Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 301742
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1242 PM CDT Wed Jul 30 2014

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 305 AM CDT WED JUL 30 2014

Early Wednesday morning, a strong short wave trough was gradually
moving east across the Oklahoma panhandle. There is ample moisture
associated with this system. However, persistent dry northerly flow
has been in place across the northern Plains and into northeast
Kansas. This drier and cooler air has kept the forecast area
generally dry, but has also put a temperature gradient in place with
a band of persistent frontogenesis hovering across the region since
Tuesday morning. This frontogenesis intensified a bit this morning
amidst a moist mid-level airmass with very weak instability,
resulting in a band of showers even with embedded pockets of
moderate rain. The higher resolution model guidance has been
performing well in handling these features over the past 30 hours
and solutions through today seem quite reasonable and have leaned on
those solutions heavily. That said, expect this band of showers to
persist and slowly shift south and east this morning, with a
weakening trend after around 15Z. While the frontogenesis will be
weakening at this time, the short wave will get a bit closer to the
area so could see scattered showers persist into the afternoon,
although likely with less coverage than early this morning. Also,
the precip potential area will continue to shift south through the
day, likely focused south of I-35 by early afternoon. A "rain-out"
should not be expected for any part of the forecast area, but
typically less than 2 hours of total shower activity for any given
point. Daytime warming will be limited by cloud cover, especially in
east central KS, and highs will range from the upper 70s to lower
80s. Expect gradually clearing skies overnight along with light
winds. Lows should drop into the upper 50s to lower 60s for the
entire area, with the coolest temps north.

.LONG TERM...(Thursday through Tuesday)
Issued at 305 AM CDT WED JUL 30 2014

Surface ridge axis settles over northern MO by Thursday as the upper
trough continues to rotate over the northern Great Lakes region.
Weak embedded waves translate through the northwest flow across the
Midwest Thursday evening through Saturday. Guidance is still varying
between runs on small amounts of QPF versus completely dry during
this period. The latest run of the NAM is too aggressive, possibly
owning to convective feedback while the GFS/ECMWF/GEM are further
east with the optimal mid level lift. Sounding profiles also
suggest copious amounts of dry air to overcome so will continue
with a dry forecast through Monday evening.

The next, more poignant upper trough and cold front dips southeast
across the western high plains beginning Tuesday. Decided to trim
back precip chances as the latest GFS ensembles have slowed on
timing of the wave until Wednesday. The ECMWF is still on track to
impact north central areas on Tuesday and will therefore leave a
slight chance mention.

After high pressure brings light and variable winds Thursday through
Saturday, surface trough begins to build over the northern plains,
returning the southerly flow and warming temperatures. After highs
gradually rising into the middle 80s through Sunday, 90s return
Sunday through Tuesday.

&&

.AVIATION...(For the 18Z TAFs through 18Z Thursday Afternoon)
Issued at 1230 PM CDT WED JUL 30 2014

Vfr conditions will continue through the period with sct stratocu around
5 kft until 00z before gradually dissipating. Considered adding some
mvfr vsbys in fog at KMHK towards 12z/31...but with some high level
clouds possible decided to hold off for now...but the potential will
need to be reevaluated with the 00Z TAF issuance. Other light northeast
winds becoming light and variable or clam aft 00z will be the rule.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Barjenbruch
LONG TERM...Bowen
AVIATION...63





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