Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Flagstaff Arizona
920 am MST Tuesday Oct 13 2015
Synopsis...high pressure over northern Arizona will bring warm
and dry weather through Wednesday. High temperatures will be 10 to
15 degrees above normal. On Thursday...a low pressure system will
begin to affect northern Arizona...leading to cooling
temperatures...increasing winds and increasing chances for
precipitation through the weekend.
Discussion...current forecast is in good shape...no updates needed.
Previous discussion /300 am MST/...for today and Wednesday...high
pressure will remain in place across northern Arizona leading to
another day of well above normal temperatures, light winds, dry
weather and mostly clear skies. This morning's surface observations
reveal that northern Arizona continues to dry as dew points have
dropped considerably since yesterday morning. Observed and forecast
soundings reveal the atmosphere remains too dry and stable for
precipitation - or for low cloud development for that matter. In
addition, with low pressure now well to the west of the state, very
little passing high cloud is expected. High temperatures today are
forecast to be around 10 to 15 degrees above normal at most places.
In fact, high temperatures will approach record values at several
locations across northern Arizona. Here is a list of a few sites
forecast to be within 3 degrees of their record value.
Forecast hi record hi
Flagstaff anomolous propagation 77f 79f
Prescott anomolous propagation 85f 88f
Page anomolous propagation 84f 82f
Window Rock anomolous propagation 82f 80f
Payson 85f 88f
Expect another abnormally warm day on Wednesday, with high
temperatures within a degree of two of tuesday's values.
Meanwhile, the low pressure system that brought rain to northern
Arizona early last week is forecast to move northward from its
current location off the West Coast of Baja California California to off the
coast of Southern California by Wednesday.
Thursday through Saturday...the low pressure system off the
Southern California coast is forecast to push eastward affecting
northern Arizona for the second time. Models are in reasonable
agreement with respect to the timing of the precipitation. Expect
increasing chances for showers and thunderstorms from west to
east beginning on Thursday, with the most widespread precipitation
on Friday. This is when the best combination of upper level
forcing and moisture/instability will exist. Good chances for
showers and thunderstorms will continue on Saturday as the upper
level trough axis passes overhead. Daytime temperatures are
forecast to drop to near normal by Friday.
From Sunday Onward...longer term models generally agree that
northern Arizona will be affected by a second low pressure system
on the heels of the first. As a result, the forecast calls for
continued chances for showers through the early part of the next
work week. High temperatures are forecast to remain near normal.
Aviation...for the 18z package...high pressure will continue to
bring VFR conditions and light winds over the next 24 hours.
Aviation discussion not updated for taf amendments.
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