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

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FXUS64 KLIX 162141
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
341 PM CST Sat Feb 16 2019

.SHORT TERM...
A weak cold front was draped near the Mississippi coast and across
the coastal areas of southeast Louisiana this afternoon. This
boundary will move back north as a warm front tonight before
moving back south as a cold front late Sunday and Sunday night.
The main concern in the short term is the potential for dense fog
tonight and Sunday morning. Currently, dense fog is situated
across some of the nearshore waters...just off the coast. Only
patchy fog was being observed inland across the southeast
Louisiana coastal zones. As the frontal boundary moves back to
the north tonight, fairly widespread fog is forecast to
advect/develop inland later this evening and overnight and persist
into Sunday morning. At least moderate fog is anticipated with
areas of dense fog possible. At this time, we will hold off on
issuing a dense fog advisory and let the evening shift reevaluate
the potential for dense fog as the evening progresses. The best
chance for dense fog will likely be near and over bodies of
water. As the cold front approaches later Sunday into Sunday
night, rain chances will be on the increase and progress southeast
through the overnight hours as a short wave trough passes well to
out north. 11

.LONG TERM...
A wet pattern is forecast to prevail through the week with some
potential for heavy rain and possibly even some severe weather.
Southwesterly flow aloft will prevail during the period while a
couple of potent short wave troughs move out of the western conus
and into the central U.S. during the week. In addition, a number
of impulses embedded in the southwesterly flow will traverse the
lower Mississippi Valley while a frontal boundary becomes draped
across the area. At this time it appears the the axis of heaviest
rain will be to the north of the forecast area during the week;
however, periods of heavier rain are still possible across the
local forecast area...especially across southwest Mississippi
where 3 or 4 inches are possible during the course of the week.
Precipitable water values are forecast to approach 1.9 inches
from early Wednesday into Wednesday night. This is a timeframe
when some heavier rain amounts will especially be possible along
with a potential threat for severe weather as instability and
shear increases as a short wave trough moves across the central
conus. The threat for showers and thunderstorms will continue into
next weekend until another short wave trough moving out of the
west and across the central U.S. finally pushes the frontal
boundary and moisture to the east of our area. 11

&&

.AVIATION...
Conditions continue to slowly improve across area terminals with fog
dissipating due to afternoon mixing. A slow moving cold front has
sagged south across Lake Pontchartrain and Maurepas, but will likely
begin to retreat north as a warm front later tonight. This will help
drag fog back north overnight tonight to generally all terminals
through early to mid morning tomorrow. The extent and coverage of
how dense the fog will be is still in question. However, generally
given the moist gulf onshore flow, patchy areas of dense fog should
be expected with low CIG`s reducing flight categories to periods of
IFR/LIFR. KLG

&&

.MARINE...
Latest satellite and metar observations continue to illustrate areas
of low clouds and patchy dense fog across near-coastal zones this
afternoon. Farther inland, a slow moving cold front has sagged south
across Lake Pontchartrain and Maurepas which has pushed
out/dissipated fog across near coastal lakes. For tonight, this
front will begin to retreat back north as a warm front, lifting well
north of the marine zones. However, increasing moist southerly
onshore winds will likely drag fog back north across near coastal
lakes later tonight. All marine zones near the coast and within the
lake will likely experience dense fog, at or lower than 1 mile
through early tomorrow morning. Marine highlights will be determined
later this evening/early tonight for potential re-issue of marine
fog highlights. Otherwise, much of the same can be expected on
Sunday, before the next cold front swings through the area late
Sunday evening/Sunday night causing a shift in winds. Following this
frontal passage, gusty winds will increase through early Monday
morning, generally from the NE with increasing wave heights ranging
3-5 feet. Marine highlights during this time frame will likely be
necessary as we approach this time frame, but will be evaluated
closer tomorrow/tomorrow night. Following early next week we stay in
this active weather pattern, as persistent SW flow aloft keeps high
anomalous precipitable water values across the area. Expect periods
of strong winds, frontal passages and associated shower/storm
chances through next weekend. KLG


&&

.DECISION SUPPORT...
DSS code: Blue.
Deployed: None.
Activation: None.
Activities: River Flood Warnings and marine Dense Fog Advisory

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 rain; direct tropical threats; Events of National
         Significance.


&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  59  72  47  62 /  20  70  30  10
BTR  64  74  50  63 /  20  70  30  20
ASD  65  75  53  65 /  20  20  40  20
MSY  66  76  56  63 /  20  20  40  30
GPT  65  71  55  64 /  10  10  50  30
PQL  66  73  57  66 /  10  10  50  40

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Dense Fog Advisory until 9 AM CST Sunday for GMZ536-538-550-552-
     555-557.

MS...None.
GM...Dense Fog Advisory until 9 AM CST Sunday for GMZ538-550-552-555-
     557.

&&

$$


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