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Area forecast discussion 
National Weather Service Topeka Kansas
539 PM CDT Tue Oct 21 2014

..aviation update...

Short term...(this evening through wednesday)
issued at 245 PM CDT Tuesday Oct 21 2014

At 3 PM this afternoon, water vapor imagery showed much of the
plains region underneath upper ridging while the shortwave trough
was deepening across Idaho into southern Montana. Gusty southerly
winds at the surface were observed advecting moisture into central
Kansas as dewpoint temperatures were increasing to near 60 degrees.
Across northeast Kansas, highs were a tad cooler in the middle 70s
while influence from the sfc ridge to our east kept surface air
drier with dewpoints dropping into the lower 40s.

Surface trough deepens over eastern Colorado this evening inducing an
h85 low level jet to increase around 30 kts. Moisture advects
northeastward into the County Warning Area as dewpoints rise into the 50s
overnight. Mixing between h85 and the surface also increases to
near 10 kts over north central areas where low level stratus
appears more likely as opposed to fog. Weak isentropic lift at the
300k surface seen from the NAM and 4-km WRF models show
development of isolated activity over far eastern Kansas just before
sunrise. With forcing being particularly weak and saturation being
brief in the morning, decided to mention a few sprinkles being
possible. Otherwise focus turns to the incoming trough Wednesday
afternoon with slight chances of precip mentioned after 18z.
Timing between short term and mid term guidance shows the optimal
lift arriving in north central areas near 00z, however could not
rule out scattered showers during the afternoon. Elevated
instability seen in only a few hundred j/kg may result in isolated
thunderstorms.

Long term...(wednesday night through tuesday)
issued at 245 PM CDT Tuesday Oct 21 2014

Upper trough continues to move across the forecast area in the early
morning hours on Thursday. Lapse rates and cape remain rather weak,
and progressive nature keeps chances for heavy rainfall on the low
side. Have precipitation clearing the area by noon, but could be a
few hours faster. This keeps overnight lows in the 50s, and highs
still manage to make it back into the lower 70s after the trough
passes.

In terms of sensible weather, Friday through Sunday continue to
bring above normal temperatures with highs in the upper 70s near
80 each day and lows in the 50s. Winds initially vary a bit as low
pressure passes to our north, but come around out of the south by
late Saturday and increase on Sunday afternoon. Flow aloft makes a
shift from a passing upper ridge to an approaching trough with SW
flow over the state.

Timing of the next upper trough still in question, although both GFS
and latest ec bring the next front through on Monday afternoon. Ec
had split the energy into northern and southern tracks but now
seems to be coming toward a single more progressive single wave.
Kept lower end rain chances on Monday, which could continue into
Tuesday if system slows a bit as ec suggests. May be cooler across
the northwest counties on Monday as trough comes in and cooler on Tuesday
behind the system.

&&

Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 539 PM CDT Tuesday Oct 21 2014

Models continue to show some moisture advection and isentropic
lift between 900mb and 850mb after 06z. Only the NAM forecast
soundings suggest there is any instability with the rap and GFS
maintaining some inhibition above this layer. Therefore will
maintain a dry forecast for the terminals overnight and monitor
trends. Larger scale forcing does not affect the area tomorrow
until after 00z, so the forecast has VFR conditions persisting.

&&

Top watches/warnings/advisories...none.

&&

$$

Short term...Bowen
long term...67
aviation...wolters

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