will get some. Expecting trace to
2 inches is the likely range. Fri afternoon and evening may now be
windy, but will have to see if this continues as Fri has not looked
the windy in previous model runs. Timing of a low after the Thu
storm is in disagreement between the GFS and the ECMWF. The ECMWF
keeps things much wetter, especially Mon; about the only agreement
is a mainly dry Sat. Thus GFS temperatures are much warmer beyond
Fri due to clear skies and strong insolation. Messick

&&

.AVIATION...Sky condition at most airdromes are more pessimistic
compared to reality, and so lightning may not show up today, just
showers, as temperatures stay fairly cool. Gusty west winds should
subside in the late afternoon/early evening, and skies should turn
clearer between midnight and 28/15Z. Do not perceive a fog threat
for the morning at this time, but this must be monitored as we are
barely out of the traditional fog season here. If wind decreases
more than expected, it could happen very easily. Messick

&&

.HYDROLOGY...The latest forecast for the Portneuf River does not
take it back to moderate levels later this week. Otherwise, there
are no changes to the current suit of warnings and advisories that
are out. RS

.PIH WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Tuesday morning for IDZ017>019-022>025-031-
032.

&&

$$



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