Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 171114
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
514 AM CST Mon Nov 17 2014

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 301 AM CST MON NOV 17 2014

700 MB temperatures between 16 and 28 below zero were surging
southward this morning as an amplified longwave trough was
rotating southeast across the central and eastern CONUS. Across
northeast Kansas, the surface cold front was stretched from
southern Kansas, pivoting northeast over the Midwest. The actual
colder airmass lagged behind the boundary over southern Nebraska
where northwest winds were gusty with some scattered to broken
stratus. Meanwhile lows this morning will hover in the teens
before the CAA increases later this morning.

Cloud cover increases, especially over northeast and east central
areas later this morning into the afternoon as the weak embedded
vorticity maxima within the mean flow slide southeast. Forecast
soundings depict weak areas of lift in the ice growth layer
coinciding with shallow saturation within a 3 to 4 KFT layer.
Forcing is weak/saturation is limited and will therefore maintain
mention of scattered flurries mid morning through afternoon over
north central, far northeast, and east central locations. Strong
mixing through the column with northwest winds gusting to near 30
mph will create a very cold and blustery afternoon. Record cold
highs are likely as MOS and short term guidance are persistent in
the upper teens to lower 20s. For detailed information, please refer
to the Climate section below.

The wave exits this evening as high pressure builds into the region.
Winds become light from the west between 5 and 10 mph. Near record
lows are forecast as temps dive into the single digits. Between
midnight and 6 AM, wind chills range from 2 above to 10 degrees
below zero.

.LONG TERM...(Tuesday through Sunday)
Issued at 301 AM CST MON NOV 17 2014

The forecast for Tuesday through Friday remains dry. Initially
northwest flow persists and a shortwave with reasonable forcing
is progged to move through the area Tuesday night. However very
dry air in place when the wave passes is a limiting factor and
precip chances remain less than 10 percent. As the week
progresses, the longwave upper trough with the arctic air
eventually moves east and north allowing warmer air and temps to
return with readings a little closer to normal for mid November
by the end of the week. Therefore the forecast has a warming
trend through the week. A cold front should accompany the
shortwave Tuesday night shifting the winds to the northwest for
Wednesday. However cold air advection behind this front is not nearly
as strong with the arctic airmass over the great lakes region and
mid level ridging over the northern Rockies. So with some
insolation and a downslope component to the winds, highs should
warm above freezing.

There remains a fair amount of uncertainty by this weekend as
models show poor consistency with the synoptic pattern change
from a cold upper trough over much of the country to a more
progressive split flow pattern. There appears to be a couple waves
that should move through the southern stream late in the week and
over the weekend. The first is expected to remain south of the
forecast area on Thursday and Thursday night. But the 00Z ECMWF
and GFS bring a more amplified wave into the plains Saturday and
Saturday night. This wave is progged to cause cyclogenesis and
lift a surface low up through MO. Again there is poor consistency
in the models consistency, so with timing and strength differences
in the solutions its hard to be confident in the specifics. The
general trend has been for a chance of precip Saturday and
Saturday night as there has been some signal of forcing. And the
thermal fields have generally been warm enough for any precip to
fall as rain. So have not changed the forecast much from previous
version, and am a little hesitant to lower or remove POPs on
Sunday based on the 00Z runs until the solutions begin to show
better consistency. Specifically I`d like to see better
consistency from the ECMWF which has shown a different variation
of the surface wave each of the past several runs. Therefore the
forecast for the weekend is a compromise with low chances for
precip and relatively mild temps.

&&

.AVIATION...(For the 12Z TAFs through 12Z Tuesday Morning)
Issued at 505 AM CST MON NOV 17 2014

VFR conditions expected at terminals. While moisture is shallow
behind the passing cold front, could see a period of broke low end VFR
stratus track southeast between 18Z and 00Z. At the same time,
west northwest winds increase at or above 13 kts sustained with
gusts in excess of 25 kts. Low confidence remains on scattered
flurries after 18Z and will not include. Gradient wanes overnight
as high pressure settles in and winds weaken to around 5 kts.

&&

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

$$

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






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