Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 170012

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
612 PM MDT Sun Jul 16 2017

.SHORT TERM...(Tonight through Monday night)
Issued at 253 PM MDT Sun Jul 16 2017

High pressure centered over NV will begin to elongate across the
Four Corners over the next 24 hours. This will establish light
zonal flow across the region ending the north to south afternoon storm
track we have seen over the last couple of days. As anticipated,
precipitable water values just haven`t dropped much and continue
to remain plenty sufficient for afternoon convection. Brief heavy
downpours and gusty winds will be possible with storms over the
mountains each afternoon. The NAM continues to indicate a weak
disturbance brushing NE Utah and NW Colorado Monday, which should
make showers and thunderstorms more likely across this area
through the morning and afternoon.

.LONG TERM...(Tuesday through Sunday)
Issued at 253 PM MDT Sun Jul 16 2017

The center of high pressure becomes a little more round and
organized midweek and begins to shift eastward thanks to an
oncoming closed low into the Pacific NW. This pattern shift will
allow monsoonal moisture to increase clockwise into the Four
Corners region. Dewpoints are forecast to rise into the mid 50s by
late week with afternoon showers and thunderstorms more expansive
in coverage. CAPE between 1000 and 1500 J/kg and and lapse rates
near or in exceedance of 8 C/km should allow for more strong
storms to develop in the afternoons... focused on the San Juans each
afternoon through Wednesday. 12z model runs indicate the
stormiest days of the week across much of western Colorado look
to be late in the week, either Thursday or Friday afternoon, with
heavy and potentially excessive rain and frequent lightning being
the biggest threat with these storms.


.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 611 PM MDT Sun Jul 16 2017

Scattered showers and thunderstorms will continue, mainly over the
higher terrain this evening before dissipating just ahead of
midnight. This activity is unlikely to impact TAF sites, therefore
expect VFR conditions with CIGS above ILS breakpoints through
midday Monday. Showers and thunderstorms are expected to redevelop
over the higher terrain after 18Z on Monday, but storms are
unlikely to move over TAF sites. However, outflow winds to 40 MPH
are possible.






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