Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
FXUS63 KDVN 160016 CCA
Area Forecast Discussion...corrected aviation
National Weather Service Quad Cities IA IL
553 PM CST Wed Feb 15 2017
...00z AVIATION UPDATE...
Issued at 320 PM CST Wed Feb 15 2017
Deep upper level trough was located across the Great Lakes region
keeping the low stratus across lower MI and into the upper OH
valley, under the cyclonic flow. Back at the ranch, in the dvn
cwa, only patchy wisps of cirrus were noted on satellite and
looking out the window.
As expected today is the coolest day of the week with 3 pm
temperatures in the mid 30s to mid 40s.
.SHORT TERM...(This Evening through Thursday)
ISSUED AT 320 PM CST Wed Feb 15 2017
Forecast focus on mild temperatures on Thursday.
Tonight: Other than areas of mainly thin cirrus, mostly clear to
fair skies can be expected. This along with a very dry airmass and
light to calm winds will allow temperatures to drop to the chilly
levels, due to a weak ridge of high pressure over the area. Lows
should range from the lower to mid 20s north to around 30 in our
far southern cwa.
Thursday: This day begins a spectacular warm-up which will
continue well into the long term (see that discussion below). The
deep storm system in the northeast United States begins to lift
northeast while an intense storm system slams the West Coast.
This allows heights to dramatically rise in the Plains and
southerly winds to return to the cwa. Plenty of sunshine and dry
ground will push temperatures above any guidance, as we have seen
the past several days. Afternoon highs should range from the mid
40s at Freeport, IL to the lower 60s at Memphis, MO.
.LONG TERM...(Thursday Night through Wednesday)
ISSUED AT 320 PM CST Wed Feb 15 2017
The main forecast concern for this period will be temperatures
throughout and next weeks storm system. Models are in good overall
agreement with the Canadian being an outlier in moving out the storm
system for early next week.
A progressive 500 hpa flow is forecast by all models across the
northern CONUS with a pair of shortwaves cutting off low in the
southern stream across the southwestern US moving and slowly
eastward. There will be periods of a more amplified pattern ahead of
the two separate cutoff lows as strong ridging builds northward
Friday and again Sunday into Monday. Temperatures will remain well
above normal through the period with slightly cooler temperatures
Tuesday and Wednesday.
An amplified but progressive 500 hpa ridge will lead to temperatures
above normal on Friday. Forecast BUFR soundings through the period
show the potential to mix to between 950 and 925 mb on Friday but
unable to tap into the +12 to +14C air at 850. This may lead to high
temperatures in the vicinity of records on Friday. Southwesterly
winds near 20 knots have the potential to mix to the surface on
Friday so expect a breezy day. Temperatures will be slightly cooler
Saturday and Sunday as winds shifts to the northwest and some
relatively cooler air moves into the region. Temperatures will
remain well above the normal though despite the cooler air moving
through the region.
Warmer air will again surge northward on Monday ahead of the opening
wave in the southern stream while a second northern stream wave
moves across the region. Forecast soundings show stronger southwest
winds and slightly deeper mixing on Monday but cloud cover and
precipitation may limit the high temperature potential that day. The
GFS and Canadian show phasing between the northern and southern
stream shortwaves and thus more moisture to work with than the ECMWF.
This will play a big role in precipitation chances and amounts
for next week. Models also do produce some CAPE monday afternoon
into Monday night but soundings show steeper lapse rates which
would prohibit convection so will leave thunder out of the
forecast for now.
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
ISSUED AT 549 PM CST Wed Feb 15 2017
Vfr conditions will persist through the TAF cycle. NW winds around
10 kts will become light and variable by mid evening as high
pressure ridge builds in. Thursday morning winds will increase from
the SE at 10-15 kts, then the winds will begin to veer to SW during
the afternoon as a warm front lifts through.