Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 270516

1116 PM CST Mon Jan 26 2015

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Tuesday)
Issued at 310 PM CST MON JAN 26 2015

A deep upper level trough across the eastern US will amplify tonight
along the eastern seaboard, providing the northeast US with several
hours of very heavy snowfall Tonight through Wednesday.

This afternoon, temperatures have warmed into the mid to upper 60s
across the CWA. West central KS has warmed into the lower 70s as
downslope warming across the central high plains is advected
southeast across western and central KS.

As the eastern US trough amplifies, low-level CAA develop from the
upper Midwest across the Great Lakes States and southward across the
MS and OH river valleys. As a result of increase low-level CAA a
surface ridge will build southward across the MO river valley. The
western edge of the sfc ridge will be across eastern KS Tuesday
morning and then will slide east int MO. Farther west a lee side
surface trough will develop across eastern CO. Surface winds across
the CWA Tuesday morning will be light from the northeast and east,
then gradually become southeasterly through the afternoon hours.
southeast surface winds across the western counties of the CWA may
increase to 15 MPH with gusts of 20 to 25 MPH possible during the
mid and late afternoon hours. Forecast soundings show the boundary
layer only mixing to about 950MB across the eastern half of the CWA,
therefore, I kept Highs a bit cooler on Tuesday with mid 50s to to
around 60 degrees across northeast and east central KS. During the
afternoon hours there will be quite the gradient in temperatures at
850mb with 16 deg C 850 temps across north central KS and 7 deg C
850 temps in extreme northeast KS. Ottawa County may reach near 70
degrees with deeper mixing to 925MB.

.LONG TERM...(Tuesday Night through Monday)
Issued at 310 PM CST MON JAN 26 2015

Progressive shortwave trough flattens ridge over central U.S. and
brings warm advection and mixing Tuesday night.  This should keep
lows in the upper 30s to lower 40s.  Very warm day expected again
for Wednesday with southwesterly low-level flow turning to westerly,
and highs mainly in the 60s.  Cold advection then follows for
Wednesday night, but mixing and relatively mild post-frontal airmass
will still keep lows in the 30s.  Continued cold advection on
Thursday will make for a cooler day with highs in the 40s.

Surface high pressure ridge moves across the area Thursday night and
Friday with cooler temps, which will still be above the normals for
this time of year.

Medium range models then bring lift ahead of another system across
the area beginning Friday night and continuing through Saturday
night.  Details on speed of system as well as potential phasing of
northern and southern stream troughs varies amongst the models, with
GFS runs typically faster, and GEM and ECMWF slower.  Suffice to say
that chances for precip will increase from southwest to northeast
Friday night, with a decent chance of rain and snow on Saturday,
then changing over to all snow Saturday night.  If ECMWF is closer
to reality with its slower forecast, precip could hang on into
Sunday morning.  Precip type a little tricky as precip arrives with
warming so there could be a chance of snow, then turning to rain, or
a mix of rain and snow for Saturday, then turning back over to all
snow Saturday night.  Amounts will be very dependent on how much of
the QPF falls as snow, but some accumulation would be expected.

Colder air behind this system will bring near normal temperatures
for Sunday and Monday.


.AVIATION...(For the 06Z TAFs through 06Z Tuesday Night)
Issued at 1115 PM CST MON JAN 26 2015

VFR conditions expected through the period. Light winds overnight
become southeast on Monday and are expected to remain generally
below 12kts.




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