Area forecast discussion 
National Weather Service Tucson Arizona 
225 am MST Wednesday may 22 2013 


Synopsis...warmer today as a weak ridge pushes out of the state. An 
upper level low in the Pacific northwest will deepen along the 
entire West Coast and linger over the region well into next week. 
This will result in a prolonged period of dry southwest flow across 
southern Arizona with above average afternoon temperatures and gusty 
winds at times. 


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Discussion...short wave ridge that was over the area on Tuesday 
will be east of the area today. Even with the ridge to our east 
there still will be an increase in low level thickness values 
resulting in warmer temperatures and possibly the first triple digit 
high of 2013 being recorded in Tucson. Check the climate section 
below for more information on this. Otherwise breezy to localized windy 
today. 


Thursday...southwest flow aloft over the state with broad upper low 
to our northwest. Breezy to locally windy across the area with highs a few 
degrees cooler than Wednesday. 


Friday through the Memorial Holiday weekend....upper level trofiness 
remains over the western states with southwest flow aloft continuing 
across the state. Daily highs remaining a few degrees above normal. 


Tuesday...dry upper level trough through the state resulting in cooler 
temperatures with GFS cooler than ec. At this time...leaned toward 
the warmer ec. 


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Aviation...sct-bkn clouds at or above 20k feet becmg few-scattered after 22/17z. 
Surface wind less than 10 kts through 22/15z then southerly/southwesterly at 12-17 kts 
with gusts around 25 kts through 23/03z. Surface wind generally less 
than 10 kts again after 23/03z. Aviation discussion not updated for 
taf amendments. 


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Fire weather...high pressure aloft will continue across the Desert 
Southwest through much of the the week...resulting in dry conditions 
and warm temperatures with above normal readings. A trough will form 
along the West Coast late this week into the weekend for some 
cooling and gusty winds at times. Critical fire weather thresholds 
may be exceeded this afternoon and again Thursday afternoon in the 
mountains of northern Greenlee County (the alpine district) where a 
red flag warning remains in effect from noon until 8 PM MST. 


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Climate...after making the first run at the first triple digit high 
of 2013 for Tucson a week ago...we have been targeting today since 
late last week as the next best shot. Based on the latest model 
data...today looks like a solid 99...with about a 10% chance that 
tia will hit 100. If 100 occurs...it will probably be in the 215 PM 
to 345 PM time frame. On a historical note...the first 100 degree of 
high of the year has occurred on may 22nd only once...in 1926. 


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Twc watches/warnings/advisories... 
red flag warning today and Thursday from 12 noon until 8 PM for 
northern fire weather zone 146 including the alpine district. 


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