Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 111011
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
611 AM EDT Fri Jul 11 2014
...Updated Aviation Discussion...
.SHORT TERM (Now through Saturday)...
Issued at 245 AM EDT Fri July 11 2014
Well...the main story is increasing summertime temps.
Sfc High pressure will slide from Lake Huron and Georgian Bay over
to Lake Ontario and the St Lawrence Seaway later today and over to
Lake Champlain on Saturday. Winds will be light and variable today
in response to sfc ridging (start off NE, then easterly, then all
over the place this afternoon and evening).
Based on yesterday warmer than fcst mercury readings, mainly due to
sfc vegetation drying out and H8 and H9 temps warmer 1-2 degrees,
have brought highs today 88-92 CWA wide with some high level CI with
few higher based cumulus during the afternoon. Sfc dew points will
mix out again into the upper 50s so residents will experience a "dry
Mid and Upper level clouds will be on the increase tonight as
short wave over over Hawkeye State brings MCS cloud debris
southward. Lows will drop down to the 65 to 70 range.
Saturday will be 1-2 degrees warmer, unless mid and upper level
cloud debris persists. H8 temps warm to +18C across the wrn CWA, but
cloud cover may keep temps in the upper 80s. I am still working out
details on the high temps. Agree with HPC on keeping the pcpn axis
on Saturday along I 80 (IN-IL-IA-NE), so took out slight chance pops
across Srn IN (jives with IND/PAH).
The bigger weather story is in the extended fcst!
.LONG TERM (Saturday Night through Thursday)...
Issued at 300 AM EDT Fri Jul 11 2014
A shift in the pattern through the long term will bring a
significant change in the weather from the first to second half of
the forecast period. Aloft the long term will begin with weak
ridging and west to northwesterly flow. A deep trough some two to
three standard deviations below normal will then slowly sink
southeastward into the eastern CONUS through Tuesday before slowly
beginning to lift northeastward through the end of the work week.
The forecast should start out dry on Saturday night. Most of the
forcing will stay well to the north of the area Saturday night
closer to a cold front which will move through early next week. On
Sunday moisture return will continue across the region with
dewpoints rising back into the upper 60s to lower 70s. With
southwesterly flow, very warm air aloft, and dry ground, highs will
rise into the lower to mid 90s on Sunday. We will become unstable in
the afternoon. Though there will not be much of a forcing mechanism,
scattered showers and thunderstorms could develop Sunday afternoon,
particularly across southern IN and north central KY. However, there
is some uncertainty in how much coverage there will be. With the
temperatures and dewpoints as high as they are, heat indices look to
top out in the upper 90s to near 100 during the afternoon.
Better chances for showers and storms will come Sunday night through
Monday night. There is still a possibility of overnight MCS activity
Sunday night which would make predicting precipitation on Monday
difficult. The best chance for storms Monday may be across south
central KY. Whenever storms do develop, they will have the potential
to produce heavy rain as PWAT values rise to near two inches. Gusty
winds will accompany the strongest storms as well.
The aforementioned cold front looks to move through Tuesday morning.
Any ongoing showers and storms should come to an end as the front
moves through and much drier and cooler air moves in behind it.
Temperatures will be much cooler in the wake of this front. Highs on
Wednesday look to top out in the upper 70s, some 10-12 degrees below
normal for this time of year. Thursday will be just a couple of
degrees warmer. Lows will be in the upper 50s to around 60.
.AVIATION (12Z TAF Update)...
Issued at 605 AM EDT Fri Jul 11 2014
Well...VFR fcst with High pressure over the Finger Lakes of Wrn NY
which is keeping light Nly flow. This sfc ridge will create some
light and variable winds as the high slowly moves towards N New
England. Winds will go to NE, then E and SE and SW by nightfall but
all <6 mph.
Storms will fire up late tonight over NE/IA and some of the mid and
high level cloud debris will slide SE around Central Plains ridge
and increase clouds by Sat am at SDF.