Area Forecast Discussion
Issued by NWS Memphis, TN

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FXUS64 KMEG 230159

Area Forecast Discussion
National Weather Service Memphis TN
859 PM CDT Mon May 22 2017

A shortwave trough is moving east across the Southern Plains this
evening, accompanied by a strong upper-tropospheric jet streak.
The combination of strong forcing for ascent downstream of this
wave and warm advection above the boundary layer has resulted in a
fairly strong ageostrophic vertical circulation, likely enhanced
by the upper level jet dynamics. There is very little lightning
activity with this precipitation which is more stratiform in
nature, rather than the typical convective type observed in May.
Rainfall amounts remain relatively light with ceilings still near
10,000 ft across much of the area.

Rain should diminish Tuesday morning, but the next system will
bringing the potential for showers and thunderstorms back into the
forecast for Tuesday afternoon, mainly west of the Mississippi
River. These showers and thunderstorms will overspread the Mid-
South Tuesday night into Wednesday. The PoP forecast looks to be
in good shape overnight, although rain chances were tapered down a
bit after midnight. Otherwise, only minor changes were made to
the forecast.



.PREV DISCUSSION... /issued 322 PM CDT Mon May 22 2017/


Currently...A 1020 mb surface high pressure sits over the region
while a 120 kt upper level jet streak moves across Texas. This
feature is helping to generate a large area of rain over the
Lower Mississippi Valley. High clouds from this system are
covering much of the Mid-South except the very northern part of
the forecast area along the MO/KY borders. This pattern looks
more reminiscent of the cool season in the Mid-South than late
spring. Temps range from 70 to 75 across the area with a light
easterly breeze.

Tonight...The aforementioned jet streak will slide east tonight
and the shield of rain will scrape North Mississippi. Increased
pops especially toward Monroe county since latest short term
models are fairly wet in that region. A few sprinkles are
possible north to about I-40. Clouds and rain will keep temps a
couple of degrees warmer overnight than the previous forecast.

Tuesday through Wednesday night...The Mid-South is in between
systems with the southern system departing to the east and
another piece of energy approaching from the west. Placed
slightly higher pops across NE Mississippi to account for the
departing system and slighter higher pops in NE Arkansas and the
MO Bootheel for the incoming system. All in all though most
places will remain dry for much of the day with temps in the mid
to upper 70s. A potent shortwave will rotate through Tuesday
night with numerous showers and a few thunderstorms. A deep upper
low will move over the Mid-South by Wednesday with cool conditions
and continuing chances for showers. Highs will mostly be in the
upper 60s. Rain chances will taper off Wednesday night as the
upper low departs.

Thursday and Friday...Weak ridging at the surface and aloft build
over the region as dry weather returns. Thursday will be a prefect
day with highs in the 70s and low humidities. Humidities start to
return on Friday as southerly winds develop on the backside of
the departing surface ridge of high pressure. Friday will be
breezy as well and temps will be back in the mid 80s.

The weekend into Monday...A cold front stalls north of the region
with a moist and unstable airmass over Mid-South and fast moving
WSW flow aloft. Several upper level disturbances move through
during this time frame that could trigger showers and
thunderstorms especially across the north. Toward the end of the
weekend a more significant upper trof may move through along with
a cold front with a drying trend by Monday. There is some
potential for some strong to severe storms during this time frame
but timing is very uncertain will leave mention out of the HWO
for now.



00Z TAFs

MVFR visibilities are possible late tonight towards Tuesday
morning at JBR/TUP. Otherwise, VFR conditions expected to prevail
for much of the period. A series of upper level shortwave troughs
will bring rain showers to TUP tonight and VCSH/VCTS to TAF sites
Tuesday afternoon. Light winds expected through much of the





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