Tornado in Mississippi, April 18, 2017

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1042 AM CDT Tue Apr 18 2017

.UPDATE...
Updated for morning discussion.

&&

.DISCUSSION...
Made a few adjustments to POPs through the remainder of today.
Latest short term guidance rolling in this morning picks up on
some weak shortwave ridging to the northeast of the upper low.
Although enough moisture should be present to see some shower or
storm activity develop again this afternoon, lack of upper level
support may be enough to limit overall coverage especially for
areas south and east of the Natchez Trace. Also removed mention of
this morning's fog from the Hazardous Weather Outlook. /NF/

Prior discussion below:

Today and tonight...

Low clouds have been streaming into the region and some patchy fog
has also developed. While patchy, sometimes dense, fog will be
possible through morning hours(especially across eastern
Mississippi), think that low stratus will be more prevalent as
convective debris from activity in Texas moving into the CWA will
limit much fog development. Because clouds moving into the region
from the west will limit widespread fog, will hold off for now in
including anything in the HWO, but will continue to monitor trends
between now and daybreak.

Conditions today will be similar to the last few days as we remain
in this summer-like weather regime. Showers and thunderstorms will
once again develop across the region late this morning and through
the afternoon as temperatures rise into the lower 80s and combine
with a moist airmass in place(characterized by a 1.3-1.5 inch PW
value). At this point, it looks like the best coverage of storms
will be generally along and northwest of the Natchez Trace corridor
as a broad trough will remain in the vicinity of our region and a
stalled front remains to our north. As has been the case, a strong
storm cannot be ruled out during the peak afternoon hours along with
locally heavy downpours.

Storms will again diminish during the evening hours and another
round of fog looks likely once again tomorrow night. Lows will dip
into the 60s across the area. /28/

Wednesday through early next week...

Warm conditions will continue through the rest of the work week
with a pattern change not expected until this weekend as a strong
upper system and associated cold front sweep through the region.

Wednesday and Thursday will trend drier than the days prior due
to building upper level heights and increasing surface pressure
limiting diurnal convection chances. Thunderstorm development on
Wednesday and Thursday should be limited to areas near the Gulf
Coast where more moisture will be present and areas to the north
of the ArkLaMiss where moisture will begin to pool south of a slow
moving frontal boundary associated with a weak upper disturbance
that will cross the Great Lakes on Thursday. The stagnant Bermuda
high to our east will result in persistent low level southerly
flow through the mid week and late week period.

Expect temperatures to range 7-12 degrees above average Wednesday
through Friday with highs mainly in the mid to upper 80's. Went
slightly above temperature guidance on Wednesday and Thursday.

A deep upper level low will begin to develop over the western
Plains late in the work week, continuing to deepen as it treks
toward the mid Mississippi Valley. 00Z runs of the GFS and Euro
displayed more temporal displacement than the previous runs, with
the Euro about 12 hours faster than the GFS. Nevertheless, both
models continue to develop solutions indicative of severe weather
over the weekend. A moist, buoyant prefrontal airmass will exist
ahead of the associated front with SBCAPE values exceeding 2000
j/kg and lapse rates ranging from 6-7 C/km. As of now, all modes
of severe weather seem possible with storms forming ahead of and
along the frontal boundary as it sweeps through the region. Latest
guidance suggests that the surface front should be east of the
region by Sunday morning.

A cooler, drier airmass will filter into the ArkLaMiss behind the
front resulting in below normal temperatures on Sunday. Models
begin to diverge early next week but temperatures should begin to
warm to near normal values by Monday as an upper ridge builds.

&&

.AVIATION...
12Z TAF discussion:
Low clouds have been moving across the western part of the area
while some fog has developed in the east. TAF sites around
KJAN/KMEI/KHBG will continue to see lowered vis through 13Z.
Conditions will improve for all sites through the morning hours.
Additional showers and storms will occur today, especially for
sites along and northwest of the Natchez Trace corridor (KGLH/KGWO/KGTR/KJAN).
These storms will lead to some lowered MVFR to IFR ceilings and
vis restrictions through the afternoon into the early evening
before likely lifting back to VFR conditions. Patchy fog will
again be a concern tonight into early Wednesday morning. /28/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       81  60  86  62 /  20  18  10   5
Meridian      82  58  85  61 /  13  14  10   6
Vicksburg     82  61  85  64 /  23  19   9   4
Hattiesburg   83  59  86  61 /  10   6  11   6
Natchez       81  62  84  63 /  20  17  17   5
Greenville    80  63  84  65 /  28  21  10   4
Greenwood     78  63  85  64 /  34  18  11   4

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.

&&

JPM3/NF/28

Hazardous Weather Outlook...DELAYED
National Weather Service Jackson MS
1043 AM CDT Tue Apr 18 2017

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
191545-
Ashley-Chicot-Morehouse-West Carroll-East Carroll-Richland-
Madison LA-Franklin LA-Catahoula-Tensas-Concordia-Bolivar-
Sunflower-Leflore-Grenada-Carroll-Montgomery-Webster-Clay-Lowndes-
Choctaw-Oktibbeha-Washington-Humphreys-Holmes-Attala-Winston-
Noxubee-Issaquena-Sharkey-Yazoo-Madison MS-Leake-Neshoba-Kemper-
Warren-Hinds-Rankin-Scott-Newton-Lauderdale-Claiborne-Copiah-
Simpson-Smith-Jasper-Clarke-Jefferson-Adams-Franklin MS-Lincoln-
Lawrence-Jefferson Davis-Covington-Jones-Marion-Lamar-Forrest-
1043 AM CDT Tue Apr 18 2017

This hazardous weather outlook is for portions of southeast
Arkansas, northeast Louisiana, central Mississippi, north central
Mississippi, and south central Mississippi.

.DAY ONE...The rest of Today and Tonight

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

The probability for widespread hazardous weather is low.

.SPOTTER CALL TO ACTION STATEMENT...
The activation of storm spotters, HAM radio operators, and
emergency management personnel in support of severe weather
operations is not expected through next Monday.

NF

&&

...HAZARD LEGEND...

No short term hazards expected.

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