Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 010918
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
418 AM CDT Wed Apr 1 2015

.SHORT TERM...(Today and Tonight)
Issued at 401 AM CDT WED APR 1 2015

This morning, main PV anomaly was noted lifting eastward across Idaho.
This trough in conjunction with the weaker, embedded waves will
arrive into the Plains region late this afternoon. Additional
shortwave trough to have an impact on the area was noted lifting
northeast across west Texas this morning. Ongoing convection this
morning from OK into far southern KS will track south of the area
with mid level cloudiness clearing by mid morning.

Current obs show southerly winds already increasing between 10 and
15 mph near the Nebraska border in response to the deepening sfc
trough stretched over the western high plains. As the upper trough
approaches, strengthening southerly winds spread southward and
increase shortly after sunrise. Speeds between 15 and 25 mph
sustained are likely with gusts in excess of 30 mph. Should expect
the strong winds to persist until the cold front arrives from the
northwest this evening. A combination of strong warm advection and
mixing of h85 up to 17C boosts highs widespread in the lower 80s.
Thermal ridge axis edges over north central Kansas where locations may
reach the upper 80s. Fire weather concerns once again exist for this
afternoon. Please refer to the fire weather discussion below for
more information.

First area of focus is the slight chance for convection to develop
by late this afternoon over areas south of Interstate 35. Dewpoints
rise into the upper 50s to low 60s over southeast Kansas where
forecast soundings show the capping inversion eroding after 3 PM.
Decent forcing is provided by the upper trough progged by the latest
RUC/NAM to reach northeast OK between 1 PM and 7 PM. While
operational guidance has not hinted at this occurring, high
resolution guidance is similar in scattered convection developing
after 3 PM. Effective shear near 35 kts with Surface CAPE between
1500 and 2000 J/KG may result in a few strong to severe storms for
this area. Activity will quickly exit eastward into MO by early
evening. Isolated severe convection still remains possible along the
dryline forecast to setup over central Kansas between 4 PM and 7 PM.
Forecast soundings at CNK however hold onto the stronger capping
inversion until the main forcing arrives with the front between 7 PM
and 10 PM for north central KS where highest chances are placed.

Primary focus for convection is with the cold front shifting southeast
through the evening hours over northeast KS. Forcing for convection
lies above the inversion layer with steep mid level lapse rates
persisting through early Thursday morning. Optimal MU CAPE up to
2000 J/KG exists along and ahead of the boundary where 0-6 KM bulk
shear increases after midnight to 50 kts. Any convection that
develops in this area will be capable of large hail and damaging
wind gusts, especially after midnight when winds aloft increase to
60 kts. While activity is expected to move quickly through, some
redevelopment is possible with a secondary surge of energy from the
sfc trough over central KS. Training and/or redevelopment of
convection may bring periods of heavy rainfall across east central
portions of the area by sunrise Thursday.

.LONG TERM...(Thursday through Tuesday)
Issued at 401 AM CDT WED APR 1 2015

The surface front will have pushed just south of the forecast area
into southern Kansas by Thursday morning, but deep flow parallel to
the boundary will help it to stall on Thursday in advance of a
stronger short wave trough. By late Thursday, expect the front to be
located somewhere near or south of I-35 with steep mid level lapse
rates and low level moisture pooling contributing to modest surface
based instability near and south of the front. Wind shear will be
quite strong with an incoming jet streak associated with the short
wave, and the low level jet will increase a bit by late Thursday.
For the most part, the LLJ will focus into southeast KS and
southwest MO, but could see showers and storms develop into east
central KS as well during the evening hours. A few of these could
become strong near the front, with the main question being just
where that front will be...but the majority of strong storm activity
should be southeast of the forecast area.

Later Thursday night into Friday morning, the short wave trough
will make its way across Kansas while a reinforcing cold front
sweeps across the area. This combination will provide ample
forcing for ascent, but also expect a relatively dry airmass
especially over northern KS. Despite the dry air, the forcing
appears likely along with the presence of elevated convective
instability for rain showers to develop across northern and
eastern KS. Temperature profiles cool sharply as this rain falls,
but appear to stay just a bit too warm to support winter
precipitation so have kept the forecast all rain at this
time...but will want to keep an eye on far northern KS for a
potential mix if temps end up cooler.

Friday afternoon through the weekend will be dry, and Saturday
morning will likely flirt with freezing temperatures as high
pressure moves overhead. However, there is strong agreement that
southerly return flow will begin after midnight and may prevent a
hard freeze. Then expect warming into early next week as
southwesterly upper flow overspreads the region. Persistent
southerly flow will bring Gulf moisture back into the Plains, and
may provide a set up for a few chances of thunderstorms next week
coincident with weak short wave impulses moving through the
southwest flow. Shear and instability may align for one or more
of these periods to produce organized convection, but confidence
in when and where that may happen is quite low at this point.

&&

.AVIATION...(For the 06Z TAFs through 06Z Wednesday Night)
Issued at 1202 AM CDT WED APR 1 2015

VFR conditions expected through the period. Smoke may reduce
visibilities slightly at TAF sites toward morning but not enough
to change categories. Winds increase and become breezy Wednesday
morning.


&&

.FIRE WEATHER...
Issued at 401 AM CDT WED APR 1 2015

Very high fire danger conditions are anticipated once again this
afternoon for all of northeast Kansas. There exists some
uncertainity in the amount of moisture increasing into the area,
battling the drier air mixing down to the surface. East central KS
has the best chance for higher RH values with dewpoints in the upper
50s, resulting in 40 to 50 percent minimum RH. North central areas
however may see deeper mixing exhibited on some short term guidance,
leading to minimum RH near 30 percent. Widespread strong south winds
are of highest confidence where speeds between 15 and 25 mph and
gusts to 35 are expected from mid morning through early evening. A
cold front will arrive from the northwest between 7 PM and 10 PM in
the Concordia area, where northerly winds at 15 to 20 mph spread
southeast overnight. Will not issue headlines at this time due to
the higher RH values, but plan on monitoring for any slight changes
due to the relatively high winds above critical fuel areas.

&&

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

$$

SHORT TERM...Bowen
LONG TERM...Barjenbruch
AVIATION...67
FIRE WEATHER...Bowen






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