Area forecast discussion 
National Weather Service Phoenix Arizona 
400 am MST Tuesday Mar 31 2015 

Update...aviation and fire weather discussions. 


dry weak troughing will slowly continue to work across the area with 
periods of passing high clouds. Another dry weather system will move 
into the region from the Great Basin late Wednesday through 
Friday...ushering in cooler temperatures and increasing winds. Dry 
conditions will remain through the weekend with continued above 
normal temperatures with daytime highs in the upper 80s to low 90s. 


much clearer skies noted on water vapor/infrared imagery this early am 
across southeast California and south-central Arizona. Only some pockets of cumulus 
still observed over eastern Gila County with more widespread cumulus and 
cirrus fields across Southeast Arizona this am. Any lingering radar 
returns on kemx (tucson weather radar) are south of the border closer to 
the pvu and dynamics of the cut-off low now over the Baja California spur. Even 
a few strikes of lightning have been noted along the Sonora/Chihuahua 
border from more organized shower/thundershower activity embedded in 
The Heart of tropical moisture plume and satellite derived upper jet 
maxima. The cut-off will continue a slow track eastward over northern 
Mexico through the day...translating additional shower/thunderstorm 
activity further to the east across nm/West Texas by the afternoon. 

Additional weak shortwave tracking along the northern Arizona 
border will move through with little impact to our forecast for some periods of passing high level clouds possibly 
setting up another gorgeous southwest sunset later today. 
Temperatures will be a few degrees cooler than the past few 
afternoons...but still flirt with records at least in Phoenix today. 
Record high for this day is 94f (2012) and that is what we are 
currently forecasting. Yuma-el centro-Blythe can look for middle 90s 
again as well...while the higher terrain locales of Globe and jtnp 
can look for daytime highs in the 80s. 

Operational and ensemble height forecasts are in the good agreement 
through the middle of the weekend...advertising mostly zonal flow 
across the southwest states. Passing Great Basin shortwave from the 
northern storm track will clip northern Arizona Thursday bringing in some 
drier air and mild cold air advection into the region...particularly along and 
through the Colorado River valley. In addition...ul jet streak moving off 
the eastern Pacific as part of the southern storm track will help 
enhance winds along the base of the trough...resulting in breezy to 
locally windy conditions Thursday. Main impacts from this system for 
Thursday will be windy conditions...cooler temperatures and crashing 
dewpoint readings. The combination of strong winds and low rhs (with 
many of the western fire districts in our forecast area in the single 
digits) may lead to critical fire weather conditions during the day 
Thursday. Current wind speed forecasts do not support widespread 
areal concerns...but conditions may be realized in localized pockets. 
Will highlight the fire weather concerns with a headline in the fire 
weather forecast product (fwfpsr) at this time. 

After the late week shortwave clears the region...broad trough 
heights/southwesterly flow remain over much of the western Continental U.S. 
Through early next week. Operational GFS/European model (ecmwf) solutions advertise 
a large shortwave moving off the Pacific late Sunday/early 
Monday...however their ensemble (gefs/naefs/ecens) counterparts do 
little to inspire confidence in the evolution of that system. 
Broadbrush forecast will hold through the weekend and into early 
next week of continued dry conditions and slightly above-climatology 



Record highs this week... 

City March 31 
-------- -------- 
Phoenix 94 in 2012 
Yuma 100 in 2011 


Aviation... south-central Arizona including kphx...kiwa...and 
ksdl...and southeast California and southwest Arizona including kipl 
and kblh... 

Weak Pacific disturbance is forecast to move across northern Arizona late 
today resulting in gusty afternoon/evening west winds. Through 17z 
Tuesday...mostly clear. Light wind under 8 knots. From 17z Tuesday to 02z 
Wednesday...increasing west wind 12 to 15 knots with gusts to 22 knots. 
Occasional high clouds. 

Aviation discussion not updated for amended tafs. 


Fire weather... 

..gusty northwest winds and very low humidity area-wide Thursday 
afternoon for marginal fire weather conditions... 

Thursday through Monday... a series of weather disturbances will 
move across the western states mainly north of Arizona for enhanced 
afternoon breezes each day. However one stronger disturbance will 
move farther south across northern Arizona Thursday generating gusty 
north to northwest winds 15 to 25 miles per hour with gusts to 30 miles per hour. A 
significantly drier airmass from the north will also sweep across 
the region. Marginal fire weather conditions are expected Thursday. 
Otherwise...breezy conditions are forecast each afternoon with 
minimum relative humidities in the 5 to 10 percent range. Overnight 
recovery should be fair...except for the breezy/windy period 
Thursday night. Afternoon temperatures will remain 8 to 10 degrees 
above normal. 


Psr watches/warnings/advisories... 


Visit US on facebook...twitter...and at weather.Gov/Phoenix 

fire weather...vasquez 

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