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Area forecast discussion
National Weather Service Pocatello Idaho
245 PM MDT Thu Sep 19 2019

Short through Monday. From current radar imagery,
precipitation is along our western borders, particularly across
the central mountains with snow levels starting around 8000 to
8500 feet. Expect breezy conditions mainly today and to a slight
degree Friday afternoon. Winds are not going to be as near as
strong as the Monday system. Look for remaining precipitation
amounts with this system of 0.10 to around 0.40 inch, with
localized higher amounts, in the central mountains. Valleys will
get around 0.05 to 0.30 and with mountains elsewhere receiving
0.20 to 0.50 with the Island Park area seeing the higher amounts
of around 0.50. Some areas may see brief and light snow as low as
around 7000 to 7500 feet with heavier bands of precipitation.
Areas in the central mountains could see additional 1 to 2 inches
of snow with locally higher amounts around 3 to 4 inches through
Friday morning above 8000 feet. Burn areas should be watched,
particularly in the central mountains. However, precipitation
continues to be light overall as well as spread out through
several hours.

Brief high pressure ridging builds in late Saturday into Sunday.
With clearing and overall light winds, Saturday morning looks to
be cold. Portions of the Snake River Plain and eastern Magic
Valley may need a frost advisory Saturday morning depending if
clouds clear out or remain. Currently models show cloud cover over
the northern upper snake Plain. Mountain areas will certainly see
freezing temperatures Saturday morning.

From Sunday on, models continue to show change and disagreement.
The GFS model continues to hold on to a weak, open trough with
light to moderate precipitation early Monday morning. The European model (ecmwf)
model drops a low just west and south of our area on Monday with
little precipitation over our western areas with slightly higher
amounts over our extreme northern areas. The European model (ecmwf) model shows
little, if any, precipitation over our eastern areas.

Long term...Tuesday through Friday. Both models show our area in
a west northwest upper level flow with overall high pressure
building back into our area bringing warmer and drier conditions
Tuesday and, particularly, Wednesday. Thursday the flow changes to
a southwest flow ahead of system that starts to move over our area
late Thursday into Friday.

Look for temperatures around 5 to 10 degrees below normal today
and then drop 10 to 15 degrees below normal Thursday and, to a
lesser degree, Friday. Morning lows Saturday morning are expected
to be in the low to mid thirties across portions of the Snake
River Plain and eastern Magic Valley. Temperatures start to
approach normal again by Sunday before potentially dropping below
normal Monday and then rise to near normal Tuesday and then near
normal Wednesday. Tw


Aviation...rain is not progressing rapidly east. Have it starting this
afternoon in sun, around midnight in byi and Friday morning at pih,
Ida and dij. Drop sun to MVFR after midnight tonight through
Friday morning and dij to MVFR Friday morning. Keep other three
sites with VFR ceilings although the potential to drop to MVFR in
heavier rain Friday exists.


Fire weather...main impact will be rain and snow at high elevations through Friday
evening. Main impact early tonight will be zones 475, 476 and 422
which will then spread east late tonight and Friday. Heaviest
precipiation Friday will be in extreme eastern zones. Temperatures
will remain quite cool through Friday. Expect drying west to east
Saturday with temperatures beginning to warm with Sunday expected to
be dry and warmer during the day with the precipitation beginning
Sunday evening through Monday with the next storm system. Although
this system looks much weaker with little precipitation expected.
Dry and mild weather is expected Tuesday and Wednesday with the next
system and potential precipitation Thursday.


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