Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Tucson Arizona
940 am MST Thursday Nov 27 2014
Synopsis...dry conditions with warm daytime highs into early next
week. A Pacific storm system may then bring a chance of valley rain
and mountain snow showers around the middle of next week.
Discussion...IR/visible satellite imagery and surface observations
indicate clear skies across Southeast Arizona at this time. A somewhat tight
surface pressure gradient has led to an Ely/southeasterly near-surface flow
regime. Surface winds valid 16z were generally Ely/southeasterly at 5-15 miles per hour
and a gust to 22 miles per hour was observed at ktus. Meanwhile...dewpoints at
lower elevations valid 16z were in the upper teens to lower 20s f...
and these temperatures were about 15-20 degrees f higher versus 24 hours ago.
Surface temperatures valid 16z were 5-20 degrees f warmer versus this time
Wednesday. 27/12z ktwc sounding total precipitation water value was 0.28 inch...
still representative of a very dry regime. 27/12z upper air plots
depicted a 589 dm high centered west of the Baja California California spur
vicinity 26n/121w...and ridge axis extended northeastward into the northern
rockies. Light northerly/northeasterly flow above 700 mb prevailed over Southeast Arizona.
Expect sunny skies today...locally gusty Ely/southeasterly winds...and high
temperatures that will average about 5-10 degrees f above normal. There are no
updates planned at this time. Please refer to the additional
sections for further detail.
Aviation...valid through 28/18z.
A high pressure ridge aloft will maintain VFR conditions through Friday
morning. Expect clear skies today then a few to perhaps scattered
clouds above 20k feet above ground level tonight into Friday morning. Surface wind
into Friday morning will be Ely/southeasterly 5-15 kts with occasional gusts
to around 20 kts. Aviation discussion not updated for taf amendments.
Fire weather...expect dry conditions with well above average
daytime temperatures through Monday. A Pacific storm system may then
bring a chance of valley rain and mountain snow showers around the
middle of next week. Locally gusty east winds today...otherwise
normal diurnal wind trends into early next week.
Previous discussion...much weaker middle and upper level flow as the ridge
axis aloft phases in from the west and loses amplitude. We'll manage
to warm up quickly with a moderate low level easterly gradient
enhancement...generally downslope for most of our County Warning Area. Daytime highs
around 8 to 12 degrees above climatology the next several days...through
at least Sunday.
High energy pattern in the eastern Pacific with significant
questions about the strength of the southern branch split that will
develop. A fairly wet 7 day period is a good call if you live in
central to northern California and the Pacific northwest...however
southern latitudes such as ours may be at the mercy of a full
cut-off low. Timing and trajectories are all over the place within
individual model ensemble trends as well as trying to arrive at any
consensus and trends comparing operational resolutions. There are
many times when we can do a solid job forecasting 6-10 days even
with Pacific storm systems at our latitude...but this is not one of
them. Overall the trends are getting drier and drier this far south
and east...especially with the favored European model (ecmwf).
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fire weather/previous discussion...Meyer