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Area forecast discussion
National Weather Service Quad Cities Iowa Illinois
1046 PM CST Thu Dec 5 2019

..aviation update...

issued at 250 PM CST Thu Dec 5 2019

Sunny and mild conditions were found across the area this afternoon.
2 PM temperatures were in a range from the mid to upper 40s
northeast, to the upper 50s and around 60 in the southwest. The
warm air was being being drawn into the area by a south to
southwest low level flow ahead of a weak low pressure center over
southern Minnesota and trough axis reaching across northwest Iowa into
central Kansas. A trailing cold front across southeast South Dakota into eastern NE
will push through the local area tonight, bringing much cooler
weather for Friday.


Short term...(this evening through friday)
issued at 250 PM CST Thu Dec 5 2019

The colder airmass and increasing cloud cover moving into the area
overnight will result in friday's temperatures topping out 10 to
nearly 20 degrees lower than today. Current timing has this front
pushing through roughly between midnight and 4 am, marked by gusty
northwest winds and possibly a period of low clouds. Precipitation
is not expected as there will be little upper level forcing or
moisture to work with in the split flow regime. Low temperatures
will occur around sunrise, from the mid 20s north to lower 30s in
the far south.

Friday: any Post frontal low clouds will likely dissipate from
northwest to southeast through the day as the increasingly
anticyclonic low level flow breaks up the clouds trapped in the low
level inversion. Modest cold air advection on northerly winds will
hold highs to the 30s to near 40.

Long term...(friday night through thursday)
issued at 250 PM CST Thu Dec 5 2019

After a return to above normal temperatures this weekend, much
colder and well below normal temperatures will be the main story
going into next week. The pattern remains mainly dry, outside a
period of possible rain or snow with a system that will affect the
region from late Sunday night through Monday night.

This change to colder weather will be the result of a developing
long wave upper level trough carving out over the central U.S.
Monday and Tuesday. Ahead of this, a northwest to zonal upper level
flow will be in place with a southerly low level return flow
Saturday and Sunday. After overnight lows in the 20s, saturday[s
highs should return to the 40s, then 40s to lower 50s Sunday.

Models are beginning to converge on the idea of a wave of low
pressure at the surface developing over the Southern Plains Sunday
night, tracking northeast into the Great Lakes by Monday night as
the upper energy phases into the long wave trough. Just how much
moisture and forcing wraps around and affects the forecast area is
still questionable, but most models do have at least light quantitative precipitation forecast over
forecast area from Sunday night into Monday night and slight to low
chance pops for snow, or possible rain/snow are maintained.

The greater certainty is that there will be brisk winds and an
infiltration of much colder, modified Arctic air that follows
this system for late Monday and especially Tuesday. Thus forecast
highs in the 30s for Monday are low confidence, but Tuesday looks
more certainly limited to highs in the teens and 20s, followed by
overnight lows in the single digits or colder if there is snow
cover. Dry weather is expected for Wed and Thu with moderating
temperatures, but still holding well below normal with highs in
the 20s and lows in the single digits and teens.


Aviation...(for the 06z tafs through 06z Friday night)
issued at 1044 PM CST Thu Dec 5 2019

MVFR cigs will spread across the area in the next 6 hours. Gusty
northely winds are expected tomorrow. There is a question of when
do the MVFR decks break up. Currently extended them into early


Dvn watches/warnings/advisories...


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