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

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FXUS64 KLIX 181242
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
642 AM CST Thu Jan 18 2018

.SOUNDING DISCUSSION...

Routine flight terminated northeast of D`Iberville, Mississippi at
a height of 88,800 feet or 16.8 miles above the surface.

Airmass remains extremely dry with a precipitable water value of
0.13 inches. The subfreezing layer is about 2,300 feet deep this
morning.

Northeast winds from the surface to just below 850 mb, northwest
winds to about 650 mb, then westerly to 50 mb. Max wind of 81
knots at 41,700 feet. 35

&&

.PREV DISCUSSION... /issued 316 AM CST Thu Jan 18 2018/

SYNOPSIS...

Another bone-chilling morning across southeast Louisiana and
southern Mississippi. Arctic high pressure centered over northern
Louisiana early this morning. No cloud cover across the area. With
the exception of lower Plaquemines Parish, all areas are seeing
temperatures in the upper teens and 20s. Already have broken
record low temperature at McComb (17), Pascagoula (23) and
Gulfport (24), and tied it at Slidell Airport (21).

SHORT TERM...

If we can deal with the cold for another 30 hours or so, we`ll
finally see temperatures remain above freezing. High pressure will
move slowly eastward and be centered over Georgia by Saturday
morning. We`ll run one more night with Freeze and Hard Freeze
Warnings tonight, but admittedly, it will be a close call as to
whether we actually verify the criteria.

A weakening southern stream shortwave will move across the area
late Friday into Saturday. Lower layers will be moisture starved,
and will continue the dry trend of the previous forecaster. GFS
and ECMWF mostly support this, although NAM just a little wetter.
Good part is that everyone will be comfortably above freezing
before anything happens.

Shortwave ridging should still keep Sunday dry. As onshore flow
kicks in, certainly at least some potential for marine fog to
develop by Sunday afternoon/night.

Temperatures will moderate into the 40s today and into the lower
to middle 50s on Friday. As onshore flow kicks in, will finally
see temperatures jump to a little above normal on Saturday, and
most areas will be 10 degrees or more above normal on Sunday.
Can`t see going above guidance on readings today into Friday, as
guidance usually a little quick to warm things up in return flow
after an arctic outbreak. Discounted MET highs on Saturday, as
this is predicated on precipitation and we have a dry forecast
going. 35

LONG TERM...

High amplitude troughing relaxes across the middle of the country
next week, with more of a southwesterly flow over the Mississippi
River Valley. This will keep the storm track just north and west
of the area for much of next week. This will bring a healthy
chance of showers and thunderstorms to the area Sunday night into
Monday, then perhaps another chance at the end of the week. High
temperatures during the next work week should be well into the 60s
in most cases, with lows in the 30s and 40s. 35

AVIATION...

VFR through taf cycle.

MARINE...

Strong arctic high pressure has built into the gulf coast and will
shift east by Friday bringing return flow back to the northern gulf
Friday night into Saturday. Foggy conditions near the coast could
develop over the weekend ahead of the next cold front which will
move through Monday. Thunderstorms are expected to accompany this
system over the gulf as it moves through as well as another stretch
of strong northerly winds.

DECISION SUPPORT...

DSS code: Blue.
Deployed: None.
Activation: None.
Activities: Hard freeze threat again tonight/Friday morning

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.
Yellow = Heightened impacts with short-fused watch, warning or
         advisory issuances; radar support.
Orange = High Impacts; Slight to Moderate risk severe; nearby tropical
         events; HazMat or other large episodes.
Red    = Full engagement for Moderate risk of severe and/or
         direct tropical threats; Events of National Significance.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  42  24  51  37 /   0   0   0   0
BTR  42  26  52  41 /   0   0  10   0
ASD  43  26  54  42 /   0   0   0   0
MSY  40  31  53  46 /   0   0   0   0
GPT  43  26  52  43 /   0   0   0   0
PQL  43  23  53  40 /   0   0   0   0

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Hard Freeze Warning until 11 AM CST this morning for LAZ034>037-
     039-040-046>050-056>072.

     Wind Chill Advisory until 9 AM CST this morning for LAZ034>037-
     039-040-046>050-056>072.

     Freeze Warning from 6 PM this evening to 10 AM CST Friday for
     LAZ056>065.

     Hard Freeze Warning from 6 PM this evening to 10 AM CST Friday
     for LAZ034>037-039-040-046>050-071-072.

GM...None.
MS...Hard Freeze Warning until 11 AM CST this morning for MSZ068>071-
     077-080>082.

     Wind Chill Advisory until 9 AM CST this morning for MSZ068>071-
     077-080>082.

     Hard Freeze Warning from 6 PM this evening to 10 AM CST Friday
     for MSZ068>071-077-080>082.

GM...None.
&&

$$



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