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Area forecast discussion
National Weather Service Topeka Kansas
541 PM CST Fri Nov 22 2019

..update to aviation forecast discussion...

Short term...(this evening through saturday)
issued at 312 PM CST Fri Nov 22 2019

A complicated upper air pattern remains in place at this hour across
the Continental U.S.. a trough with associated frontal system at the surface
continues to move through the New England region. The Central
Plains is dealing with an upper low that had deepened earlier in the
day as it continues to translate east out of the central rockies --
more about this to follow. The western Continental U.S. Has a few upper level
minor circulations along the coastal areas. Sub-tropical jet stream
is is making its presence on WV imagery along the Gulf coastal
region with the modified southern branch of the polar jet and
associated cyclonic flow over the Southern Plains region.

Near the surface over the local area, a band of heavy to moderate
snow as been continuing to erode as it lifts north over the area.
The band of now light to moderate snow remains over the Hwy 36
corridor. Have canceled the previously issued Winter Weather
Advisory for portions of north central Kansas. This area generally
saw 1-2 inches of snowfall with a few higher amounts locally as some
convective elements were maintained for a period of time within the
band early on with some pockets of negative epv and more intense
ageostrophic circulations within the overall 700-600mb mid level
frontogenetical band. Much drier air has been maintained to the
north of the area, so the rest of the snow band should continue to
erode much more quickly into the latter portions of the afternoon as
it moves into Nebraska. Only expecting some areas of light snow
over northern zones to flurries points further south to the I-70
corridor for the next few hours. Expecting low stratus to be
maintained for much of the evening and overnight hours with enough
wrap around moisture continuing to impact the area as the upper low
slowly lifts to the east and northeast of the area by early Saturday
morning.

Saturday and the rest of the short-term forecast period look to
remain dry. Thinking cloud cover clears the area too late tonight
for efficient enough radiational cooling to take place. Therefore,
have not gone with an fog mention at this time. Perhaps if clearing
can take place and winds calm enough with any localized decoupling
then fog may set up over primarily western areas that have seen
snowfall. Have maintained highs only in the 40s for Saturday as
weak ridging aloft works over the area and mostly a northwest flow
component is in place. With snow still on the ground over
northwestern areas of the forecast area, then could see some cooler
air advected back over the area. This would likely counter any
insolation with the lower overall solar angle anyway. Saturday
night also remain very chilly with light west to northwest breeze
behind a weak surface trough moving through late Saturday -- looking
for lows to fall into the upper 20s.

Long term...(saturday night through friday)
issued at 312 PM CST Fri Nov 22 2019

Conditions will remain quiet heading into Sunday as flow turns
westerly, which will result in warm air advection bringing temperatures to the mid
to upper 50s under mainly sunny skies. Above average temps will
continue through the overnight hours with lows in the 30s area-wide
by Monday morning.

A shortwave trough will develop in the western US on Monday with
surface low pressure ahead of this feature in the southern rockies.
There are hints in the models for winds to shift northwest during
the afternoon with a weak frontal boundary, but this appears to have
little or no effect as temperatures still reach the mid to upper 50s
and dry weather is expected. The main front associated with this
system should arrive Tuesday as the trough passes through the
Central Plains. Plenty of details with this system are still in
question as the European model (ecmwf) deepens the trough more than the GFS, and the
GFS has shifted the track of the low further northwest again
compared to yesterday's runs, while the European model (ecmwf) tracks it slightly
further west than the GFS. This has resulted in the better precip
chances shifting back toward northern Kansas into NE, where lift is
maximized in the base of the trough. Rain looks most likely for a
majority of the County Warning Area during the day Tuesday with temps ranging in the
40s and 50s, but some rain/snow could mix in early in the morning
for places closer to the NE border, especially given the proximity
of the 540 thickness line for 1000-500mb. That being said, however,
the timing of the cold front as well as the system track will both
likely have a considerable impact on temperatures and ultimately p-
type in all locations. The European model (ecmwf) solution drags the system behind a
bit longer into the evening, so any lingering rain could transition
back to snow as well.

Given the uncertainty in play for the Tuesday system, confidence is
even lower in the forecast beyond that as that pattern will have a
lasting impact on what comes after. For now, we do look to dry out
for Wednesday as weak ridging comes in place, but only briefly.
Weaker waves ahead of a large trough off the California coast combined with
return flow could result in small precip chances on Thursday and
Friday. But again, many variables such as temperature and p-type
will be dependent on the synoptic pattern and overall environment
left behind after Tuesday.

&&

Aviation...(for the 00z tafs through 00z Saturday evening)
issued at 541 PM CST Fri Nov 22 2019

VFR and MVFR cigs will be prevalent through 12z, but low MVFR to
IFR cigs are possible in the mhk terminal through 14z. Forecast
sounding show cigs improving to VFR in the 15z to 18z time period
at all locations. Winds light north becoming variable then light
west under 10 kts after 14z.

&&

Top watches/warnings/advisories...
none.
&&

$$

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