Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 060428

Area Forecast Discussion
National Weather Service Topeka KS
1128 PM CDT Fri Jun 5 2020

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Saturday)
Issued at 305 PM CDT Fri Jun 5 2020

Sfc pressure rises noted this afternoon as the upper ridge builds
eastward into the southern plains this afternoon. Cloud cover
associated with the MCS earlier this morning has cleared the
forecast area, allowing temps to quickly warm into the lower 90s.
Coupled with dewpoints around 70 degrees, heat indices in the low
100s are being observed across portions of north central Kansas.
Observational analysis shows the diffuse boundary situated near
the Interstate 70 corridor while sfc based CAPE is forecast to
reach in excess of 4000 J/KG, a weak EML around 800 mb and lack of
any apparent embedded waves or focused forcing should preclude
storm development this afternoon. Have maintained a 10 percent
chance, and given the environment, any storm that develops would
be severe with hail and damaging winds the main hazards.

Quiet conditions anticipated this evening as the area becomes more
centered underneath the high pressure, focusing convection further
north and east of the region. Other than a few passing high clouds,
skies are mostly clear with overnight lows in the lower 70s.

The more widespread concern for the forecast is the heat on
Saturday. Low level mixing is stronger as a lee trough
strengthens to our west, gusting southerly winds in excess of 20
mph throughout the afternoon. Forecast soundings suggest we could
mix 925 MB temps of 27C to the sfc, resulting in highs from the
mid to upper 90s. In addition, moisture advects northward ahead of
a dry line in central KS where dewpoints are likely to reach the
low to mid 70s before some drier air mixes downward in north
central areas. Overall, this would result in heat indices up to
105 degrees. Therefore, went ahead and issued a Heat Advisory for
tomorrow afternoon given that its the first event of the year and
a weekend. I held off on an advisory for the northern tier of
counties near the Nebraska border, given the slightly lower temps
with heat indices in the 99 to 100 degree range.

.LONG TERM...(Saturday night through Friday)
Issued at 305 PM CDT Fri Jun 5 2020

The heat continues Sunday with no major change in the
upper air pattern as the upper ridge gradually slides eastward.
Dewpoints are not as high on Sunday compared to Saturday, however
heat indices around 100 still appear likely. Also increased winds
Sunday as the sfc pressure gradient tightens with the deepening low
off the western high plains. On Monday, low level winds back to the
southeast in response to Tropical Storm Cristobal coming onshore.
Temps are therefore not as high with readings in the low 90s and
heat indices in the middle to upper 90s. Timing of the incoming
upper trough from the west will determine the path of Cristobal and
it`s overall impacts on eastern CWA. Latest forecast package favors
the path of the TS to mainly impact MO. The 12Z ECMWF however is a
bit slower with the incoming wave, allowing Cristobal to bring
showers and storms to far eastern Kansas Tuesday. Rainfall amounts
are highly dependent on the path, with heavy rainfall concerns more
likely in MO.

Showers and storms are also expected to develop along a strong cold
front Tuesday afternoon and evening, clearing the area northwest to
southeast by Tuesday evening. Much cooler and pleasant conditions
return to the area Wednesday onward as high temps return to the 80s
with overnight lows in the lower 60s.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1127 PM CDT Fri Jun 5 2020

Expect VFR conditions across all the terminals through the next 24
hours. The thunderstorms across far western NE late this evening will
will track east across central and northern NE through the night,
well north of the terminals.


Heat Advisory from 1 PM to 7 PM CDT Saturday for KSZ021>024-026-



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