Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 242356

Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
556 PM MDT Wed May 24 2017

Issued at 550 PM MDT Wed May 24 2017

Updated pops for rest of this evening through Thursday as some
showers are already moving into the region. Convection looks a
little more widespread on Thursday, so increased coverage and
chances through Thursday evening and introduced thunderstorm
mention everywhere Thursday afternoon into early evening.


.SHORT TERM...(Tonight through Thursday night)
Issued at 404 PM MDT Wed May 24 2017

Winds are still forecast to increase tonight as a cold front
drops southward toward Utah and Colorado. Down valley flow will be
enhanced Thursday morning as these winds translate to the surface
from mid and high levels. By late Thursday morning, winds will
become westerly across the region and high clouds will have
increased across eastern Utah and western Colorado...with lower
layers of clouds increasing across NE Utah and NW Colorado with
rain showers expected to develop across these areas by noon
Thursday. Showers are expected to continue across the region
through the day Thursday and drop southward as the front remains
stalled but cooler air protrudes southward. Convective variables
indicate that thunderstorms will be possible Thursday as
well...aided by lapse rates being higher along the southern
periphery of the cloud shield. CAPE values are forecast to max out
around 1000 J/kg with 35 kts of 0-6 km bulk shear which is plenty
of energy for a few good storms Thursday afternoon.

.LONG TERM...(Friday through Wednesday)
Issued at 404 PM MDT Wed May 24 2017

By Friday night, the trough associated with the stalled front
across the region will begin to progress through the area. This
trough is expected to produce showers and thunderstorms as it
passes through and bring enough dynamics to bring some
precipitation to many of the valleys with potentially the
exception of the Four Corners valleys which may be protected by
the San Juans. Forecast models are still indicating a change to a
ridging pattern over the western US with a large amplitude ridge
developing starting on Sunday. This pattern continues throughout
the work week...with forecast models still indicating a closed low
developing over Baja CA undercutting the ridge but remaining
nearly stationary throughout the week. Diurnally induced showers
and thunderstorms will be possible each afternoon next week.


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 551 PM MDT Wed May 24 2017

Mid level cumulus clouds are in place over the forecast area this
afternoon with widespread gusty winds. The wind gusts are
anticipated to diminish this evening and drainage winds will then
dominate through the overnight hours. Otherwise expect VFR
conditions through at least Thursday morning. An approaching front
will bring a threat of showers and thunderstorms to the terminals
Thursday afternoon with increasing and gusty winds.


Issued at 404 PM MDT Wed May 24 2017

A cold front will be moving south across western Colorado tonight
and Thursday. The front is expected to stall north of the San Juan
Mountains, with scattered showers developing along and north of
the front. Across the southern valleys, especially across
Colorado Fire Weather Zone 207 and Zone 290, gusty southwest to
west winds are expected Thursday afternoon and evening. With the
front stalled to the north, expect temperatures to remain above
normal with relative humidity values dropping below 15 percent for
several hours. With winds in place, low humidities and critical
fuels, Red Flag Warnings are in effect from noon Thursday through
the early evening hours. North of the San Juans, scattered to
numerous showers are expected with a cooler air mass in place,
keeping relative humidity above the 15 percent threshold.


CO...Red Flag Warning from noon to 7 PM MDT Thursday for COZ207-290.



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