Area forecast discussion 
National Weather Service Tucson Arizona 
830 PM MST Tuesday Sep 2 2014 


Synopsis...the chance of thunderstorms will increase starting 
Wednesday and especially by this weekend as deeper moisture moves 
into Southeast Arizona. Areas of heavy rain are possible over the 
weekend into early next week. As the chance of rain increases...our 
recent string of hot temperatures will be broken with daytime highs 
falling below average over the weekend. 


&& 


Discussion...00z sounding around 3/4 of an inch with the start of 
more promising temperature profile trends in middle levels (cooling 
between 500 mb and h7) as high pressure starts to reconsolidate east of 
the area. Shallow outflow from strong complex through eastern Sonora 
just south of the border will combine with Gulf surge activity 
overnight to begin the moisture push tonight. Shallow at first as 
surface dew points respond over the next 12 hours...but gaining 
depth with time as some flavor of surge will be sustained over the 
next 5-6 days or so with several reinforcing waves. 


Isolated convection Wednesday with an emphasis on international 
border areas (especially Santa Cruz county)...then ramping up in 
coverage and intensity Thursday and especially Friday as the initial 
surge is reinforced by right front quadrant influences from Norbert 
down near southern Baja California. 


By Saturday and Sunday this is further reinforced by arrival of 
moisture pushed ahead of the remains of Dolly (from the Gulf of 
mexico) around the southern periphery of the strengthening high east 
of our area. The atmosphere will be very wet at that point and 
should have a reasonably robust southerly wind profile for organized 
convection. Expect an elevated chance of near severe organized 
outflow winds Friday and Saturday. Friday could be a prime day for 
convective blowing dust. Saturday and especially Sunday through 
Monday or Tuesday will see a marked enhancement to chances of heavy 
rain and localized flash flood concerns. 


After that...we may see the tail end of our first early season 
trough knock the deep moisture back south and southeast by Wednesday 
or Thursday. 


Summary main concerns for each day: 
Thursday-Fri: potential severe/blowing dust 
Sat: potential severe/heavy rain 
sun-Mon/Tue: potential heavy rain 


&& 


Aviation...valid through 04/04z. 
Mostly clear overnight...then increasing moisture will bring a few 
thunderstorms back to Southeast Arizona Wednesday afternoon. 
Isolated -shra/-tsra mainly south/southeast of ktus Wednesday 
afternoon and early evening. Surface wind generally less than 10 kts 
through Wednesday afternoon...expect strong and gusty near any 
-shra/-tsra development. Aviation discussion not updated for taf 
amendments. 


&& 


Fire weather...daytime highs still well above average into 
Thursday...however moisture will start to increase from the south 
tonight. Isolated thunderstorms developing Wednesday 
afternoon...especially south and southeast of Tucson. Isolated to 
scattered showers and thunderstorms will occur areawide Thursday and 
Friday. Numerous showers and thunderstorms then expected over the 
upcoming weekend into early next week as deeper moisture moves back 
into the region. The potential for heavy rainfall exists this 
weekend through early next week. 20-foot winds will generally be 
light and terrain driven into Wednesday. Thereafter...gusty outflows 
associated with the thunderstorms will occur Thursday through the 
weekend. 


&& 


Twc watches/warnings/advisories...none. 


&& 


$$ 


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