Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 192036

Area Forecast Discussion
National Weather Service Grand Junction CO
236 PM MDT TUE JUL 19 2016

.SHORT TERM...(Tonight through Wednesday Night)
Issued at 230 PM MDT Tue Jul 19 2016

In the large scale, an upper Low is spinning off the Washington-
Oregon coast and the subtropical High is on the southern plains.
This is producing a moist SW flow over the forecast area through
the work week. Precipitable water was measured at 1.22 inches on
the morning sounding, which is much above normal. Afternoon storms
are being driven by orographic lift, marginal instability, and low
shear environment. Thus storms are expected to be of the pop and
drop variety. Outflow boundary clashes will likely keep storms
going through the night. In addition a weak disturbance analyzed
over the Mogollon Rim this afternoon will move to near the Four
Corners this evening providing some additional forcing there.

Wednesday a larger wave that was in NW Chihuahua this afternoon
will work over the area. This looks to enhance thunderstorm
chances along and south of a line from Lake Powell to Steamboat
Springs. Storm coverage drops to isolated after midnight
Wednesday with no additional forcing evident.

The deep moisture, clouds, and showers bring good news and bad
news. Good, the daily temperature spread will shrink with mild
mornings and less hot afternoons. Bad, dewpoints in the 50s will
keep the afternoons feeling muggy. More good, fire concerns are

.LONG TERM...(Thursday through Tuesday)
Issued at 230 PM MDT Tue Jul 19 2016

Through Friday, the moist SW flow continues. Both the more moist
NAM and the drier GFS keep precipitable water values over one
inch. No significant disturbances are resolved for now so a
braod brush monsoonal surge forecast continues. The southern and
eastern portion of the forecast area looks to be favored for

By Saturday, the Pacific NW upper Low ejects through the northern
Rockies. This turns the upper flow from SW to a drier west. The
subtropical High also expands across the southern tier of states.
All of this brings a strong drying and warming trend to the
forecast area that continues into at least next Tuesday.


.AVIATION...(For the 00Z TAFS through 00Z Wednesday afternoon)
Issued at 230 PM MDT Tue Jul 19 2016

Moist monsoonal flow will continue to dictate shower and
thunderstorm development over eastern Utah and western Colorado
over the next 24 hours. Storm coverage is expected to diminish
after sunset. However it is likely that some activity will
survive well into the early morning hours especially in the
vicinity of KDRO KTEX. Outflow from passing storms/showers will
also create gusty localized outflow winds.

VFR conditions will prevail but TSRA/+TSRA will temporarily
produce IFR VIS and possibly MVFR CIGS. Storm coverage will
increase again Wednesday after 18z with the best coverage
expected along and south of a line from KCNY northeast to KSBS.


.GJT Watches/Warnings/Advisories...


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