Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 172211

Area Forecast Discussion
National Weather Service Tucson AZ
311 PM MST Tue Oct 17 2017

.SYNOPSIS...Continued above normal temperatures. Variable
cloudiness with a few light showers possible late this afternoon
and evening across southern Cochise county. A fast moving
disturbance will bring isolated showers and thunderstorms
Wednesday night into Thursday, mainly near eastern mountains.
Expect some minor cooling Friday and Saturday, then near record
high temperatures are possible early next week as high pressure
aloft builds over the area.


.DISCUSSION...High pressure over northwest Mexico through our
area and southern California will break down into a zonal flow
over the next couple of days, but we`ll continue to see
temperatures around 10 degrees above average over the next few
days. Our portion of the ridge is dirtying up as a weakness in the
flow brings a modest moisture increase from the west at mid
levels, pushing our precipitable water up past .9 inches. We`ve
also seen a southeasterly surface flow bring in 40+ dew points (up
several degrees over the past 24 hours). Some virga as the cloud
cover thickens a bit today, with a few light showers possible near
the mountains mainly southeast of Tucson.

A weak impulse coming in off the Pacific will bring another chance
of showers late Wednesday into Thursday, primarily east of Tucson
accented by terrain influences. A through western states will
bring several degrees of cooling and breezy conditions late in the
week, but not much else as the main storm track remains north of
our area.

With these few minor exceptions, the main story will continue to
be the unseasonable high temperatures. Near record values are
possible early next week as high pressure rebuilds over the area.


.AVIATION...Valid thru 19/00Z.
FEW-SCT clouds at 8-12k ft AGL and SCT-BKN clouds above 20k ft AGL
thru the forecast period. Slight chance of -TSRA/-SHRA this
afternoon, mainly confined to Cochise County. SFC wind remains
terrain driven and less than 12 kts into Wednesday morning. Aviation
discussion not updated for TAF amendments.


.FIRE WEATHER...A weak disturbance will result in a slight chance of
showers and thunderstorms into Thursday, mainly during the afternoon
and evening hours. Dry conditions then settle in across the region
lasting into the middle of next week. Normal diurnal wind trends
continue through Thursday, becoming breezy Friday afternoon from the
southwest. An easterly wind regime then sets up for Sunday and






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