Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Amarillo Texas
611 am CDT Wednesday Aug 20 2014
southerly winds will get gusty at all taf sites by middle morning.
Thunderstorm chances look best at dht later this afternoon...but
believe that the coverage will be pretty isolated...so the chances of
one going right over the taf site looks slim...so will not mention at
this time. Winds will slow to 10 to 15 knots by sunset. Skies will
remain VFR outside of thunderstorms.
Previous discussion... /issued 405 am CDT Wednesday Aug 20 2014/
persistent low thunderstorm chances and near to above average
temperatures highlight this forecast.
The upper ridge that was centered over the area yesterday was
translating eastward early this morning...downstream of upper
troughing over the western Continental U.S.. water vapor imagery showed monsoon
moisture starting to advect back into the western panhandles aboard
the developing southwest flow aloft. A Lee surface trough draped
south across eastern Colorado and nm was maintaining southerly
breezes across the panhandles...which were helping to hold
temperatures in the upper 60s to middle 70s as of 4 am.
The upper ridge will continue to shift off to our east
today...leaving the region under a southwest flow aloft between the
ridge and western trough. This flow will continue to draw some
monsoon moisture back into the panhandles...supporting chances for
some isolated to scattered showers and thunderstorms across the
western and central panhandles this afternoon into tonight. The
southwesterly steering flow will also be favorable to bring in some
convection off the nm higher terrain...as well as any storms that
may develop along the Lee trough axis. Brief strong gusty winds will
be the main concern with any stronger storms due to a dry sub-cloud
layer beneath cloud bases between 600-700mb. Otherwise it will be a
warm...breezy day as south winds pick up to 15-25 miles per hour east of the Lee
trough...helping to push temperatures into the 90s area wide.
The upper ridge will remain displaced to our east through the
weekend...with mean troughing persisting across the west. Resultant
flow aloft will keep some monsoon moisture over the area...leading to
daily at least low thunderstorm chances across portions of the
area through the weekend. The Cross-Mountain flow will also
maintain a decent Lee surface trough...which will support breezy
southerly winds the next several days and may also serve as a trigger
for diurnal convection. The embedded closed upper low currently over
Southern California is expected to open up and weaken as it ejects
east/northeast...but may provide a little better forcing for precipitation
toward Saturday as it moves across the area.
It still looks like a weak cold front will try to push into the area
Sunday night/Monday as the upper trough over the Pacific northwest advances
east across the northern rockies and plains...but how far south the
front will actually get is still up for debate. However it does look
like a better frontal push may come at the end of the forecast period
/next Wednesday/ as the upper trough may get its final push eastward.
Have extended precipitation chances into early next week and nudged
temperatures down a bit given the possible frontal intrusions along
with some lingering monsoonal moisture and glancing upper dynamics.
southerly winds will increase into the 15 to 25 miles per hour range the next
few days as a Lee surface trough maintains a tightened pressure
gradient across the area. Despite the breezy conditions...no elevated
or critical fire weather conditions are expected due to forecast
minimum relative humidities remaining above 20 percent and