Area Forecast Discussion
Issued by NWS Paducah, KY
FXUS63 KPAH 190845
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
245 AM CST Wed Nov 19 2014
.SHORT TERM...(Today through Friday)
Issued at 245 AM CST WED NOV 19 2014
Main upper level pattern early this morning features a highly
amplified but narrow ridge along the west coast and a large trough
east of the Rockies. Sfc map indicates high pressure centered along
the Gulf Coast states and a frontal boundary to our northwest. The
pressure gradient should continue to tighten as this clipper type
system sags southeast toward the area, so winds should pick up.
Temperatures have already bottomed out and started to climb over the
last few hours in response to the southerly winds starting.
The front should bring some clouds to the region as it passes
through this afternoon. Some warmer air will advect into the area
ahead of this front and our afternoon highs should get into 40s.
Looking upstream, already in the 30s/40s to our west and models are
not handling that well attm except for maybe the HRRR/RUC. Temperatures
will be tricky dealing with how much warm air returns before clouds
High pressure builds in tonight and into Thursday providing dry
weather. The degree of cold air behind this clipper system does not
appear to be nearly as significant as previous systems, but we will
still see a 5 degree or so drop in highs for Thursday.
Models continue to toy around with the idea of some possible
precipitation creeping into our far southern MO counties btwn
06Z-12Z Friday ahead of a developing warm front to our south. It
seems as though models have backed off on the timing of the return
moisture. What is not as certain is what the sfc temperatures will
be if any precipitation does arrive. Too close a call to change the
forecast in one direction or the other, so light freezing rain/light
rain chances will remain.
During the day on Friday, we should be seeing a pattern change take
place as the huge chunk of cold air over the Great Lakes and down
into our area, starts to head east. We will see upper heights rising
throughout the day, as low level moisture deepens significantly.
Really think that by the time any precipitation develops,
temperatures will be above freezing. But in case precipitation
begins to fall btwn 12Z-15Z, will have to maintain that chance for
freezing rain since there are indications that temperatures could be
around freezing. Chances for rain overspreads most of the area
during the afternoon hours on Friday.
.LONG TERM...(Friday night through Tuesday)
Issued at 245 AM CST WED NOV 19 2014
At the beginning of the period, a split flow regime will be in
place across the CONUS, with a strong southern stream system along
the AZ/Mexico border. At the surface, strong high pressure will
reside over the eastern U.S. with broad return flow into the
nation`s mid section.
Weak s/wv energy should spark some rain/shower activity Friday
night into Saturday. Tried to keep best PoPs over the W/NW part of
the region, lower SE. Meanwhile, the southern stream upper system
should move from west TX 18z Sat, to the Red River Valley region
06z Sunday. A cluster of models continues to favor a slightly
slower solution with this system, and this makes sense in this
split flow regime. It should not begin acceleration until it
becomes more consolidated/phased with the northern branch Sunday.
Therefore, we have more resolution in the forecast for Saturday
night. Think chances Saturday evening through midnight will be
lower. But from Midnight-6 a.m. Sunday, showers and a few
thunderstorms will rapidly spread from SW to NE across the area.
We continue with categorical PoPs, but after midnight. Sunday
morning, band should be over NE sections of the CWFA. However,
there is a good chance of lingering convection even through the
rest of the day given the unsettled SW flow aloft and frontal
boundary in the vicinity.
A band of convection is forecast across the area Sunday night as
well. By then...we will have more of a longwave trof pattern
established with energy passing across the area within the trof.
Elevated instability persists in both the ECMWF and GFS, mainly
southern sections even into Sunday night, so maintained some
thunder. The chance of showers should decrease from SW to NE
Monday with dry weather Monday night through Tuesday.
Continued to use a blend of MOS and base model output for temps.
After some 50s Saturday and 60s Sunday, will cool back down early
next week. However, nothing as cold as what we have experienced
Issued at 509 PM CST TUE NOV 18 2014
Mid and High cover will be on the increase in the latter half of
the TAF period...with cigs lowering but staying VFR during the
late morning-pm hours. Winds will become gusty southwest as the
front approaches, and shift to west/northwest as the front makes
its passage toward the effective end valid time.