Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 251751
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1251 PM CDT Mon May 25 2015

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 315 AM CDT MON MAY 25 2015

Upper low over the Central Rockies continues to eject smaller pieces
of shortwave energy into Kansas, with one moving out of the forecast
area while the next is on approach. Steepening of lapse rates with
the incoming wave is providing enough instability for thunder to
develop, and model soundings indicate instability will continue to
be on the increase, along with an EML that moves into Eastern
Kansas.  Also of influence will be the convective complex out in
west central Kansas moving eastward at this hour.  The northern side
of this feature appears to have gust front out ahead of the
convection while the southern side still is along or just behind the
gust front. Latest HRRR dissipates this feature considerably through
the early morning hours, and at this time have opted to carry
diminishing precip chances through the morning to account for this
feature.  The Cottonwood, Neosho, and Marias des Cygnes rivers
continue to be in flood, but at this time don`t see lingering heavy
rainfall and will cancel the flash flood watch. Afternoon hours
appear to be a transition period as EML moves in and perhaps
subsidence behind leading shortwave aid in clearing out earlier
convection, a reset for activity in the late afternoon and evening
hours.

Larger scale upper trof moves eastward late this afternoon and
evening, bring surface low and frontal boundary into north central
Kansas.  Lapse rates continue to steepen along this boundary, with
NAM12 indicating 2500J/kg of surface based CAPE by 23z near
Concordia, and higher values toward Manhattan, although think this
is somewhat overdone by high dewpoint bias in that area.  0-1km shear
values are in the 10-20kt range, with 0-3km helicity near 150m/s2.
0-6km bulk shear values are less robust, around 25kts, with wind
speeds aloft weaker and more unidirectional making for weaker
profiles. Still enough ingredients to make severe hail and wind of
concern with storms that develop, along with potential for isolated
tornadoes, and has led to an outlook from SPC for a slight risk
across mainly the northwest half of our area.  Despite rain chances
early and late, high temperatures still expected to make it back
into the upper 70s. As upper system moves eastward late evening and
overnight, have continued thunderstorm chances across the area, some
of which may continue to be strong to severe.

.LONG TERM...(Tuesday through Sunday)
Issued at 315 AM CDT MON MAY 25 2015

By Tuesday morning the main shortwave trough should be lifting into
the upper Midwest, although there are some hints of some weak energy
hanging back across the central and southern plains. As this energy
potentially moves over the region a few of the models are generating
light QPF Tuesday afternoon and overnight with the lack of CIN, but
there is not much focus for lift. On Wednesday after some slight
mid level ridging moves east of the Rockies the lee side trough
develops and return flow becomes better established. Any
thunderstorm complexes that develop over the high plains have a
chance of moving eastward into the forecast area Wednesday through
Thursday night. Then a stronger shortwave drops out of the pacific
northwest into the central Rockies Thursday. As it lifts over the
plains on Friday and Saturday the chances for precip increases,
which has been a consistent solution for the past few days, so
will continue with the likely pops. The GFS is more aggressive
with tracking a decent surface low pressure over eastern KS, while
the ECMWF just brings a robust front through. Either way another
shot of widespread measurable rain looks to be on track for early
next weekend.

&&

.AVIATION...(For the 18Z TAFs through 18Z Tuesday Afternoon)
Issued at 1238 PM CDT MON MAY 25 2015

This forecast period is another tricky setup. Cloud cover should
help limit convection, however, there is a good likelihood that
some convection does develop mainly from Central KS into
northeastern KS later this afternoon. This could impact the
terminals but left VCTS for now. Any activity should end shortly
after sunset this evening. In the meantime, good confidence that
winds will continue out of the South and remain gusty as there has
been some decent mixing taking place. The second half of the TAF
period should be more settled, but still a minor chance of morning
storms perhaps over North central KS into NE.

&&

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

$$

SHORT TERM...67
LONG TERM...Sanders
AVIATION...Drake






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