Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 241728
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1228 PM CDT Thu Apr 24 2014

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 352 AM CDT THU APR 24 2014

08Z water vapor shows a longwave trough along the Rockies with two
distinct waves. The first over MT moving east and a second over
eastern NM. The overall progression of this upper trough has been
somewhat slower than earlier forecast. At the surface, a trough of
low pressure stretched from west TX through northeast KS. Low level
moisture was slow to return north, and surface dewpoints are just
now starting to show the low level moisture increasing across
southern KS. The forecast thinking this morning is that once the
vort max begins to lift northeast from the TX panhandle, showers and
thunderstorms will increase in intensity and coverage. This is
supported by the HRRR/RAP/NAM solutions and latest radar trends seem
to show stronger cells across central KS already. There is a good
deal of surface based CIN this morning, but mid level lapse rates
remain rather steep and there is some suggestion from the NAM and
GFS that the inhibition could weekend by late morning across east
central KS. So while widespread severe weather looks unlikely at
this time, there could still be an isolated strong storm with some
wind and/or hail. Because of the slower progression of the upper
trough, models are hanging onto precip later into the day. With the
main shortwave just moving towards the TX/OK panhandles, this seems
to make since and have delayed the clearing out of weather across
eastern KS until this afternoon. Also with clouds and precip hanging
around longer in the day with some cooler air moving in, have
adjusted today`s highs down a couple degrees with highs in the mid
60s to near 70.

By this evening, the upper trough axis should pass to the east of
the forecast area with dry air moving in from the west. Skies should
be mostly clear overnight with winds generally around 5 MPH. While I
don`t expect the boundary layer to completely decouple, there could
be enough radiational cooling with the dry air to allow temps to
fall into the lower and mid 40s.

.LONG TERM...(Friday through Wednesday)
Issued at 352 AM CDT THU APR 24 2014

Combination of mostly sunny skies...warm air advection and
strengthening south to southwest winds will push high temperatures
back into the upper 70s and lower 80s on Friday. strengthening llvl
jet will then veer and increase elevated moisture advection and
convergence across the southeast portions of the CWA through
sunrise Saturday...so will maintain low end pops across southeast
2/3 of the CWA to account for this. stronger mixing and slightly
higher dewpoints warmer overnight lows...generally in the middle
50s. By afternoon...a strengthening elevated mixed layer should
weaken/suppress convection over the eastern CWA while strong heating
to the west weakens the capping inversion with models indicating
initiation possible by mid/late afternoon with highs in the middle
80s over the southwest portions of the CWA. The EC is the most
aggressive with this scenario as a lead shortwave trough moves
northeast across the area with an expanding area of convection while
the other models show a stronger cap suppressing convection and
waiting until the evening/overnight for convection to the west
closer to the dryline to advance eastward. Either way...with
increasing bulk shear through the night west to east and strong
instability...any convection that is able to develop will have the
potential to become severe with very large hail...strong winds with
an afternoon/evening tornado potential with any convection coming
off the dryline to the west as a very strong upper trough rotates
north/northeastward into the central high plains through the
overnight into Sunday.

The upper level system is slightly slower and ejects out into the
high plains slightly further north and west. As a result there is
some question as to how quickly/aggressively the dryline will then
push eastward on Sunday with the EC the slowest with all modes of
severe weather once again possible over a greater portion of the CWA
than faster model solns which would limit that severe potential
farther east in the CWA. Will still maintain the highest pops across
the CWA Saturday night into Sunday period before lowering to chance
pops with the dry slot working into the CWA through Monday. Although
cooling aloft will still aid some destabilization...appears the
atmosphere will dry enough to warrant the removal of thunder from
the grids by late Tuesday night. Showers may still linger into
Wednesday before the upper trough finally shifts eastward. After the
warmest temps in the 80s on Saturday...will steadily cool highs
through the 70s Sunday...the 60s Monday then the 50s for both
Tuesday and Wednesday. Some upper 30s low temps still possible by
Wednesday morning.

&&

.AVIATION...(For the 18Z TAFs through 18Z Friday Afternoon)
Issued at 1224 PM CDT THU APR 24 2014

Showers and thunderstorms are currently exiting the area.
Conditions will quickly improve to VFR as the ceiling and
visibility increase. Mid level clouds should clear the taf sites
around 20-23Z. Winds will decrease around sunset only to pick up
again late tomorrow morning.

&&

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

$$

SHORT TERM...Wolters
LONG TERM...63
AVIATION...Sanders






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