Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 182225

Area Forecast Discussion
National Weather Service Tucson AZ
325 PM MST Wed Oct 18 2017

.SYNOPSIS...Continued above normal temperatures. A fast moving
disturbance will bring isolated showers and thunderstorms Wednesday
night into Thursday, mainly near eastern mountains. Expect some
modest cooling Friday and Saturday, then near record high
temperatures are expected early next week as high pressure aloft
builds over the area.


.DISCUSSION...Our ridge is buckling and dirtying up as the flow
becomes a little more zonal. A bit of moisture around for a few
showers well east of Tucson earlier this afternoon.

An impulse coming in off the Pacific will bring a little more
moisture over the next 24 hours with a few more showers or
thunderstorms Thursday. Orographics will help with best chances
near eastern mountains.

Some respite from the temperatures, as a trough pushes through the
region Friday into Saturday. Breezy southwest to west winds by
Friday afternoon, with cooler air filtering in as a dry
northwesterly flow sets up behind the trough Saturday. Daytime
temperatures will actually approach seasonal normals Saturday
afternoon. Saturday night and Sunday night will by on the chilly
side compared to recent weeks. Some isolated locations in coldest
Cochise County valley locations could touch freezing.

Strong high pressure will build in from the eastern Pacific
through Arizona and California early in the new week. Forecast
height and thickness values support temperatures more like the end
of August or beginning of September, with record values around 12
to 14 degrees above average the first half of next week. Please
see the Climate section below for additional details.


.AVIATION...Valid thru 20/00Z.
FEW-SCT clouds at 8-12k ft AGL and SCT clouds above 20k ft AGL
through a majority of the forecast period. Isolated -SHRA/-TSRA this
afternoon along the eastern periphery of the state, picking up again
on Thursday. SFC wind terrain driven and less than 12 kts through
the forecast period. Aviation discussion not updated for TAF


.FIRE WEATHER...As a weak disturbance moves through the region,
isolated showers and thunderstorms will develop along the eastern
portion of the state through Thursday. Dry conditions then
overspread the area lasting into next week. Normal diurnal wind
trends will continue through Thursday, becoming breezy from the
southwest on Friday. An easterly wind regime then sets up for Sunday
into early next week.


.CLIMATE...Today marks the 178th day of 90 degree temperatures
this year. That ties the record (1989 and 1910), with tomorrow
likely breaking the record. It`s also 132nd day of 95 degree
temperatures, which ties 1988 as 5th most.

After a break over the weekend, record or near record high
temperatures are likely early next week as an unseasonably strong
ridge of high pressure aloft builds over the area. Current
forecast high of 97 for Tucson Intl next Tuesday, if correct,
would be the 2nd latest occurrence of 97 in the calendar on
record. The record latest date is Oct 27 2016. There is a small
chance next Tuesday that the high at Tucson Intl could hit 98,
which, if that happens, would be the latest occurrence of 98 in
the calendar on record, besting the current latest date of Oct 19
in 1921 & 1991.

         Tucson International Airport
             Forecast  Record
Mon Oct 23      95       94
Tue Oct 24      97       96
Wed Oct 25      95       95






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