Area Forecast Discussion
Issued by NWS Topeka, KS

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000
FXUS63 KTOP 301141
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
641 AM CDT SUN AUG 30 2015

...Update to aviation forecast discussion...

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 350 AM CDT SUN AUG 30 2015

Weak surface ridge over much of Kansas and rather saturated lower
few thousand feet allowing for areas of stratus and fog, though
enough wind remains for neither element to prevail. Latest
observations and 11-3.9 satellite imagery would suggest a trend to
more fog and will monitor trends for possible advisories. A slowly
increasing pressure gradient over the high plains should bring a
steady decrease in fog and stratus as winds pick up, but stayed
below most guidance for highs. Further increases in winds tonight
should keep any redevelopment of fog in check with again somewhat
warmer temps anticipated.

.LONG TERM...(Monday THROUGH Saturday)
ISSUED AT 350 AM CDT SUN AUG 30 2015

Monday through Friday, a positive tilt upper ridge axis will
extended from NM northeast into the upper midwest on Monday. by
mid week the ridge axis will flatten out due to shortwave trough moving
across southern Canada and the northern plains. The upper ridge
axis will remain in place across the southern half of the US.
Expect mostly dry conditions and warm temperatures in the upper
80s to lower 90s.

A weak h5 trough will round the ridge axis across NE and provide
enough ascent for scattered elevated storms across northern and
central NE Tuesday evening and through the night. I placed a
slight chance for thunderstorms Tuesday night along the NE border
in case the ascent and isentropic lift is strong enough across the
extreme northern counties for an isolated elevated shower or
thunderstorm.

Saturday, a broad upper level trough will amplify across the western
US and begin to slowly expand eastward. Both the ECMWF and GFS show
minor lead H5 troughs lifting northeast ahead ahead of the main
upper trough across the central high plains. There may be enough
ascent for isolated showers and storms across north central KS
Saturday afternoon, though the greater chances will occur across
western KS closer to the the surface lee trough axis. The better
chances for thunderstorms across the CWA will occur Sunday night
and Monday as the amplified upper trough across the western US
lifts northeast across the northern and central plains Sunday into
Monday.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z Monday MORNING)
ISSUED AT 641 AM CDT SUN AUG 30 2015

Timing and severity of stratus and fog are the main challenges.
Early view of 12Z sounding very close to model depictions of deep
moisture and expect mainly slow/minor improvements through 16Z
with VFR returning around 19Z. Given clear skies by 23Z, there
should be enough mixing after 02Z to keep a repeat fog/stratus
event in check.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY until 8 AM CDT this morning for KSZ008-009-
020-021-034-035-037.

&&

$$

SHORT TERM...65
LONG TERM...Gargan
AVIATION...65



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