Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 192201

Area Forecast Discussion
National Weather Service Tucson AZ
301 PM MST Mon Mar 19 2018

.SYNOPSIS...High pressure will bring a strong warming trend the
first half of the week. Another system will brush by mainly north of
the area later in the week for a few degrees of cooling and gusty
winds, with the best chance of showers remaining north of the


.DISCUSSION...As high pressure builds in from the west this
afternoon, the expected warming trend has arrived with
temperatures up 4 to 7 degrees compared to yesterday. Rather dry
as well, with precipitable water below 1/4 of an inch on GOES
total precipitable water estimates, and surface dew points
cratering in the single digits and teens this afternoon (down 15
to 25 degrees over the past 24 hours).

Strong warming will continue through mid week; by Wednesday
temperatures will be up 20-25 degrees compared to yesterday. With
the current pattern the ridge axis will have shifted just east of
the area Thursday, but thicknesses still support temperatures even
higher than Wednesday with valley locations typically slower to
respond this time of year. At this point we have a better than 65
percent chance of the first 90 of the year at Tucson International

Some interesting developments in the eastern Pacific as a strong
low off the northern California coast is drawn northward into
higher latitude flow, merging with a system digging down the
Canadian coast over the next 72 hours. Unfortunately only a weak
southern split is supported with as this system pushes into the
region late in the week. That adds up to 10-15 degrees of cooling
with gusty winds and limited precip chances.


.AVIATION...Valid through 21/00Z.
SCT cloud layers above 15k ft AGL. SFC winds this morning
variable less than 10 kts, becoming WLY/NWLY 8-15 kts this
afternoon, diminishing to less than 10 kts this evening.

Aviation discussion not updated for TAF amendments.


.FIRE WEATHER...Dry with a warming trend through Thursday. A Pacific
storm system will bring a slight chance of showers mainly north of
Tucson Thursday night into Friday, as well as cooler temperatures on
Friday. Highs next weekend will be at or slightly above normal. 20-
foot winds will mainly be less than 15 mph today into Wednesday.
Some gusty southwest afternoon winds Thursday into Saturday.


.CLIMATE...A strong ridge of high pressure aloft by mid-week will
bring record or near record highs on Thursday for portions of
southeast Arizona. Not everyone will be near record highs. However,
the Tucson International Airport forecast high temperature of 89
degrees for Thursday, March 22, is within one degree of the record
high of 90 degrees set in 1990. The historical average first 90
degree date of the year in Tucson is April 9. The average date since
1980 has been April 1 while in the 21st century the average first 90
degree occurrence has been March 25.






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