Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 212345

Area Forecast Discussion
National Weather Service Topeka KS
645 PM CDT Wed Mar 21 2018

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Thursday)
Issued at 356 PM CDT Wed Mar 21 2018

As of 20Z Wednesday afternoon the stagnant mid-level flow remains
across the CONUS with troughing in the east and ridging in the
west. At the surface a ridge axis was centered across eastern KS,
yielding clear skies and light winds across the area. The only
weather of note within the short term period is increasing cloud
cover overnight. WV analysis reveal a shortwave trough across
portions of Utah. Model solutions have the shortwave traversing
the CWA overnight into Thursday, only expect increasing mid-level
cloud cover. As the aforementioned surface ridge pushes into the
MS valley, southern flow will overspread the central Plains. With
the WAA and deep mixing up to H85 to H8 Thursday afternoon high
temperatures will range from the upper 60s in northern and far
eastern KS to the lower 70s in central KS. Southerly winds will
remain at 5-10 MPH with a few gusts up to 20 MPH, especially south
of I-70.

.LONG TERM...(Thursday night through Wednesday)
Issued at 356 PM CDT Wed Mar 21 2018

The next chance for precipitation arrives early Friday morning. A
lead shortwave is progged to eject into the central Plains Friday
afternoon/evening. Lee cyclogenesis will take place across eastern
CO, as a result increasing moisture advection will spread across
the CWA. Isentropic ascent within the 300-310K layer could yield
drizzle throughout the day Friday. NAM/GFS soundings maintain a
stout dry layer near H7, if precipitation is able to wet-bulb this
layer, rain showers and even thunderstorms would be likely Friday
afternoon. By Friday evening, forecast soundings greatly decrease
CIN for elevated parcels, therefore introduce thunder after 00Z
Saturday. NAM is the most bullish with instability with nearly
1,000 J/KG of MUcape. Effective shear values near 40 kts would
result in organized updrafts, contributing to a hail threat Friday
night if the NAM solution is correct. Surface ridge will
overspread the region on Saturday yielding slightly cooler
temperatures in the upper 50s and lower 60s Saturday afternoon.
Another shortwave trough is progged to eject from the base of the
cutoff low Monday. Lee troughing will develop across the high
Plains throughout the day Monday. WAA will once again overspread
the region late Sunday night into Monday. Isentropic ascent within
the 300-310K layer may yield drizzle into the day Monday, which
could play a big role in the amount of instability Monday
afternoon/evening. NAM/GFS/ECMWF solutions suggest upwards of
1,500 J/KG of MLcape will be present ahead of the front Monday
afternoon/evening. With sufficient deep shear remaining in place,
organized convection would be possible. Model solutions slowly
push the front southward throughout the day Tuesday. With good
moisture transport into the boundary, another round of shower and
thunderstorm activity is possible Tuesday.


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 645 PM CDT Wed Mar 21 2018

Little change to previous VFR forecast. Kept LLWS limited to MHK,
though did lower its level. Minor gusts possible after 14Z, more
likely at MHK.




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