Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 031905
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
305 PM EDT Sun May 3 2015
.SHORT TERM (Now through Monday Night)...
Issued at 251 PM EDT Sun May 3 2015
The synoptic pattern this afternoon features generally weak zonal
flow aloft, which will slowly amplify through the short term
period. This regime will bring seasonably warm temperatures and
continued dry conditions to the Ohio Valley.
For tonight, we will continue to see a few passing mid/high clouds.
Southwest winds will slacken overnight, once again allowing for some
patchy fog to develop in some isolated, fog prone locations.
Overnight lows will be in the low to mid 50s.
For tomorrow, expect more of the same with partly cloudy skies and
southwesterly surface winds continuing. A surface front will slide
into northern IL/IN during the day. This front and associated
precipitation should stay to the north of the region, but can`t
completely rule out a rogue shower across southern IN tomorrow.
This threat appears very low, so will continue with a dry forecast.
Much of the convective debris should remain to the north of the
region, thus the sunshine coupled with 850mb temperatures about one
degree warmer than today and good southwesterly surface flow should
yield highs in the low to mid 80s. Overnight lows tomorrow night
will drop into the upper 50s and lower 60s.
.LONG TERM (Tuesday through Sunday)...
Issued at 303 PM EDT Sun May 3 2015
Overall pattern being forecasted by the guidance has not changed
significantly in the last few days. A highly amplified upper level
pattern characterized by a trough in the western US with a ridge
across the east is forecast to persist throughout much of the long
term period. The global models are still suggesting that some sort
of tropical system will develop off the SE US coast and the
development of a Rex block still looks likely from mid-late week.
Thus, this should keep the overall trough west, ridge east pattern
going as we head into next weekend.
With the trough out to the west, we`ll see a continued broad
southwesterly flow continue across much of the Ohio Valley. Main
moisture plume still looks to remain out to our west while we remain
near the upper ridge axis. Thus, overall precipitation chances look
to be below climatology through the period. Based on the latest
data, we feel that most, if not all of next will remain generally
rain free. Temperatures will gradually moderate through the
period. The beginning of the period will see temperatures in the
upper 70s to the lower 80s with readings generally warming into the
81-86 degree range for the remainder of the week. Overnight low
temperatures will generally cool into the upper 50s to around 60.
Stuck close to an ECMWF/GEM compromise on raw temps here based on
recent verification stats.
Toward the end of the period, it still appears the pattern will
break down and the upper trough will eventually head eastward. Much
of this forecast will depend on the evolution of the upper low
expected to be in the southwest Atlantic. Should the blocking
pattern aloft hold a little longer, the overall breakdown of the
pattern may end up being delayed by a few days into early next
week. For now, have cut back on PoPs and kept them in the isolated
range for Sat/Sun.
.AVIATION (18Z TAF Update)...
Updated at 1249 PM EDT Sun May 3 2015
VFR conditions will persist at the TAF sites today. Scattered/broken
high clouds will continue to stream over the region and winds will
remain out of S/SW. Another night of light winds and mostly clear
skies could result in light, shallow fog again at BWG during the
pre-dawn hours Monday. Otherwise, Monday will be similar today
with WSW winds and just some passing mid/high clouds.