Scientific Forecaster Discussion
fxus64 kmeg 191518
Area forecast discussion
National Weather Service Memphis Tennessee
1018 am CDT Fri Jul 19 2019
Another hot and muggy day on tap. Temperatures are generally in
the mid upper 80s at 10am...with heat indices in the upper 90s to
100f. Latest water vapor imagery shows upper level easterly flow
pushing into the mid-south at this hour. This will allow the ridge
to weaken a bit this afternoon and isolated showers and
thunderstorms to form. I went ahead and bumped up pops to slight
chance across much of the mid-south.
Highs will top out in the lower 90s again this afternoon...with
heat indices between 105-109 areawide. Based on a persistence
forecast, I do not anticipate having to upgrade the heat advisory
to an excessive heat warning at this time.
The rest of the forecast is on track with no further changes
Previous discussion... /issued 628 am CDT Fri Jul 19 2019/
Updated to include 12z aviation discussion.
Previous discussion... /issued 342 am CDT Fri Jul 19 2019/
hot and humid conditions will persist through the weekend, but a
significant pattern change is in store for early next week. A
broad ridge will exist over the Southern Plains and southeast
through Saturday with with 500mb geopotential heights maxing out
around 593 dam. A weak, upper-level low will move westward below
the subtropical ridge through Saturday, gradually lowering heights
over the southeast portion of the County Warning Area and creating a weakness in
the ridge by Sunday.
The building mid-level heights will help suppress diurnal
convection, generally confining rain chances to northeast MS and
portions of west Tennessee the next few days. Outside of these isolated
to scattered afternoon thunderstorms, hot and dry conditions are
expected with temperatures in the lower 90s. Dewpoints in the
75-77f range will support heat indices near 105f this afternoon so
the heat advisory looks to be in good shape. However, with
temperatures tomorrow trending slightly downward south of I-40,
the the greatest risk for heat indices greater than 105f will be
north and west of a line from Clarksdale, to Memphis, to Paris. A
similar trend is anticipated on Sunday although rain chances will
increase slightly and could limit heat indices further. That said,
a heat advisory is likely going to be need for portions of the
area on Saturday (and possibly Sunday as well).
A strong shortwave trough will dive southeast across the western
Great Lakes Sunday night, driving a cold front south across the
County Warning Area on Monday. There will be a good chance for showers and
thunderstorms with this system, mainly Monday into Monday night
with winds shifting around from the north behind the cold front.
Rain chances will linger south of I-40 on Tuesday but should
gradually end during the day as drier air settles over the mid-
south. As the aforementioned trough dives southeast early next
week, the ridge over the Southern Plains will quickly build over
the western Continental U.S. With a corresponding deep trough digging over
the east. Expect highs only in the mid 80s both Monday and
Dry weather and below normal temperatures are expected Wednesday
through Friday with the mid-south under northwest flow aloft and
northeast winds at the surface. Highs in the mid 80s and dewpoints
in the 60s will be a welcome relief following several days of
oppressive heat. Overnight low temperatures will be in the 60s
across most of the area behind this front with a few areas
potentially falling to near 60f Wednesday or Thursday morning.
VFR conditions will persist throughout the entire period. Winds
will be southerly at 10 knots or less this afternoon, becoming
calmer after sunset.
Arkansas...heat advisory until 8 PM CDT this evening for Clay-Craighead-
MO...heat advisory until 8 PM CDT this evening for Dunklin-Pemiscot.
MS...heat advisory until 8 PM CDT this evening for Alcorn-Benton MS-
Tennessee...heat advisory until 8 PM CDT this evening for Benton Tennessee-Carroll-