Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 010503
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1203 AM CDT Wed Apr 1 2015

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Wednesday)
Issued at 339 PM CDT TUE MAR 31 2015

20Z water vapor shows shortwave ridging over the central Rockies
into the northern plains with a broad trough over New England and
another upper trough moving inland of across the Pacific
northeast. a closed upper low was moving east across northern
Mexico. At the surface, a broad area of high pressure spanned the
middle MO and middle MS river valleys. But deeper moisture with
dewpoints in the 60s, is not that far south over OK and AR.

With shortwave ridging affecting the area tonight and into Wednesday
morning, there is not expected to be any sensible weather. As the
surface ridge passes east, the deeper moisture is expected to move
back north late tonight and through the day Wednesday. There may be
some increasing cloud cover late tonight due to the moisture return.
This along with an increasing pressure gradient is expected to keep
overnight lows up into the lower and mid 50s. For Wednesday
afternoon, the models show higher dewpoints advecting north through
northeast KS. The NAM is a little slower in advecting an elevated
mixed layer (EML) into the area and generates some good surface
based instability. However there is nothing to lift a surface parcel
and no real forcing to increase vertical motion. Additionally the
GFS continues to show a much stronger EML keeping a good cap over
the boundary layer. Therefore have kept a dry forecast through 6 PM
thinking thunderstorms will hold off until the front moves through
providing some lift. An increasing pressure gradient and deep mixing
should cause south winds to gust over 30 mph. Have continued to go
above guidance with highs anticipating good mixing pushing highs
into the lower and mid 80s.

.LONG TERM...(Wednesday Night through Tuesday)
Issued at 339 PM CDT TUE MAR 31 2015

Potential for severe weather remains, though a continued slightly
slower trend continues to show itself. Convective should fire well
west and north of the area late Wednesday afternoon, mainly along the
front but perhaps a few along the dryline. South to southwest winds
will likely stay rather strong into the early evening, helping keep
some instability for lower level parcels, but leaning closer to the
GFS than NAM on lower level moisture, instability and shear would
seem to support some opportunity for severe weather, though limited
winds aloft and shear vectors oriented near the boundary,
well-organized storms chances seem to be diminishing for the local
area. Still have good opportunity for convection as the front
continues south, at least for northern and central areas. Thursday
brings drying conditions, but how much cloud lingers remains in
question and will play a significant role in temps and have dropped
values a bit. Still appears light precip from a second round of
convection is possible with the second upper trough with rather
strong baroclinic zone under 140kt jet aloft. Models continue to
have discrepancies on how much isentropic lift will be realized and
specifics on where the better chances will be differ. Will also need
to watch thermodynamic trends in the north with deepening cold air
potential leading to snow to reach the ground. Rapid drying takes
place Friday but AM cold air advection brings temps down into the
50s, with frost still possible Friday night. Faster upper flow over
the southern CONUS into early next week, with upper ridging Saturday
into Sunday, leading to some  moisture and minor precipitation
chances via weak forcing early next week.

&&

.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.

&&

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

$$

SHORT TERM...Wolters
LONG TERM...65
AVIATION...67






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