Area Forecast Discussion
Issued by NWS Topeka, KS

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000
FXUS63 KTOP 030446
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1146 PM CDT Thu Apr 2 2020

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Friday)
Issued at 357 PM CDT Thu Apr 2 2020

A strong cold front was tracking southeastward across the CWA today,
with the front slowly shifting east of the area by late this
evening. An expansive area of Canadian high pressure was diving
southward into the Northern and Central Plains behind this front,
with the modest pressure gradient resulting in strong CAA as
temperatures ranged from the low 70s in far east central KS to the
mid/upper 30s in north central KS by mid-afternoon.  Scattered
precipitation is expected to develop and increase in coverage across
the CWA this evening through the overnight hours and into Friday
morning. The primary concern is with precipitation type as
NAM/HRRR/RAP show strong CAA persisting overnight with low
temperatures plunging into the mid/upper 20s in north central KS and
into the mid/upper 30s across east central KS. While mid-level lapse
rates aren`t that steep, 100-200 J/kg of CAPE will be enough to
result in a chance for some isolated thunder, primarily across
northeast/east central KS. Model soundings show little to no
saturation in the dendritic growth zone, with a saturated warm nose
aloft and a sharp drop in temperatures for a strong saturated low-
level cold nose. As a result, areas of freezing rain will be likely
across much of north central into northeast KS (with some
uncertainty in just how far east the freezing rain potential will
expand).  Models have been trending further east with freezing rain
chances and, as a result, have expanded the Winter Weather Advisory
eastward, with ice accumulations of up to 0.1" possible. Depending
upon how deep the refreeze cold-air layer is, there is a chance for
perhaps more sleet than freezing rain at times, so will need to
monitor this potential closely this evening/overnight. Pavement
temperatures earlier today were still reading in the upper 50s/low
60s, so anticipate that the primary impacts will be for slick spots
to develop on elevated surfaces. Precipitation will gradually shift
further east on Friday with scattered rain showers expected across
eastern KS. Temperatures will not moderate much through the day with
highs only reaching into low/mid 40s.

.LONG TERM...(Friday night through Thursday)
Issued at 357 PM CDT Thu Apr 2 2020

By Friday night, the mid-level trough axis will pivot northeast over
the area with surface high pressure advancing into the area behind
the exiting storm system. The combination of clearing skies and
northerly winds will support low temperatures plunging into the mid
20s to low 30s by Saturday morning.  As the growing season is
starting to extend into east central KS, may need to assess concerns
for frost/freeze conditions across portions of the CWA. Surface high
pressure will remain over the area through the weekend, resulting in
dry conditions and temperatures gradually moderating with highs in
the 50s on Saturday and into the 60s by Sunday.

By Sunday night into Monday, a frontal boundary will extend eastward
along the KS/NE border from a low over eastern Colorado. This front
combined with a couple of weak passing embedded shortwaves may
provide enough forcing to produce some scattered showers and
thunderstorms Sunday night into Monday night. Otherwise, dry
conditions are expected into mid-week as surface high pressure
shifts into the area.  Steady southerly flow will support nice WAA
through the early half of next week with highs into the mid 70s on
Monday and into the 80s by Tuesday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1141 PM CDT Thu Apr 2 2020

Low end MVFR to IFR stratus lingers through Friday afternoon at
all terminals with occasional showers expected until at least 18Z
as the system gradually exits eastward. Confidence is high at
KMHK for a mix of light freezing drizzle and sleet overnight while
the freezing line appears to hover just west of KTOP/KFOE based on
latest forecast soundings. Northerly winds remain above 10 kts
sustained as cigs gradually improve to VFR west to east during the
afternoon.

&&


.TOP WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 10 AM CDT Friday for KSZ008-009-
020-034.

Winter Weather Advisory until 10 AM CDT Friday for KSZ010-011-
021>023-035>037.

&&

$$

SHORT TERM...Hennecke
LONG TERM...Hennecke
AVIATION...22


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