322 
FXUS63 KTOP 202331
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
631 PM CDT Sun Oct 20 2019

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Monday)
Issued at 249 PM CDT Sun Oct 20 2019

An upper level trough was centered across the western NE PNHDL early 
this afternoon with a trough axis extending southward into the 
southern high Plains. A deepening surface low was located across 
southwest SD, with a surface cold front extending south-southeast 
and then southward across west central NE into west central KS, then 
extending southwest into the northern TX PNHDL.

This afternoon through Tonight, the upper trough will lift northeast 
across the central and southern Plains. DCVA ahead of the H5 trough 
axis will lead to strong ascent and as the surface cold front moves 
east, surface convergence combined with larger scale ascent will 
cause shower and scattered thunderstorms to develop along the front. 
The vertical wind shear profiles look quite favorable for severe 
thunderstorms. However, lack of rich moisture return will limit the 
instability in the warm sector ahead of the surface front across the 
CWA late this afternoon and evening. Some of the CAMS do show 500 to 
800 J/KG of MLCAPE developing towards 00Z MON. Given curving low-
level hodographs, resulting in streamwise horizontal vorticity, may 
provide for stronger vertical perturbation pressure gradients to 
cause thunderstorm updrafts to intensify despite having lower 
instability. Initially, there may be scattered thunderstorms 
developing along the cold front after 22Z across the west central 
counties but as the DCVA increases a line of storms may evolve 
through he evening hours along the front across the eastern 
counties of the CWA. Several CAMs show the low-level shear 
increasing after 00Z MON across the eastern counties of the CWA. If 
stronger surface based updraft do develop, then these updraft may 
rotate allowing for large hail and damaging wind gusts. The HRRR 
forecast 200-300 J/KG of 0-1 KM SRH developing by 00Z ahead of the 
surface front. Even if a line of storms were to develop, some of 
the updrafts embedded within the line may exhibit low-top 
supercell characteristics, but the main hazard may trend towards 
isolates severe wind gusts. So I cannot rule out some isolated 
weak tornadoes while storms remain scattered through the early 
afternoon hours or if a QLCS develops with meso vortices along 
the line.

Through the mid evening hours, as the boundary layer cools, 
the storms will probably weaken after 3Z and may become elevated. 
The surface front should move east of the CWA just after 6Z monday, 
bringing an end to the showers and storms. Surface winds will become 
west-northwest behind the surface front and overnight lows will drop 
into the 40s.

Monday the upper level trough will amplify as it lifts northeast 
into the upper Midwest with the H5 trough axis extending southward 
across MO into the LA/TX border region. West-northwest surface 
winds will increase through the mid morning hours and into the 
afternoon and become more northwesterly. wind speeds will increase
to 15 to 25 MPH with some gusts up to 40 MPH. If forecast mixing 
heights are a bit deeper across the western counties, then the 
northwest winds may exceed 30 MPH with gusts up to 45 MPH. The 
next forecast shift may have to issue a wind advisory for north 
central KS. Highs Monday will only reach the upper 50s to lower 
60s.

.LONG TERM...(Monday night through Sunday)
Issued at 249 PM CDT Sun Oct 20 2019

Monday night Through Wednesday, the northwest flow across the 
Plains will become zonal on Wednesday, as another H5 trough digs 
southeast into the central Rockies Wednesday afternoon. A broad 
surface ridge of high pressure will shift southeast into the gulf 
coast states. The northwest winds will diminish and veer to the 
southwest by Wednesday. Temperatures will warm slightly on 
Tuesday with highs reaching the lower to mid 60s. Wednesday's 
highs will reach the mid to upper 60s.

Wednesday night through Thursday, the H5 trough across the central 
Rockies will dig southeast across the Plains and begin to shear 
apart. The southern section of the H5 trough will amplify across 
west TX. A surface cold front will move southward across the CWA 
Wednesday night and become stationary across eastern OK and 
northwest AR. Light rain will develop north of the front as 
isentropic lift develops north of the surface front. Temperatures 
may get cold enough for light snow to mix in with the rain across 
the northwest counties of the CWA before ending during the morning 
hours of Thursday. The rain may linger across east central KS 
through Thursday afternoon but should shift southeast of the CWA as 
a surface low develops across east TX and moves east into LA. The 
Upper low across west TX will remain nearly stationary. Cloud cover 
with periods of light rain and low-level CAA will only allow highs 
to warm into the upper 40s to around 50 degrees.

Friday, a surface ridge of high pressure will build southwest into 
eastern KS. More insolation and diminishing surface winds will allow 
highs to warm into the mid to upper 50s.

Friday night through Saturday night, the upper low over west TX will 
get kicked northeast across southeast KS on Saturday, then northeast 
across the mid MS river valley by 12Z SUN. Periods of rain will 
develop late Friday night and extend through the day Saturday as 
DCVA provide stronger ascent. Cloud cover and rainshowers will 
probably only allow highs to reach the upper 40s to mid 50s. The 
rain should gradually end Saturday night as the  upper low tracks 
northeast across MO. AT this time, 850mb temperatures look to be 
in the 5 to 10 deg C range, so the precip will be all rain. There 
will not be much in the way of surface CAA.

Sunday, an upper level trough will dig south-southeast along the 
western US into the southwestern US, allowing the upper level flow
to become west-southwest across the Plains. Highs on Sunday will 
warm into the upper 50s to lower 60s with more insolation.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 630 PM CDT Sun Oct 20 2019

Scattered tsra will be possible at MHK terminal through 03Z and
then at TOP and FOE from 01Z to 05Z time period. Winds east
southeast becoming west in the 03Z to 05Z time period. Cigs mainly
vfr with a lowering to mvfr possible with tsra as well as mvfr
vsbys. Main concern will then will be strong winds from the west
developing after 12Z around 18kts with gusts to 28 kts, increasing
to around 23kts with gusts to 34 kts by 18Z. 

&&

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

$$

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