FXUS64 KMEG 251115
Area Forecast Discussion
National Weather Service Memphis TN
615 AM CDT Sat Mar 25 2017
.DISCUSSION... /issued 528 AM CDT Sat Mar 25 2017/
Remnants of a squall line were lifting through west TN early this
morning while a few active bowing segments remained over north
MS. This convection lifted into the Midsouth earlier this morning,
ahead of an upper low centered over eastern OK. This upper low
will lift into southern MO by late afternoon, driving additional
midlevel height falls and likely a second linear convective line
into the Midsouth. With the upper low in closer proximity, colder
air aloft will increase an initially low severe hail threat.
Effective CAPE during the afternoon will be limited by morning
rainfall and clouds, but likely sufficient given steepening
midlevel lapse rates and height falls.
Relatively quiet weather will prevail Sunday under shortwavelength
upper ridging. By Monday, a compact open northern branch wave will
drop into the lower/mid MS River valley. This system will feature
midlevel lapse rates in excess of 7 C/KM, along with 1km MUCAPES
in excess of 2000 J/KG - more than sufficient for severe storms.
Due to the steep lapse rates, Monday's storms will likely present
a pronounced large hail threat.
The midweek periods will see fair and warm conditions prevail
under ridging aloft.
Regarding late next week, the 00Z ECMWF continued to show a dual-
lobe upper low lifting from the southern plains into the mid MS
River valley. Similar to earlier runs, a negatively-tilted lobe
ejects across the Ozarks and Midsouth Thursday afternoon.
Conversely, the GFS has departed from earlier runs, showing the
upper low opening up and dropping into northern Mexico, while
phasing with a northwest flow northern branch trof over the
Midwest. Either solution impinges midlevel height falls onto a
moist and unstable warm sector over the Midsouth, resulting in
increased thunderstorm chances. However, the GFS solution would
bring cooler temps behind the exiting northern branch trof. For
the extended, have edged up model blended temps a bit, giving a
nod to the ECMWF's better interrun consistency with the late week
12Z TAF Set
Showers with a few embedded thunderstorms will continue pushing
east across West TN and North MS this morning. Winds behind the
line will become variable but should eventually turn around to
the south by this afternoon. Once the direction switches around to
south expect speeds to increase to 12-17 KTS sustained with gusts
between 20-27 KTS. Atmosphere could recover during the afternoon
hours for some redevelopment of thunderstorms. Although not as
confident as previous forecast. Have only mention of VCTS for now.
CIGS will bounce around from MVFR to VFR through the morning
hours. By this afternoon, expect VFR conditions to prevail at all
TAF sites unless impacted by redeveloping TSRAs.
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