105
FXUS63 KTOP 161731
AFDTOP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1231 PM CDT Wed Oct 16 2013
...Update to aviation forecast discussion...
.SHORT TERM...(Today and Tonight)
Issued at 328 AM CDT WED OCT 16 2013
Water vapor satellite loop shows an upper level low pressure trough
over the Rockies at 08Z with a dry slot across southern and eastern
Kansas. At the surface, high pressure was located across the Western
High Plains.
Clouds continued to move across most of the forecast area early this
morning. The stratus was starting to erode in south central
Nebraska. Models show the moisture in the 925 mb to 800 mb
decreasing through the morning, clearing out about the southern
2/3rds of the forecast area. Clouds will again increase this
afternoon as the upper trough moves out across the Plains, mid level
relative humidity values are forecast to increase. The high pressure
across the High Plains will move southeast through the day into
Oklahoma. Highs today will remain below seasonal values in the upper
50s.
Tonight, the upper trough will move across Kansas with the trough
axis moving east of northeast and east central Kansas after 06Z.
Best forcing, mid level frontogenesis, and moisture will be just
southeast of the CWA. Will leave in sprinkles southeast of
Interstate 35 for the evening hours. Clouds will be on the decrease
from west to east after midnight clearing the east central counties
by 12Z Thursday. Return flow later tonight will keep the lower
boundary layer mixed out in north central Kansas keeping frost at
bay. Lows tonight will range from the mid 30s in far north central
Kansas to the lower 40s southeast of I-35.
.LONG TERM...(Thursday through Tuesday)
Issued at 328 AM CDT WED OCT 16 2013
By Thursday, a mid-level low will be in place over central Canada
with a mid-level trough extending southward into the Northern
Plains. Conditions will remain dry on Thursday as surface high
pressure sits over the Rockies and extends into the Southern Plains.
With mostly sunny skies in place and light west-southwesterly winds,
Thursday looks to be the warmest day of the week as temperatures
reach closer to normal with highs into the middle/upper 60s. For Thursday
night, the mid-level trough will deepen further south toward the
Central Plains. With surface low pressure situated near the Great
Lakes region, this deepening trough will actually help to push a
weak cold front southward across the cwa late Thursday afternoon
through Thursday evening. However, do not anticipate any
precipitation developing with this frontal passage due to limited
available moisture. The only thing of note from model soundings is
that the region should see an increase in mid- and high-level clouds
as the front moves through the area. Despite winds shifting to the
northwest behind the front, the increased cloud cover should keep
temperatures Thursday night a couple of degrees warmer into the
lower 40s.
By Friday, models show a weak embedded shortwave developing within
the mid-level trough. This wave will move southward across western
Kansas during the day, rounding out over southern Kansas/northern
Oklahoma Friday evening. It looks like some Gulf of Mexico moisture
may be able to stream northward into this wave to provide more
available moisture. This available moisture combined with some
modest lift could result in some showers developing through the day
and possibly into the early evening hours, primarily across central
and east central Kansas. With the increased cloud cover in place,
high temperatures are expected to drop back down into the
middle/upper 50s. This cloud cover is expected to diminish Friday
night, resulting in decent radiational cooling and low temperatures
plummeting into the upper 30s.
For this weekend into early next week, the broad, expansive
mid-level trough will continue to stretch across much of the central
and eastern U.S. as a mid-level ridge remains anchored over the
Pacific Ocean. Models continue to highlight the potential for a few
embedded shortwaves to develop along the western edge of this trough
and slide southward toward the area during the Sunday night through
Tuesday timeframe. However, there are model discrepancies with
regards to the timing and tracking of any of these waves that may
develop as well as uncertainty with how much moisture would actually
be available. The GFS is the most aggressive of the models in
bringing a shortwave through Sunday night into Monday. But due to these
various uncertainties, have kept the forecast dry through the
weekend and into the early part of next week and will continue to
monitor future model trends. During this timeframe, temperatures
will be fairly consistent but still remain a few degrees cooler than
normal. High temperatures should reach into the lower/middle 60s
with low temperatures bottoming out in the lower/middle 40s.
&&
.AVIATION...(For the 18Z TAFs through 18Z Thursday Afternoon)
Issued at 1230 PM CDT WED OCT 16 2013
VFR conditions expected through the period. Added a line for what
should be a pretty solid mid level deck, and will need to monitor
for possible vicinity showers, but have dry TAF at this time.
Winds shift from NW to W through the period.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...53
LONG TERM...Hennecke
AVIATION...67