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

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FXUS64 KLIX 230933

Area Forecast Discussion
National Weather Service New Orleans LA
433 AM CDT Sun Apr 23 2017

Latest surface analysis showed a 1008mb low over northwest Georgia
with a cold front extending southwest to the Mississippi Delta to
northwest Gulf of Mexico and a 1024mb high over west Texas.
Northwest winds of 5 to 10 mph were across Louisiana and
Mississippi this morning. Latest upper air analysis and infrared
satellite imagery revealed a low/tight cyclonic circulation over
west Tennessee with an axis extending southwest.


Upper level low will continue to deepen over the Tennessee Valley
as the associated axis sweeps southeast across the forecast area
today. While the surface front continues to move southeast, the
passage of the upper level trough will yield strong cold air
advection, especially at the lowest layers. 1000 to 850mb layer
was hovering around 1400m across the forecast area. This will
decrease to 1350 over southern Mississippi to 1370 over the
Mississippi Delta by this afternoon. This feature along with the
surface pressure gradient will yield northwest winds of 10 to 15
mph with higher speeds of 15 to 25 mph south of tidal lakes this
afternoon. Sea surface temperatures of Lake Pontchartrain are
hovering between 76 and 80F. Cool air over warm waters will allow
boundary layer winds to mix down and elevated winds will stay in
play along the south shores of tidal lakes today through Monday

The upper level low is expected to move east Monday and upper
level flow will weaken and become more westerly over the area.
Ridge axis will start to build in across the Lower Mississippi
Valley Monday afternoon and evening. As a result, cold air
advection will end Monday. Surface high and dry air will settle
over region Monday night with cool temperatures but less winds.


Surface high will shift east Tuesday. Another upper level trough
is expected to move across the Central Plains. This will yield a
lee side trough over Central and Southern Plains. Moisture return
will be slow at first, but south flow ahead of the surface
trough/front will bring in moisture over east Texas early Wednesday.
Surface front will push east across the forecast area Wednesday
night. Precipitable water values up to 1.6 inches will pool along
and ahead of front. The associated dynamics will sweep across
Arkansas and Missouri. Surface base cape values increase up to
1500 to 2200 j/kg and helicity around 200 m/s are possible across
the north half of the forecast area Wednesday night according to
GFS. Have inserted chance of convection for Wednesday night into
early Thursday. In addition, will mention the threat of strong
storms for mid week in the outlook.

Not much of a passage with the mid week system as instability and
moisture should return by Thursday night. As a result, there will
be a slight chance of some convection Friday and Saturday. For
next weekend, GFS and ECMWF show a nearly full latitude from the
Dakotas to Texas. Moisture and instability will be in play and we
have inserted likely rain chances for Sunday Day 8.


Thunderstorms have exited the region as a cold front pushes through
the area. Lingering showers will pass through over the next few
hours but should taper off by this afternoon. VCSH may not be needed
after sunrise due to the isolated nature of showers. IFR to MVFR
ceilings will persist through the morning at all terminals due to
low level clouds. VFR conditions will begin to return from south to
north as cloud cover erodes this afternoon. MCB will be the last to
see clear skies.


Cold front is currently moving through the area. The boundary has
moved through the tidal lakes and Mississippi sound and will
progress over the rest of the coastal waters early this morning.
After a brief jump into the low 20kts range, winds should settle
into the mid/upper teens. Therefore, will have exercise caution
headline for all coastal zones today. Nocturnal wind enhancement
from cold air advection will bring winds into the small craft
advisory range this evening. SCA conditions will be fairly short-
lived as weakening pressure gradient allows winds to relax back into
the exercise caution range after midnight. Offshore winds will
persist through Monday night and switch back to onshore Tuesday as
surface high pressure shifts east of the area. Wind speeds will
generally be moderately strong throughout the rest of the week as
series of surface lows track across the midsection of the country.


DSS CODE...Blue.
ACTIVITIES...Monitoring severe potential Saturday afternoon and

Decision Support Service (DSS) Code Legend:
GREEN  = No weather impacts that require action
BLUE   = Long fused Watch/Warning/Advisory in effect or high
         visibility event
YELLOW = Heightened impacts with short fused
         Watch/Warning/Advisory issuances; Radar support
ORANGE = High Impacts - Slight to Moderate risk of severe weather;
         Nearby tropical events, HAZMAT or other large episodes
RED    = Full engagement for moderate risk of severe weather; Direct
         tropical threats; events of national significance.


MCB  64  46  77  51 /  10   0   0   0
BTR  68  49  77  54 /  10   0   0   0
ASD  70  50  78  55 /  20   0   0   0
MSY  70  55  77  59 /  20   0   0   0
GPT  72  53  78  60 /  20   0   0   0
PQL  72  47  78  55 /  20   0   0   0


GM...Small Craft Advisory from 6 PM this evening to 1 AM CDT Monday
     for GMZ530-532-534-536-538-550-552-555-557-570-572-575-577.

GM...Small Craft Advisory from 6 PM this evening to 1 AM CDT Monday
     for GMZ532-534-536-538-550-552-555-557-570-572-575-577.


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