Area Forecast Discussion
Issued by NWS Topeka, KS

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000
FXUS63 KTOP 182059
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
359 PM CDT Mon May 18 2015

.SHORT TERM...(This Evening through Tuesday)
Issued at 354 PM CDT MON MAY 18 2015

Gusty northerly winds continue across the CWA this afternoon as the
upper shortwave trough over the Great Lakes migrates eastward this
evening. Mid level zonal flow continues over the central plains, in
between systems as the next closed low rotates over California. Cool
air advecting into northern Kansas is keeping highs a tad cooler
compared to much of the area near 60 degrees this afternoon.

Only notable change may be an increase in high clouds this evening
as winds become light and morning lows drop to the 40s. For
tomorrow, the open wave trough is progged to pivot the Four Corners
region before lifting northeast towards the plains in the evening.
As precipitation develops over western Kansas during the day, clouds
increase west to east over the CWA. Short term guidance depicts a
decent ridge axis of drier air in the lowest 850 mb towards the
surface. There is a chance that light, scattered showers may impact
far north central KS during the afternoon, however believe the best
chances for the area will arrive in the evening as the upper level
forcing arrives. Highs are fairly cooler tomorrow with the denser
clouds arriving by mid afternoon. Average highs range from the upper
50s to lower 60s.

.LONG TERM...(Tuesday Night through Monday)
Issued at 354 PM CDT MON MAY 18 2015

Next round of rainfall on its way overnight Tuesday night into
Wednesday morning as isentropic lift sets up over the warm front
across our area.  LLJ is generally 25-30kts and veers with time,
with the NAM then following with the shortwave trof moving over the
front through the morning.  Second boost of lift from the wave would
increase rain chances a bit later than typical for this setup, but
would also likely end it quickly as wave moves east and subsidence
sets in behind. PW values generally about 1.25 inches in the layer,
which is above normal but not extraordinarily so.  Also some
differences in exactly where larger precipitation bullseye sets up,
with GFS/NAM more along and north of I70, while the EC is farther
south.  Given antecedent ground conditions, and values of PW at this
time, will hold off on a watch until QPF area of best probability is
a little better refined.  All that said, its a cool rainy morning
with highs in the afternoon possibly reaching the upper 50s, then
falling back down into the 40s the following night. Northerly high
pressure moves in for Thursday and better sunshine should bring
highs into the middle 60s.

Friday and into Memorial Day weekend remains a challenging forecast
period.  The upper level pattern looks to still be in flux as weak
ridging will quickly progress off to the East through the day Friday.
Meanwhile, the longer wave trough sets up over the Western CONUS
into the Desert Southwest and digs slightly through the Saturday
night time frame.  A few shortwave troughs do appear to be ejected
from the Central Rockies around this overall larger flow.  This will
bring small chances of mostly rain for Friday night over central and
southeastern KS but also work into parts of northeastern KS.  Return
flow will try to get better organized as weak forcing tries to develop
some frontogenesis and a low pressure area over Western KS.  This
will come into play more Saturday afternoon and evening.  Some
sunshine through the day will likely help set up the best
instability during this time frame as northeastern KS is in the warm
sector.  Exactly how much instability does vary by longer term model
solutions as the GFS still attempts to develop the best southerly
flow while the EC never develops really strong advection into the
region.  Sunday afternoon could be another round of afternoon
thunderstorms as the trough begins to move out of the Southern and
Central Rockies and finally begins develop the surface low over the
Central Plains and Mid Mississippi Valley.  Overnight Sunday into
Monday, this low should lift into the Great Lakes Region while a
cold boundary slowly pushes through northeastern KS effectively
ending precipitation chances through the day Monday.  The entire
period doesn`t look like a washout, but with most time spend in the
warm sector, southerly flow setup from the Gulf of Mexico and just
enough upper level forcing to hold onto the surface low and
associated boundaries, it will take a bit more time to effectively
resolve any definitive times and locations for precipitation and/or
thunderstorm development. Temps should generally be in the 70s for
highs and lows in the 50s.

&&

.AVIATION...(For the 18Z TAFs through 18Z Tuesday Afternoon)
Issued at 1227 PM CDT MON MAY 18 2015

VFR conditions are expected throughout the entire period.  Gusty
winds will die down by 22Z as high pressure continues to move into
the area.


&&

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

$$

SHORT TERM...Bowen
LONG TERM...67/Drake
AVIATION...Heller





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