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Area forecast discussion...updated 
National Weather Service Memphis Tennessee
637 am CDT Tuesday Jun 30 2015

updated for 12z aviation discussion below.


Previous discussion... /issued 456 am CDT Tuesday Jun 30 2015/

Discussion...water vapor satellite/WSR-88D VAD wind profiles this
morning indicate a weak 850 mb low level jet over north
Mississippi early this morning. This low level jet streak combined
with ample moisture...instability...and a weak surface boundary
across portions of Arkansas were responsible for the regenerative
showers and thunderstorms which affected areas mainly south of
I-40 last evening into the overnight hours. Temperatures as of 4
am CDT are in the lower to middle 70s at most locations. Strong to
severe thunderstorm potential throughout the forecast along with a
potential for heavy rainfall at times are the predominant forecast
concerns in this morning/S forecast issuance.

Latest knqa/kgwx WSR-88D radar trends this morning indicate the
majority of the shower and thunderstorms have moved into northern
Alabama and northeast/central Mississippi. Latest short term model
trends show a potential for redevelopment of showers and
thunderstorms across the middle south later this afternoon as another
middle level shortwave trough embedded within northwest flow aloft
moves across the lower Mississippi Valley this afternoon.
Moderately stable middle level lapse rates combined with surface
based cape values at or above 3000 j/kg...and precipitable water
values around 1.75 inches suggests a potential for a few strong to
severe thunderstorms with damaging winds as the primary threat and
hail as a secondary severe weather threat. Localized flash
flooding from heavy rainfall will also be possible. High
temperatures this afternoon will be in the upper 80s to lower 90s
with the warmest readings occurring along the Mississippi River.
Shower and thunderstorm chances may persist into tonight across
the forecast area but will lean towards isolated probability of precipitation as
confidence in coverage and timing is low at this time.

Models still indicate an increasing potential for mesoscale
convective system /MCS/ development across portions of the middle
and lower Mississippi valleys Wednesday through the Fourth of
July as a series of shortwaves rotate trough the region. Strong
to severe thunderstorms are possible at times along with a
potential for heavy rainfall across the middle south. Exact
timing/placement of the mesoscale convective system development is somewhat uncertain at
this time. Later shifts may need to assess the potential for a
Flash Flood Watch as current model trends suggest rainfall amounts
may be perhaps between 3-6 inches during this period. Stay

Long term models indicate an upper level ridge axis will slowly
try to build into the lower Mississippi Valley next week with
shower and thunderstorm chances being driven predominantly by
daytime heating.



12z tafs

Light southwesterly winds and VFR to prevail through the next 24
hours. While isolated thunderstorms and rain cannot be ruled out in the heat of the
afternoon...GFS lamp...hrrr and 06z NAM guidance suggest main
convective focus will lie to the south and southeast of
outgrowth of the early morning activity.

For tonight...06z NAM depicted best chance of isolated thunderstorms and rain appears
will be east of mkl. As is typical in upper level northwest synoptic
flow...afternoon convective trends will have an influence on the
evening transition to elevated thunderstorms and rain. For now...confidence not
sufficiently high for ts mention beyond 00z.



Meg watches/warnings/advisories...


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