Area forecast discussion
National Weather Service Pocatello Idaho
214 PM MDT Sat may 25 2013
Short term...tonight through Monday night. Upper trough over
Pacific northwest with shortwave energy riding through central
mountains this afternoon. Band of cirrus covering eastern half of
forecast area with weak convection bubbling over the central mountains
and portions of the eastern Highlands per Sat imagery. Shortwave
energy pushes well northeast of forecast area into Montana this
evening with most convection ending around sunset. Reinforcing
shortwave circulation along 130w steepens trough and ejects across
the Great Basin during the day Sunday. Air mass slightly more
unstable in eastern Idaho on Sunday afternoon so expect convection
to be slightly more widespread. Trough axis lifts through the
region Sunday evening and overnight as a sharp negative tilt
trough. NAM sharper with this feature than the GFS...but GFS
closes circulation off over central Montana by midday Monday.
There appears to be a break late Monday over eastern Idaho with
precipitation returning Monday night. Another strong negative tilt
trough rapidly slides across the Great Basin. Timing on both the
GFS holds the bulk of the precipitation west of eastern Idaho until
during the day Tuesday...but have increased probability of precipitation in the western
third of the forecast area per slightly faster NAM. Dmh
Long term...Tuesday through next Sat night. Longwave pattern keeps
troughing over the Pacific northwest which moves over western Idaho
then Delaware-amplifies to a weak west-southwesterly airflow. Thus the
good agreement in terms of a very wet pattern developing in the
forecast area by Tuesday night and continuing through at least Thursday.
Significant rain...including some high elevation snow that will
likely melt in a day...is possible. Combined with
heating...thunderstorms and flash flooding are a potential with a
closed low moving through the forecast area during this time.
Clearing expected on Friday with warming returning Sat. For the Snake
River Plain mild overnight lows in the 40s and afternoon highs only
in the 60s with the extensive cloudiness. The closed low may pack
something of a punch with winds...mainly in the Snake River
Plain...25 to 35 miles per hour with higher gusts on Wednesday and Thursday afternoon are
possible. Messick
&&
Aviation...middle level ceilings develop during the late evening with
winds becoming lighter and not as gusty. Good VFR throughout the
period with little risk of -shra/-tsra. Messick
&&
Pih watches/warnings/advisories...
none.
&&
$$
