Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA

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000
FXUS64 KLIX 232048
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
348 PM CDT Mon Apr 23 2018

.SYNOPSIS...

Latest surface analysis showed a 1012mb low over western
Tennessee with an occluded/cold front to north Georgia to Florida
Panhandle. Upper air analysis revealed a low on top of the
surface low and trough from Montana to Wyoming. West to northwest
winds were present across the forecast area this afternoon. With
the close proximity of the upper level low, wrap around moisture
and clouds were spreading across our northern zones, southwest
Mississippi and northern parts of the Florida parishes.

&&

.DISCUSSION...
Vertically stacked system will slowly progress east to the Eastern
Seaboard by Wednesday morning. While technically we had a cold
frontal passage, this feature did not usher in very dry air.
Surface pressure gradient will continue to relax tonight through
Wednesday. Temperatures overnight will fall and atmosphere at the
surface will become saturated tonight and Tuesday night, mainly
across the northern zones. Therefore, we maintain the patchy fog
wording across northern zones tonight and Tuesday night. Cloud
cover may hamper temperatures from falling in spots tonight. Fog
coverage is expected to develop earlier and slightly more
expansive across the north zones Tuesday night into Wednesday
morning.

The trough approaching the Northern Plains is expected to dive
southeast through this week and reach the Lower Mississippi Valley
late Wednesday into Thursday. Precipitable water values will
increase up to 1.4 inches ahead of the trough Wednesday night into
Thursday. Southeast flow does not really develop ahead of the
trough and associated front and only marginal instability will be
in play. Will insert isolated thunder due to the frontal focus
late Wednesday night and Thursday. A secondary wave is expected
Friday afternoon and evening. Precipitable water values are
expected to fall to a half inch early Friday across the forecast
area and increase up to an inch along this second wave. Will
maintain isolated showers as no instability will be available. A
pleasant dry weekend is expected with temperatures below normals.

&&

.MARINE...

The pressure gradient has weakened slight more than expected.
Surface observations as a general do not support an exercise caution
headline. Thinking winds will more consistently fall in the 10 to 15
knot range rather than above that. Tuesday and Wednesday will see a
similar offshore wind regime as high pressure builds in from the
north. Actual wind direction will vary from northwest to northeast
as the ridge to the north slides east.  A reinforcing front will
slide through Wednesday night as a weak upper trough tracks across
the southeast. A surge of drier air behind this front could push
winds back to around 15 knots Thursday morning. Winds should quickly
drop back to around 10 knots by the afternoon, and remain out of the
northwest around this speed through Friday. A third frontal passage
could once again push winds back to 15 to 20 knots over the open
Gulf waters for Friday night and early Saturday.

MEFFER
&&

.AVIATION...

Visible satellite shows wide swath of cumulus clouds wrapping around
a low pressure centered near the MO/AR/TN/KY intersection.
These clouds are bringing ceilings down into the MVFR range. These
conditions, bordering VFR and MVFR will persist through much of the
TAF period until the low lifts north and east tonight.

MEFFER

.DECISION SUPPORT...

DSS code: Blue.
Deployed: None.
Activation: None.
Activities: Sandhill Crane NWR Outreach Support
            New Orleans Navy Week Support

Decision Support Services (DSS) Code Legend
Green  = No weather impacts that require action.
Blue   = Long-fused watch, warning, or advisory in effect or high
         visibility event; Marginal risk severe or excessive rain.
Yellow = Heightened impacts with short-fused watch, warning or
         advisory issuances; radar support for Slight risk severe or
         excessive rain.
Orange = High Impacts; Enhanced risk severe; nearby tropical events;
         HazMat or other large episodes.
Red    = Full engagement for Moderate to high risk of severe and/or
         excessive rainfall; direct tropical threats; Events of
         National Significance.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  52  75  54  77 /  10  10   0  10
BTR  55  78  56  80 /   0   0   0  10
ASD  57  77  57  78 /   0  10   0  10
MSY  59  78  61  78 /   0   0   0  10
GPT  59  77  59  77 /   0  10   0  10
PQL  57  76  57  77 /  10  10   0   0

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&

$$



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