Area Forecast Discussion
Issued by NWS Topeka, KS

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000
FXUS63 KTOP 180126
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
826 PM CDT Sun Aug 17 2014

.UPDATE...
Issued at 812 PM CDT SUN AUG 17 2014

Monitoring two MCS complexes tracking southeast over southern
Nebraska and north central Kansas. The Nebraska cluster maintains
a strong outflow boundary around 50 MPH gusting out ahead of the
main line showing a history of 60 to 70 mph winds. Thunderstorm
cluster in Kansas has recently reported wind gusts near 60 mph.
Environment ahead of the system is characterized currently by 3500
J/KG of MLCAPE and effective shear increasing to near 30 KTS as a
southwesterly LLJ ramps up over north central Kansas. Current thinking
is similar to latest runs of the HRRR depicting the two clusters
converging as they track south and east over the CWA. Have therefore
increased precip chances over north central Kansas. Instability gradient
weakens towards central and eastern portions of northeast Kansas
and would expect the cluster to weaken in severity between
midnight and 7 AM. Between now and midnight, slight risk of severe
weather was expanded across north central areas where wind gusts
between 50 and 60 mph and small hail are possible.

&&

.SHORT TERM...(This Evening through Monday)
Issued at 343 PM CDT SUN AUG 17 2014

Water vapor imagery showing next shortwave trough and associated
frontal boundary moving thru northwest NE. Thunderstorms have
developed over north central NE and should propagate southeastward
within moisture axis situated across central NE into far northern
KS that will lift slowly northward through the night. Expect NE
convection to weaken later this evening with the loss of heating and
weaker shear further south towards the KS border. Will still however
keep the high chance pops near the NE border and decrease southward
in weaker warm air advection. The most likely period will be near
the state line towards sunrise in the far northeast corner. Lows
tonight will be in the middle to upper 60s. More mixing and
increasing clouds should limit fog potential tonight.

Front to the north will move southeast and bisect the cwa northeast
to southwest by mid to late afternoon. Axis of higher cape will set
up along and ahead of the front. Although the shear along the front
will not be as strong as further north and a capping inversion will
be in place...expect afternoon heating and weak convergence along
the front to allow at least some isolated thunderstorms to develop.
If they do...a deeply mixed atmosphere with temps well into the
middle and upper 90s would favor potential strong wind gusts with
any convection that forms. Will keep highest chance pops along and
ahead of the front...or primarily just north and west of the
Turnpike.

.LONG TERM...(Monday Night through Sunday)
Issued at 343 PM CDT SUN AUG 17 2014

Expect scattered convection Monday evening as the frontal along the
frontal boundary as it slowly moves southeast. NAM showing MUCAPE
around 5000 J/KG with around 35 to 40kts of bulk shear into the
early evening hours. Could see a few strong to severe storms with
strong wind gusts the main hazard. The front should sag south of the
CWA Tuesday morning before moving northward as a warm front Tuesday
afternoon and Tuesday night. Isentropic lift over the warm front
should generate elevated thunderstorms mainly across the northern
CWA. Areas near Highway 36 will have a small chance of morning
thunderstorms on Wednesday.

Wednesday night through Saturday will see ridge building over the
Southern and Central Plains. Periodic waves will move through the
flow and models differ on timing and resultant precipitation
placement. Will continue with low end chances of precipitation,
mainly nocturnal. GFS and ECMWF diverge with the timing of an upper
level trough with the GFS keeping the upper trough over the western
states while the ECMWF is much further east over the central U.S..
Will go dry on Sunday given the large differences for now.

Temperatures will be above normal through much of the period.

&&

.AVIATION...(For the 00Z TAFs through 00Z Monday Evening)
Issued at 638 PM CDT SUN AUG 17 2014

Monitoring the evolution of TSRA over western Kansas and central
Nebraska. Latest guidance is beginning to trend toward convection
weakening west of KMHK by 12Z. Confidence was not high enough to
mention thunder at KMHK at this time. Second concern is fog
potential before cloud cover arrives. MVFR to IFR fog is possible
at KTOP after 09Z while increased winds and cloud cover at KMHK/KFOE
may hinder lower visibilities. Fog is expected to dissipate around
14Z as mixing increases.


&&

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

$$

UPDATE...Bowen
SHORT TERM...63
LONG TERM...53
AVIATION...Bowen






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