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Area forecast discussion
National Weather Service Grand Junction Colorado
302 PM MDT Tue Jul 25 2017

Short term...(tonight through Wednesday night)
issued at 302 PM MDT Tue Jul 25 2017

Precipitable water is climatologically maxed out this afternoon across the
Utah/Colorado border. We had one batch of rain move north out of
the cwa by noon with some clearing across the SW in the wake of
this rainfall. This heating...and stronger winds aloft associated
with an organized wave moving northward across central Utah is
creating conditions favorable for stronger storms. Small
hail...heavy rainfall and possibly some gusty winds will be
possible with these storms as they move northward out of southeast
Utah into west central and northwest Colorado through the evening.
Widespread showers and storms will also continue over the
remainder of the region through the early morning hours this wave
moves through and forces the main moisture plume eastward. Do
expect a decent downturn in the precipitation by sunrise as
subsidence behind this wave kick. Some drier air will be advecting
in from the west on Wednesday but deeper moisture remains over
our southern mountains and when combined with a bit more
sunshine...showers and storms should become likely over the hills
by early afternoon. The eastern valleys should see some storms
drift in through the late afternoon...with drier air and less
focus limiting the storms in the western valleys. Temperatures
will bump up a bit on Wednesday with less cloud cover but still
remain slightly below normal.

Long term...(thursday through tuesday)
issued at 302 PM MDT Tue Jul 25 2017

By Thursday the upper high will begin to migrate back to the west
as energy digs across eastern Continental U.S.. this will reduce the
northward extent of the monsoonal plume but keep it located to the
south of our border. We will keep afternoon storms in the
forecast but with a gradual downturn Thursday into Friday. The
models have changed due to a stronger trough located over the left
coast going into this late week period. Earlier trends had the
high reforming back over the Great Basin. However now this high
is centered back over our County Warning Area by Saturday and suppressed a bit to
the south due to stronger westerly flow across the US/Canada
border. This seems to allow a bit more monsoonal moisture to seep
under the ridge and begin and upward trend to storms going into
the weekend and early next week. Expect seasonal temperatures
through the long term period.


Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 1101 am MDT Tue Jul 25 2017

A pair of disturbances continued to generate showers and just a
few embedded thunderstorms in a broad swath stretching from Lake
Powell north-northeastward across east-central Utah and northwest
Colorado. As temperatures rise expect shower/thunderstorm activity
will spread across the remainder of eastern Utah and western
Colorado, initiating first over the higher terrain. The atmosphere
is just soupy with moisture according to morning sounding data so
chances are high that all taf sites will experience showers from
time to time between 18z through 04z this evening. Showers and
thunderstorms will be capable of generating brief MVFR visibility
with ceilings falling below ils breakpoints for some sites. Heavier
cells may produce brief IFR conditions as well. Showers and
thunderstorms will decrease, but not entirely diminish overnight.
Chances are reduced for additional activity during the
overnight/Wednesday morning period, but kril, kege, and kase may
experience periods where ceilings are below ils breakpoints.


Gjt watches/warnings/advisories...
Colorado...Flash Flood Watch until midnight MDT tonight for coz001>014-

Utah...Flash Flood Watch until midnight MDT tonight for utz022>025-


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