Weather Service Report

FXUS65 KTWC 200404

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

.SYNOPSIS...High pressure will bring a strong warming trend through 
Thursday. 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 area.


.DISCUSSION...Latest IR/WV imagery shows flat ridging building into 
the region with just a few thin cirroform clouds moving through 
overnight. Temperatures are quickly cooling off this evening with 
low temperatures Tuesday morning forecast to be about 5 degrees 
below normal. Otherwise, warming will continue on Tuesday as ridging 
continues to build in with rising heights and thicknesses. This will 
result in highs about 7 to 10 degrees warmer than today. Current 
forecast in good shape, no updates this evening. See previous 
forecast discussion below for additional information.  


.AVIATION...Valid through 21/06Z.
Generally clear skies through the forecast period with SCT clouds 
above 20k ft AGL possible. SFC winds generally variable 10 kts or 
less thru the period, though they will tend to be more focused 
from a WLY-NWLY direction during the afternoon. 

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 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 90 
degrees for Thursday, March 22 would tie 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.


.PREV 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.






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