Area Forecast Discussion
Issued by NWS Tucson, AZ

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991
FXUS65 KTWC 210416
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
916 PM MST WED JUL 20 2016

.SYNOPSIS...A steady decrease in convection will take place Thursday
into the weekend as the air mass over the region dries out. As a
result temperatures will climb to roughly 10 degrees warmer than
average Friday and Saturday. Monsoon moisture will then gradually
return Sunday onward for an overall increase in convection and a
slight cooling of afternoon temperatures.

&&

.DISCUSSION...A rather quiet afternoon and evening convection
wise compared to yesterday. Still a few lingering showers and
thunderstorms mainly across the northern and western fringes of my
forecast area and all of this activity continues moving generally
north. The inherited POP forecast maintains a slight chance of
showers/storms overnight and this seems reasonable, so will not make
any adjustments at this time.

As of 04Z (9 PM MST), temperatures across the region ranged from the
mid 70s to 90 degs, with the Tucson International Airport reporting
a temp of 90 degs. This afternoon the high at TIA was 101 degs,
which was 2 degs above normal for this date. At any rate, the
current readings seem to be on track with the inherited overnight
low temp forecast, so no changes are planned at this time. However,
will continue to monitor surface observations and will make changes
if needed.

For details beyond tonight, please refer to the previous discussion
below.

&&

.AVIATION...VALID THRU 22/06Z.
Isolated Showers and thunderstorms will continue to either diminish
and/or move north through the remainder of the evening. A small
threat for showers/storms will linger during the overnight and early
morning hours. Expect isolated to scattered mostly afternoon and
early evening showers/storms again Thursday. Once again, heavy
rainfall, gusty winds, and some areas of blowing dust will be the
biggest concerns. The expectation is that storms will begin to wane
in coverage after 22/03Z. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...Moisture in place will lead to the daily cycle of
mainly afternoon and evening isolated to scattered showers and
thunderstorms again Thursday. A drying trend will then lead to
reduced coverage of showers and thunderstorms Friday into this
weekend. Moisture will remain adequate for isolated to scattered
thunderstorms early next week. Outside of gusty thunderstorm
outflows, 20-foot winds will be terrain driven and mostly less than
15 mph.

&&

.CLIMATE...Record high temperatures will be approached at a few spots
Thursday then most of the area will be at or near record highs
Friday and Saturday.

&&

.PREV DISCUSSION...A steady drying trend kicks in Thursday and
especially Friday and Saturday with PW`s dropping to around an inch
(a bit more south and a bit less north) by Friday and Saturday. This
will result in a significant decrease in convection despite a wave
sliding by just to our south on Friday. Still carrying some precip
chances mainly near the international border where the highest
amount of moisture will exist.  Afternoon high temperatures will
climb through this period peaking Friday and Saturday nearly 10
degrees above normal.

Sunday onward the models are suggesting the the upper level ridge
will shift slightly north allowing the easterlies to have a greater
influence on our area with an increase in moisture. This will help
to put us back into the daily rounds of afternoon/evening convection
especially if it ends up more like what the ECMWF is suggesting.
Will also see a decrease in afternoon high temperatures down a bit
closer to average next week.

&&

.TWC Watches/Warnings/Advisories...None.

&&

$$

DISCUSSION...Mollere
PREVIOUS DISCUSSION...Cerniglia
AVIATION/FIRE WEATHER....Cantin

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