Area forecast discussion 
National Weather Service Phoenix Arizona 
329 PM MST Thursday Feb 11 2016 


Synopsis... 
strong high pressure and unseasonably warm temperatures will remain 
dominant over the southwestern United States into the middle of next 
week. This will result in a prolonged period of sunny skies...much 
above normal temperatures...relatively light winds...and low 
humidity values. 


&& 


Discussion... 
latest streamline analysis places the center of the 850-300 mb 
anticyclone near Lake Havasu City and it will continue sliding eastward 
into central Arizona tonight. Morning radiosonde observations from both ktwc and kfgz were 
quite warm above the low-level inversion with 700 mb temperatures at 
record values for both sites. This has translated into sunny skies 
with well above normal temperatures observed across the Desert 
Southwest this afternoon. 


Record high temperature of 83 degrees was eclipsed earlier this 
afternoon. Operational models remain quite consistent and clustered. 
Consequently...little change was made to the forecast. Clear skies 
expected overnight with above normal min temperatures persisting. 


&& 


Previous discussion... 
record or near record temperatures and dry conditions will continue 
into next week as an anomalously strong high pressure ridge remains 
the dominant weather feature across much of the western United 
States. Naefs ensemble heights and temperatures over the southwestern 
United States are easily above the 90th percentile and in fact near 
records compared to climatology for today into Friday. Little change 
in sensible weather is forecast for both days compared to the last 
couple days as highs will again peak out in the middle to upper 80s 
in many Lower Desert spots. 


Model deterministic output and ensemble guidance show the strong 
ridge breaking down slightly on Friday into this weekend...first 
from a Pacific trough on Friday and then as a weak shortwave trough 
dives southeastward through the Desert Southwest this weekend. 
Heights aloft will drop a good amount...though still above 
climatology...but this will have little effect on temperatures below 
700mb and only drop Saturday and Sunday highs down a couple degrees. 
We should at least see a bit of high clouds Saturday into early 
Sunday...but they likely won't bring any relief from the very warm 
temperatures. 


Another anomalously strong ridge will build across the eastern 
Pacific this weekend and move over the western United States for 
early next week. Again we should see near or record heights and 
temperatures over the Desert Southwest...likely for next Tuesday and 
Wednesday. Highs by Wednesday could climb slightly above what we are 
currently seeing. Some guidance even has the Phoenix area hitting 90 
degrees which would break the record for the first 90 degree day of 
the year by around a week. For now will keep highs slightly shy of 90 
with the warmest values falling on Wednesday. We should get some 
minor relief later next week as a strong trough is shown to push 
across the Great Basin or even a bit further south into northern 
Arizona. Thinking is this will drop our temperatures well out of 
record territory...but the lower deserts should likely still see 80 
degrees or just above. 


&& 


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


The latest satellite imagery shows clear skies across the region 
with skies expected to remain clear to mostly clear throughout the 
period. The winds in all areas will be light to occasionally calm 
and/or light and variable and follow familiar diurnal trends. 
Otherwise expect good to excellent visibilities throughout the 
region. 


Aviation discussion not updated for amended tafs. 


&& 


Fire weather... 
Saturday through Wednesday...an unseasonably strong high pressure 
ridge will remain in place over the western states into early next 
week. This will bring mostly sunny skies and a persistent period of 
well above normals high temperatures...with daytime highs at many 
lower elevation and desert sites warming into the upper 80s to near 
90 degrees. Minimum humidity levels will hover in the teens across 
all districts. Light winds are expected during this period...except 
for increased northerly breezes along the lower Colorado River 
valley Sunday and Monday. 


&& 


Climate... 


Phoenix | Yuma 
forecast | record /year/ | forecast | record /year/ 


Thursday Feb 11 86 | 83 /1951/ | 87 | 86 /1971/ 
Friday Feb 12 88 | 84 /1988/ | 87 | 87 /1957/ 
Sat Feb 13 87 | 88 /1957/ | 86 | 93 /1957/ 
sun Feb 14 86 | 85 /2014/ | 85 | 94 /1957/ 
Monday Feb 15 87 | 86 /2014/ | 85 | 89 /2014/ 
Tuesday Feb 16 88 | 84 /2014/ | 86 | 88 /1981/ 
Wednesday Feb 17 89 | 88 /2014/ | 86 | 88 /2014/ 


&& 


Spotter information statement... 
spotters are encouraged to report based on Standard operating 
procedures. 


&& 


Psr watches/warnings/advisories... 
Arizona...none. 
California...none. 
&& 


$$ 


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


Discussion...Hirsch 
previous discussion...Kuhlman 
aviation...Sawtelle 
fire weather...Meyers 






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