Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 202101
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
301 PM CST Fri Jan 20 2017

.SHORT TERM...(This evening through Saturday)
Issued at 300 PM CST Fri Jan 20 2017

20Z water vapor imagery shows a closed upper low over western KS
with a surface low over the OK panhandle. Easterly low level flow
on the northeast side of the low pressure system has keep low
ceilings and fog a little longer into the day. But southerly
surface winds are starting to spread north through east central KS
and allowing conditions to gradually improve.

For tonight and Saturday, low clouds are expected to persist
through the night. Once the low pressure system passes to the
north, models show low level moisture wrapping back into northern
KS. So think there could be some stratus over parts of the area
through late morning Saturday. Precip chances should increase
through the early evening over north central KS as the upper low
moves into central NEB. Once the low passes, the forcing for
precip will diminish along with the precip chances. Models also
indicate that chances for dense fog to redevelop will be mainly
along the NEB state line. Although there are indications of some
weak dry air advection developing overnight as winds shift to the
west and southwest. So confidence in widespread dense fog is not
high enough for another advisory. The exception would be if the
stratus were to scour out, some radiational fog would not be out
of the question. This will be something for later shifts to pay
attention to. Lows tonight are expected to be in the 30s, or
slightly warmer than the previous forecast thinking the low clouds
would hold in for the most part. For highs Saturday, forecast
soundings mix the boundary layer to at least 900MB. Think with
some sunshine by the afternoon that temps could warm into the mid
and upper 50s. This is in line with what the previous forecast
had.

.LONG TERM...(Saturday night through Friday)
Issued at 300 PM CST Fri Jan 20 2017

Relatively quiet weather is expected for much of the period
across NE Kansas with continued above average temperatures through
Tuesday and then a return to seasonal temperatures for the middle
to latter part of the week. The best chance for any precipitation
will be Tuesday into Wednesday.

The second of two lows embedded in a longwave trough will track
through Oklahoma during the overnight hours on Saturday into
Sunday. A 15 to 25 kt NE flow between 700 and 900 mb should
help erode the wrap-around rain along the northern periphery of
the low near the southern border of the CWA. However, both the
12Z NAM and EC have started hinting at some light precip
overspreading the area overnight and have started to raise POPs
slightly to account for this uncertainty. Only weak CAA will
follow in the wake of this system before surface ridging passes
through Monday morning and southerly flow streams back across the
area.

A strong 160 kt jet will migrate eastward across the western
CONUS on Monday with lee cyclogenesis taking place along the Front
Range early Tuesday morning along the right rear quadrant of this
jet streak. There remains some discrepancy in the track of this
deepening low, but guidance solutions are converging on a course
that will take the low across or just north of the CWA, keeping
the bulk of the associated precipitation north of the area.
Despite this dynamic system, there will be limited moisture out
ahead of this low owing to a dry southwesterly mid and low-level
flow originating from the SW CONUS. A dry slot should work its way
northeastward along the east flank of the upper low during the day
on Tuesday and likewise bring an end to any precip in the WAA wing
of the cyclone over northeast KS. This storm will usher in a cold
Canadian airmass in its wake with H850 temps falling 15 to 20 C to
around -10 C by Wednesday night. This will drop temperatures back
to near normal for this time of year. Any precip on the backside
of the low on Tuesday night and Wednesday will likely fall as a
rain/snow mixture, but any amounts will hinge on the exact track
of the low.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday)
Issued at 1122 AM CST Fri Jan 20 2017

While the surface low remains to the south and west of the
forecast area, think easterly low level winds will allow IFR and
LIFR to persist. Main question is whether there will be a period
of improvement late this afternoon before wrap around moisture
moves in overnight as the low pressure system lifts northeast. In
general thing weather conditions will remain restrictive until
late morning Saturday when low level moisture is able to mix out.


&&

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

$$

SHORT TERM...Wolters
LONG TERM...Skow
AVIATION...Wolters



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