Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 201025
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
325 AM MST WED JUL 20 2016

.SYNOPSIS...Today will see another round of isolated to scattered
afternoon and evening showers and thunderstorms. A decrease in
coverage of showers and thunderstorms will then prevail Thursday into
this weekend. Expect hotter daytime temperatures Thursday through
Saturday followed by a minor moderation in temperatures early next
week.

&&

.DISCUSSION...After an active afternoon and evening across the area
on Tuesday, partly to mostly cloudy conditions prevailed across the
area at 3 am. The bulk of any shower activity early this morning
will be up around Phoenix. PW values across the area this morning
were in the 1.25" to 1.60" range will little change expected today.
Areal coverage of storms today should be a bit less than yesterday
with 00z WRF runs of the NAM/GFS depicting better chances this
evening across the area. The upper level feature that was over
northern Chihuahua MX yesterday is now over eastern AZ. Looking at
water vapor this morning, there may be a upper level disturbance
over Sonora MX which would lift north toward the area an provided
added dynamics later today. Made some slight adjustments to the PoP
grids but pretty much kept scattered storms in the forecast for this
afternoon and evening. Could be overdone in the valleys this
afternoon. Highs today will be near what was observed yesterday.

Sub-tropical upper ridge to expand west across the desert southwest
starting Thursday and continuing into the upcoming weekend. The will
bring hotter daytime temperatures to the area with near record highs
possible starting Thursday and continuing into the weekend. See
climate section below. Expect a slow drying trend Thu thru Sat
resulting in a gradual decrease in the areal coverage of afternoon
and evening storms, but not a complete shutdown like earlier this
month. Will have to keep an eye for any inverted trofs that may pass
by to our south that could enhance storm activity. Timing of these
features usually tough. Will be interesting to see if the inverted
trof that is currently moving through the Gulf of Mexico will have
any impact here, if it holds together, either Friday or Saturday.

Early next week could see a renewed influx of tropical moisture into
northern Mexico that may eventually end up across our area.

&&

.AVIATION...VALID THRU 21/12Z.
Few-sct clouds at 7-11k ft agl and sct-bkn clouds AOA 15k ft agl
thru 20/19z. Aft 20/19z, sct-bkn clouds at 6-9k ft agl and bkn-ovc
clouds at 10-15k ft agl. Expect isolated to scattered showers and
thunderstorms to develop during the early afternoon, persisting
through the mid evening hours tonight. Brief wind gusts to 45 kts
and MVFR conditions will occur with the stronger TSRA. Outside of
thunderstorm outflows, sfc wind will generally be less than 12 kts
thru the forecast cycle. 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 through 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
on Thursday then most of the area will be at or near record highs
Friday and Saturday.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...None.

&&

$$

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