Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 270010 AAA
AFDTOP

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TOPEKA KS
710 PM CDT Thu Mar 26 2015

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Friday)
Issued at 324 PM CDT THU MAR 26 2015

Weak upper trough this afternoon continues to push southeast
across South Dakota into northern Nebraska. Where stratus clouds
have held for much of the day, bands of rain and snow were
impacting central and eastern portions of Nebraska. Across
northeast Kansas, mid level clouds were increasing from the north
as influence from the surface trough to the east has kept
northerly winds on the gusty side over eastern Kansas. Elsewhere,
winds are light with highs today on the cool side in the lower
50s.

Weak perturbation slides southeast towards the CWA this evening
bringing a good chance for rain showers to develop across portions
of northeast and east central Kansas. Best period for measurable
precipitation appears to be from 7 PM through 1 AM where near a
tenth of an inch of rainfall is possible. Fortunately, most of the
precip is expected to fall while temps are above freezing. Areas
east of highway 75 and north of interstate 70 may see some lingering
light rain mix with light snow or flurries after midnight as the
precip exits to the east. Increasing mid level subsidence lessens the
chance of this occurring as the stronger lift shifts east. Warm
ground temps warrant no concerns of accumulation.

Cool surface ridge builds in on Friday as light winds and mixing
will make it difficult for stratus to clear out before the next
system and mid level clouds arrive from the northwest. With the
partly to mostly cloudy skies and no strong signal of temperature
advection, have lowered highs especially over north central areas
down to the lower 50s.

.LONG TERM...(Friday Night through Thursday)
Issued at 324 PM CDT THU MAR 26 2015

For Friday night through Sunday, models continue to show weak
shortwaves within northwest flow aloft potentially clipping
northeast KS. The main uncertainty in this period is with the
shortwave on Sunday as the ECMWF/GEM show a more amplified wave
and slower progression with a frontal boundary while the GFS and
NAM weaken the wave as it moves through Sunday morning. Have
tended to go with a middle of the road forecast for Sunday holding
onto small POPs through the day across northeast and east central
KS since ECMWF ensemble data are a little more amplified than the
GFS but not as slow as the ECMWF. Nevertheless temps appear to be
warm enough for any precip to be rain late Saturday night and
Sunday. For Friday night, there is a small chance that there could
be a few snow flakes mix in with light rain. Forecast soundings
show surface temps above freezing Friday night, but wet bulb
cooling may allow for a brief mix of snow. General warm air
advection expected at 850MB with temps warming above 0C should
ensure any snow to have little or no impact. For temps have
trended highs down a couple degrees. Models show low level winds
remaining from the southeast on Saturday while 850MB temp
advection is modest. 850MB temps do not change much for Sunday
with possible frontal boundary moving through so think highs will
remain in the 60s.

Monday and Tuesday are expected to remain dry since there is not
obvious forcing for precip progged by the models, however there
may be a weak boundary move through the area. The GFS is more
aggressive with the boundary Tuesday. However the better forcing
and moisture are expected to remain south of the forecast area so
even if the boundary is able to maintain some definition, think
precip would be hard to come by as lift would be weak at best and
have kept a dry forecast.

A little better front is progged to move through on Wednesday.
Have continued with some small POPs Wednesday and Wednesday night
to account for the lift with only weak inhibition to convection. I
expect this front to be south of the area by Thursday, but there
are signs that return flow and elevated storms may try and develop
for Thursday night. Will need to stay tuned to see how things
evolve.

Seasonal temps are anticipated for next week with no strong signal
for a cold or warm anomaly from the models. Look for highs in the
70s and lows generally in the 40s. There could be a slight cool
down on Thursday low level flow is able to remain from the
northwest as progged by the GFS.

&&

.AVIATION...(For the 00Z TAFs through 00Z Friday Evening)
Issued at 705 PM CDT THU MAR 26 2015

Mvfr cigs will overspread the TAFS sites from the north by 03z
with cigs 2000-3000 ft with 4-6 miles in light rain lowering to
1000-1500 feet by 06z with -ra lingering. The mvfr cigs will then
scatter near 2500 feet by 14Z all sites with vfr conditions then thru
the remainder of the TAF forecast. North to northeast winds will
be the rule through the fcsts at 5 to 10 kts.

&&

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

$$

SHORT TERM...Bowen
LONG TERM...Wolters
AVIATION...63






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