Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 261431 AAA

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
931 AM CDT TUE JUL 26 2016

.UPDATE...Visible imagery and area radars this morning showing a
surge of cloud cover and precip occurring over the far se and coastal
areas of ms. This associated with a mid level cold core system and
associated weak low level circulation over southeast LA. Consensus of
hires cam models are indicating that surface low will move northwest
this afternoon helping deep moisture (PWs ~ 2.3 in) move inland.
Convection will be enhanced over the southern half of the forecast
area due to better lapse rates and low level convergence./26/


.AVIATION...The threat for mainly diurnal SHRA/TSRA today and
especially Wednesday will begin to pose greater concerns for
hazardous aviation weather conditions, mainly along/south of the
HKS/JAN/MEI corridor today and at all sites Wednesday. Due to
increasing tropical moisture and lift, the threat for MVFR ceilings
will increase, especially during the early/mid morning hours
(although some MVFR ceilings will still be possible through the day
around HBG and MEI, even away from thunderstorms). Some storms today
could contain some gusty winds, especially in the afternoon hours.


.PREV DISCUSSION... /issued 459 AM CDT TUE JUL 26 2016/


Today through Wednesday night, A mid level trough and associated weak
surface low near the LA/MS coastline will shift slowly north across
the ArkLaMiss through a weakness in the subtropical ridge. Southerly
flow and deep layer moisture transport will increase later today
resulting in increasing convective rain chances for this afternoon
over southern and eastern MS. The threat for locally heavy downpours
could reach most of the area by this evening before waning later
tonight, although lift associated with the trough should help to
maintain at least isolated showers through the night. Poor lapse
rates (vertical totals < 25 deg C) will limit any severe storm
threat, but increasing southeast flow could support some storm
organization along nw-moving convective boundaries with strong wind
gusts possible during peak heating.

Precipitable water is expected to approach 2.5 inches by Wednesday
over much of the forecast area and the coverage of mostly diurnal
shower/thunderstorm age should be rather high given lift and moisture
convergence associated with the trough. While the tropical moisture
isn`t unusual by any means for this time of the year, the forecast
values are definitely on the upper edge of the typical envelope
according the SPC climatology page, and given the rather anomalous
flow (~2 to 3 SD H850 V component per NAEFS SAD table), we may
eventually need to monitor for the potential of locally excessive
rainfall. Poor lapse rates and relatively early development of the
convection will continue to limit any strong/severe storm threat.

Otherwise, we should see one more day with higher heat indices over
the Delta region and will keep a mention of this going in the
HWO/graphic, but expect the threat for dangerous heat stress to
diminish significantly Wednesday due to increased cloud/rain
coverage. /EC/

Long Term (Thursday through Monday)...A wetter and relatively -
added emphasis on relatively - cooler pattern will continue to be
the main theme through the long term.

In the upper levels, the center of the mid/upper ridge axis will
remain retreated to the western CONUS as weakness in this feature
invites subtle troughing over the east. The seeming permanence of
this setup throughout the extended period along with plentiful deep
layer moisture will make for higher rain chances through early next
week. In fact on Thursday the GFS is progging a PW of 2 - 2 1/2 in.
over the northwest half of the CWA. This type of environment will
lend itself to the potential for periodic convection both day and
night, thus somewhat higher POP was maintained overnight into
Friday. By the weekend, PW will return to more seasonable levels,
but greater than usual diurnal precip coverage is still anticipated.

Outside of any clouds and precip, it will still be quite warm and
uncomfortable, but the net effect will be slightly lower/near normal
high temperatures through early next week. /DL/


Jackson       92  74  88  74 /  42  42  63  39
Meridian      92  74  88  73 /  44  30  52  32
Vicksburg     93  75  88  74 /  29  42  66  53
Hattiesburg   90  74  89  74 /  63  42  60  26
Natchez       90  74  86  73 /  49  50  65  39
Greenville    96  76  88  74 /   9  37  66  68
Greenwood     95  75  87  74 /  14  29  59  64


.JAN Watches/Warnings/Advisories...


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