Area Forecast Discussion
Issued by NWS Topeka, KS

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000
FXUS63 KTOP 160914
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
414 AM CDT Wed Apr 16 2014

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 330 AM CDT WED APR 16 2014

A much warmer and windy day is expected across northeast Kansas.
Main highlights include the strong winds and extreme fire danger
conditions beginning later this morning.

At 2 AM, the surface trough was centered over southern South Dakota.
Surface winds from the south have been increasing overnight as a 60
kt LLJ at 925 MB ahead of the trough resides over the region. The
h85 jet streak maximizes just ahead of the h85 front tracking
southeastward through the day across the area. Should expect these
winds to mix down to the surface through the morning hours across
far north central Kansas with gusts near 35 mph possible. As diurnal
heating commences during the mid morning hours, steepening lapse
rates and strong momentum transfer aloft from the passing surface
trough will increase winds between 25 and 35 mph sustained, gusting
over 40 mph across most of northeast and east central Kansas. A Wind
Advisory has been issued from mid morning through early evening. As
the surface front approaches the Kansas and Nebraska border by the
afternoon, wind speeds wane to around 15 mph sustained. This trend
continues southeastward with the stronger wind gusts diminishing
near 6 PM across east central areas. Ample warm advection on the h85
surface will allow high temperatures to rise into the middle and
upper 60s. A few locations may even reach the 70 degree mark if
slightly better mixing to the surface is achieved. In terms of fire
weather, dew point temps this morning in the teens across north
central Kansas to the mid and upper 20s elsewhere will not deviate
much through the afternoon as the boundary layer stays mixed. The
critical fuels, lower humidity, and gusty winds will create extreme
fire danger conditions for a good portion of the area. Please refer
to the Fire Weather Section below for more details.

Short term guidance progs the surface front to be through northeast
Kansas by 3 AM Thursday morning. The pressure gradient tightens just
behind the boundary as north winds sustain between 10 and 15 mph.
Gusts up to 20 mph remain possible over north central and far
northeast Kansas. A weaker upper shortwave trough enters the central
plains after midnight noted by mid level clouds increasing
overnight. This insulation will hold lows near 40 degrees south of
Interstate 70. Further north, mostly clear skies will cool lows to
the low and middle 30s.

.LONG TERM...(Thursday through Tuesday)
Issued at 330 AM CDT WED APR 16 2014

By early Thursday morning, the cold front will have stalled over far
southern KS with cold and dry advection across the local area. A
weak short wave trough will move across KS between 12Z and 00Z. This
wave will help enhance mid level frontogenesis across southern into
east central KS and also provide moderate QG forcing across the same
area. At the same time, the airmass across the area will be very dry
in advance of the system, and reinforcing dry advection through the
period will make it difficult for precipitation developing aloft to
reach the surface. Strangely, forecast soundings do not saturate
fully even in models that are predicting moderate precipitation.
Given the dry air issues, have cut back dramatically on POPs across
the entire area with much of the northern counties now having a dry
forecast while the east central KS counties still have a 40-50%
chance of precip at the peak of the event on Thursday. Even in areas
where rain falls, expect it to be very light.

Friday finds the local area in a warm advection pattern with
sunshine and deep mixing expected. Have increased forecast temps for
Friday and Friday night given these factors, with some potential for
Friday to be a bit warmer yet depending on just how strong the warm
advection into the area is. It will be dry through Friday night.

The next storm system will move across the area beginning late
Saturday. This is a two-part system with one short wave tracking
across the US/Canada border while a second piece of energy moves
east out of southern California. The key to this period of the
forecast seems to be in whether or not the two pieces of energy will
phase a bit or if they`ll be separated enough to not interact. For
instance, the 00Z GFS moves the two systems across the Plains at
similar times, resulting in a quicker end to precip by late Sunday.
Meanwhile, the 00Z ECMWF has zonal flow between the two troughs with
little to no interaction, resulting in a slower progression of the
southern trough and prolonged precipitation chances across the
region as it meanders east. For this forecast, have actually gone
with the slightly quicker exit of precip as this seems to be favored
by the majority of guidance. Chances look quite good as there will
be plenty of moisture to work with along with frontal and upper
level forcing mechanisms. Instability is not particularly
impressive, but may be sufficient for periods of thunderstorms
through Sunday. Temperatures should remain near normal through the
period despite ample cloud cover, and then expect warmer conditions
by Tuesday as any cold advection with the storm system will be weak.
Attention then turns to an incoming potentially strong storm system
by mid to late week.

&&

.AVIATION...(For the 06Z TAFs through 06Z Thursday Morning) Issued
at 409 AM CDT WED APR 16 2014

Surface winds the past few hours at KTOP have weakened to around
12 kts with occasional gusts near 20 kts. 400 feet off the
surface, a strong low level jet near 55 kts was observed. Have
amended to add LLWS possible for the next few hours before
sustained surface winds increase. Previous discussion from last
issuance is shown below.

VFR conditions anticipated through the taf period. Boundary layer
mixing overnight should be enough to keep the smoke from
restricting the visibilities although can not rule out a brief
period of MVFR vis reported by the ASOS due to smoke. There will
be a period tomorrow around 13-15Z where gusts could exceed 40kt
at the surface with a gradual decrease through the afternoon. Then
a wind shift associated with a passing trough followed by speeds
slightly increasing during the evening hours.

&&

.FIRE WEATHER...
Issued at 409 AM CDT WED APR 16 2014

A Red Flag warning is in effect for much of northeast and east
central Kansas from 10 AM through 6 PM today. South winds this
morning are observed between 15 and 25 mph sustained with occasional
gusts near 30 mph. Should expect the south winds to increase between
25 and 35 mph sustained with gusts in upwards of 40 mph after 10 AM
this morning. A cold front will enter the Kansas and Nebraska border
after 1 PM, switching wind direction towards the southwest as the
boundary approaches. Speeds wane slightly between 15 and 20 mph with
gusts near 25 mph over north central areas by late afternoon, and by
early evening over far east central Kansas. Fire weather partners
have requested the warning due to the strong winds making any fire
very difficult, if not impossible, to control. RH values through the
morning and afternoon are close to critical levels in the lower to
middle 20 percentile in the afternoon.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING from 10 AM this morning to 6 PM CDT this
evening FOR KSZ009>012-021>024-026-035>040-054>056-058-059.

WIND ADVISORY from 10 AM this morning to 6 PM CDT this evening
FOR KSZ010>012-022>024-026-036>040-054>056-058-059.

&&

$$

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





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