Area Forecast Discussion
Issued by NWS Tucson, AZ

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144
FXUS65 KTWC 191654
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
954 AM MST Thu Oct 19 2017

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

&&

.DISCUSSION...No surprises this morning with a weak impulse
pushing across the area as the ridge axis shifts eastward.
Precipitable water pushing back into the .75 to 1 inch range, but
the bulk of that moisture is above 650hPa. Lower levels still
dryish with surface dew points in the 30s south to middle 40s
north. Still expecting most shower activity to be north and
northeast of Tucson, with an emphasis on Pinal, Graham and
Greenlee counties this afternoon. A few lighting strikes mixed in
there, but actual precip amounts will be modest. Please see the
previous discussion for additional details beyond today, as we see
a break in the above normal temperatures over the weekend only to
see them charge back up early next week.

&&

.AVIATION...Valid thru 20/18Z.
FEW-SCT clouds at 8-12k ft AGL, locally BKN. Isolated
-SHRA/-TSRA mainly northeast/east of KTUS thru 20/05Z. SFC wind
less than 10 kts thru 19/18Z, then SWLY/WLY SFC wind at 8-12 kts
with gusts to 18 kts between 19/18Z and 20/02Z. Aft 20/02Z, SFC
wind less than 10 kts. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...A weak disturbance moving across the region will
result in isolated showers and thunderstorms over eastern portions
of the forecast area through this evening. Dry conditions are then
expected starting on Friday and continuing through at least the
middle of next week. Southwest winds will be up just a bit today and
then winds will be breezy from the southwest to west on Friday into
Saturday. An easterly wind regime sets up on Sunday into early next
week.

&&

.PREV DISCUSSION...Weak upper level trof over western AZ this
morning will continue to move east across the state today. Best
dynamics with this feature will be across northern/central Arizona
with best chances for showers, possibly a t-storm, north and
northeast of Tucson. Slightly cooler today versus Wednesday but
still running well above normal. Another upper level trof passing
by to our north on Friday will continue the cooling trend into
Saturday where highs will be at or slightly below normal. Breezy
conditions also on Friday. Enjoy the cool down as it will heat up
with record to near record highs early next week. See climate
section below for additional details.

&&

.CLIMATE...Record setting day ahead for Tucson with today being
the 179th day of 90+ degree high temperatures for 2017. This would
break the record of 178 days which occurred in 1910 and 1989.

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 96 for Tucson Intl next Tuesday, but there`s a chance at
97. That would be the 2nd latest occurrence of 97 in the calendar
on record. The record latest date is Oct 27 2016. There is also 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      96       96
Wed Oct 25      94       95

&&

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

&&

$$

Meyer

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