Area Forecast Discussion
Issued by NWS Topeka, KS

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000
FXUS63 KTOP 201054
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
554 AM CDT Fri Sep 20 2019

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 339 AM CDT Fri Sep 20 2019

Early this morning an upper level trough was located over the
western U.S. while a ridge extended across the eastern Plains south
into the Gulf. Weak embedded waves were moving northeast out of the
base of the trough and into western Kansas south into eastern New
Mexico where scattered convection was occurring at 0730Z. Latest
surface analysis showed an area of 70 degree or higher dew points
from the Red River south into Texas, while central and eastern
Kansas had dew points in the 60s.

For today, remnant PV anomalies will move northeast across the area
today. Forecast soundings show a weakly sheared environment and
moderate instability through the day into the early evening hours.
CAMS continue to develop isolated to scattered convection over parts
of north central and northeast Kansas today and into tonight as the
perturbations move northeast, moisture advection increases with the
increasing low level jet. Have maintained lower end precipitation
chances through the day and into tonight. Temperatures today will be
limited in the lower to mid 80s dues to clouds limiting insolation.

Saturday, a cold front is forecast to extend from northwest Iowa
into south central Nebraska into southwest Kansas by late afternoon.
The lead trough is forecast to lift northeast into the northern
Plains on Saturday which will move the front further south. Airmass
ahead of the front becomes very unstable and deep layer moisture
increases across central and eastern Kansas with precipitable water
increasing to around two inches. Shear will be sufficient for severe
storms and forecast hodographs and SRH values are favorable enough
to mention an isolated tornado possibility, especially during the
early evening hours.

.LONG TERM...(Saturday through Thursday)
Issued at 339 AM CDT Fri Sep 20 2019

Next main concern will be heavy rainfall potential across much of
northeast and east central Kansas Saturday night into Sunday
morning. Forecast soundings show deep moisture profiles. Theta-e
ridge will lay from southwest to northeast across the area. Forcing
for ascent will increase as the upper trough moves out into the
Plains. Also the presence of the entrance region of the upper level
jet will increase upward vertical motion and upper level divergence.
Training of storms will lead to locally heavy rainfall with amounts
of 2 to 4 inches and locally higher possible through mid day Sunday.
Axis of heaviest rain may shift a bit, but confident enough to issue
a Flash Flood Watch from Saturday evening into early Sunday
afternoon.

Looking ahead models differ some with respect to another upper look
digging into the southwest U. S. early next week and the timing and
track as it moves out into the plains by the end of the week. SOme
timing differences also with a lead wave moving through the central
Plains on Tuesday. Nearly Zonal to southwest flow develops by
midweek as the upper low then is forecast to move out into the
Plains. This will keep small chances of precipitation in the
forecast although there will be periods of dry weather. Temperatures
will be around seasonal values.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 554 AM CDT Fri Sep 20 2019

VFR conditions are expected through 20Z with cigs then lowering to
mvfr as stratus develops and moves into the TOP and FOE areas,
then into the MHK area by 01Z Saturday. Isolated to scattered
convection is possible after 19Z through 01Z and added vcts. Some
ifr cigs are possible toward the end of the period at FOE and TOP.
Winds increasing from the south after 18Z around 12 kts with gusts
to around 23 kts, decreasing to around 10 kts after 00Z Saturday.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch from Saturday evening through Sunday afternoon
for KSZ010>012-022>024-026-035>040-054>056.

&&

$$

SHORT TERM...53
LONG TERM...53
AVIATION...53


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