Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Flagstaff Arizona
316 PM MST Friday Sep 4 2015
Synopsis...scattered showers and thunderstorms will continue over
the next several days...with the best chances of storms over the
eastern half of the state. Drier conditions may return to northern
Arizona early next week.
Discussion...scattered thunderstorms will continue to develop
over northern Arizona this afternoon. Storm Prediction Center mesoscale analysis
indicates middle-level lapse rates between 5.5-6.5 c/km. The nearly
moist adiabatic middle-level lapse rates are keeping convection from
growing upscale this afternoon...minimizing storm intensity. This
will likely continue into the evening hours...with the main hazard
from these storms being lightning.
Saturday through Tuesday...a trough just offshore the western
Continental U.S. Is prognosticated to pivot east into California. This will push
deep monsoonal moisture east of the region...with drier air
filtering into western and central Arizona. Still kept slight
chance probability of precipitation in for the potential of diurnally driven
Wednesday through Friday...there is a lot of uncertainty regarding
the forecast during this period. Currently there is a tropical
disturbance 575 miles south of Manzanillo, Mexico. Both the European model (ecmwf)
and GFS forecast this disturbance to develop into a tropical cyclone
next week. Although the center of circulation is prognosticated to
remain well offshore the eastern Pacific...deep tropical moisture
could be advected over northern Arizona leading to an increase in
covective activity during this period. Stay tuned for updates!
Aviation...for the 00z package...scattered rain showers/thunderstorms and rain will
continue across northern Arizona through sunset. Greatest aviation
concerns will be local IFR conditions in stronger storms...along
with isolated hail. Breezy southerly winds at 10-20 kts gusting
near 30 kts across western Arizona.
Aviation discussion not updated for taf amendments.
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