Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 110526
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1126 PM CST Tue Jan 10 2017

...AVIATION UPDATE...

.SHORT TERM...(This evening through Wednesday)
Issued at 303 PM CST Tue Jan 10 2017

Temporary subsidence noted at 500 mb exiting into the Midwest region
this afternoon. Meanwhile, two upper shortwave troughs were centered
over Alberta, Canada and the other off the coast of Washington.
Towards the sfc, previous system has dragged through a sfc cold
front, raising west to northwest winds along and just behind the
boundary at 15 to 25 mph sustained. These winds will weaken to
around 10 mph around sunset as an area of weak low pressure develops
over western Kansas after midnight. Northerly winds this evening
back to the southwest in response, increasing by mid morning as the
sfc low deepens ahead of the next cold front. Skies are partly to
mostly cloudy throughout the day on Wednesday with temps starting
out in the lower 30s before quickly rising to the 50s along and
south of Interstate 70. Areas behind the front only reach the lower
40s.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 303 PM CST Tue Jan 10 2017

Thursday through Thursday night, a surface ridge of high pressure
will build southward across eastern KS. The NAM model shows the
potential of some patchy freezing drizzle in the morning, though all
other models keep any light precip northeast and east of the CWA. For
now, I will keep a dry forecast going. Low-level CAA will only
allow highs to reach the mid 20s across along the NE border to
lower 30s south of I-70.

Friday through Sunday, The intense upper level trough digging
southward along the CA coast will move onshore across northwest
Mexico then lift northeast into NM by Sunday evening.

Friday through Friday night, well ahead of the upper trough
southerly 850mb winds will transport deeper gulf moisture north-
northeast across TX into southeast KS. The cold surface ridge will
remain in place and isentropic lift will cause an area of freezing
rain to develop across south central and southeast KS during the
afternoon hours of Friday. The ECMWF shows this area of freezing
rain will move northeast across much of east central KS into
portions on northeast KS. The greatest QPF will be across the
southeast counties with close to 0.25 inches along and southeast of
I-35. Temperatures will be in the lower to mid 20s with the warm
nose of 4 to 5 degree C. Thus, the precipitation will remain in the
form of freezing rain. Lighter amounts will occur along and north of
I-70 with less than 0.1 inch of QPF. The warm nose may be less than
3 degrees across northeast and north central KS, thus some of the
light precip may be in the form of sleet. The GFS is similar to the
ECMWF solution but the QPF is higher with 0.45 inches across the
southeast counties and 0.2 inches along the I-70 corridor. Given
temperatures in the lower to mid 20s, ice will accumulate on roads,
trees and electrical wires will occur through the night and early
morning hours of Saturday.

Saturday, as the upper low moves across northwest Mexico, the 850mb
winds will back across western TX and veer across southern KS and
MO. There may be a break in the freezing rain across the CWA from
the mid morning hours of Saturday through Saturday afternoon as
the better isentropic lift shifts east-southeast of the CWA.
Northeast surface winds will continue the low-level CAA and highs
will only reach the mid to upper 20s. There still may be freezing
drizzle off and on across the CWA through the day.

Saturday night through Sunday, The intense upper trough will lift
northeast into eastern NM by early Sunday evening. 850mb southerly
winds will advect deeper moisture northward back into eastern KS
Saturday night. As the second surge of deeper moisture moves north,
isentropic lift will cause widespread freezing rain to develop
across the CWA. The ECMWF shows the freezing rain developing across
south central and southeast KS Saturday evening then slowly lifting
northward through the night. The ECMWF has nearly 1.8" of QPF across
Anderson county by 18Z SUN and this will be in the form of freezing
rain. This could result in 0.5" of elevated radial ice
accumulations. Areas along and north of I-70 will receive less than a
0.5" of QPF for .10" to .25" of elevated radial ice accumulations.
During the late afternoon hour of Sunday slightly warmer air will
begin to advect northward, the southeast counties of the CWA may
warm into the mid 30s which will end the significant icing. Areas
along and north of I-70 will remain at or slightly below 32 degrees
through the afternoon hours.

Sunday night through Monday, the intense upper low will lift north-
northeast from western NM into western KS. Eventually warm surface
temperatures will advect northward across the eastern two thirds of
the CWA and temperatures will slowly be rising through the mid and
upper 30s. The freezing rain along and north of I-70 will change
over to rain, though temperatures may remain at or below freezing
across north central KS where the freezing rain may continue through
Sunday night into Monday morning. There may be significant icing
across north central KS as nearly 1.5" of QPF will fall from 00Z MON
through 18Z MON. During the late afternoon hours a mid level dry
slot will advect northeast across the CWA ending the precipitation by
Monday evening. Highs Monday afternoon will warm into the mid 30s
across north central KS, with upper 30s to lower 40s across east
central KS.

Tuesday, Looks dry as the upper low tracks north into southwest NE.
Southwesterly surface winds will help to warm Highs into the lower to
mid 40s, which will help to melt any left over ice.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday)
Issued at 1126 PM CST Tue Jan 10 2017

Not a lot of change to the forecast thinking as models continue to
show limited moisture in spite of some dynamic flow over the
forecast area. Therefore a VFR forecast is expected through
tonight and much of Wed. Profilers showing the low level jet is
intensifying so LLWS continues to appear likely with a steep
nocturnal inversion setting up. Models have shown some MVFR CIGS
developing behind the front late Wed and Wed evening with decent
low level cold air advection. With some consistency from the
models, have introduced a BKN MVFR CIG around 00Z Thursday.

&&

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

$$

SHORT TERM...Prieto
LONG TERM...Gargan
AVIATION...Wolters



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