Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA
FXUS64 KLIX 280517
Area Forecast Discussion
National Weather Service New Orleans LA
1117 PM CST Mon Feb 27 2017
Onshore flow at a moderate clip should maintain a maritime cloud
deck in IFR ranges between 003-008 overnight most locations. If
winds relax/decouple, then some patchy fog may result, but this is
low confidence at this time. Low clouds should diabatically lift
into MVFR and VFR bases between 15-17Z and prevail at VFR levels
through remainder of the TAF valid period. 24/RR
.PREV DISCUSSION... /issued 738 PM CST Mon Feb 27 2017/
The sounding this evening depicts the unstable environment storms
across the northern part of the area and near the Mississippi Gulf
Coast were working with earlier today. Mixed layer CAPE is at 1500
J/KG, though without forcing current thinking is still that
tonight remains nearly dry. There is 42 kts of sfc to 6 km shear
with winds southerly at the sfc and becoming west with height.
Peak wind is 110 kts at 230 mb. PW is well above average at 1.5
PREV DISCUSSION... /issued 352 PM CST Mon Feb 27 2017/
For today the HRRR handled the area well...but coverage and
strength was more aggressive than what took place today. Fairly
strong helicity evident as some of the storms were rotating
today. Convection associated with the upper jet expected to
diminish through the evening as the upper support pulls off to the
north and east. General thunder only expected in the far SW
corner of MS for our area tomorrow. Warm and dry for Mardi Gras.
In fact, it could be close to the warmest Mardi Gras on record
which is currently 83 degrees.
A strong cold from is poised to enter the area Wednesday
associated with With the front comes a Marginal Risk of severe
weather east and west of a line across Lake Pontchartrain east to
the MS Gulf Coast. The Slight Risk touches our counties in SW MS.
Most of the energy will remain further north, however the tail end
of a squall line could produce gusty winds, small hail, and an
isolated tornado. ECMWF 0-2km lapse rates steepest around 18z over
the area with model helicity of 200 ms/ss mainly in SW MS south
to KBTR. Forecast sounding CAPE values decrease as the front
travels south from 1120 j/kg around Monroe at 06Z Wed to 490 j/kg
at KMSY at 00Z Thu. The area of thunderstorms are expected to
weaken as the systems moves south. Cold but dry conditions
following the front for the remainder of the week. Return flow
begins in south Texas Saturday with rain chances increasing again
late in the weekend to early next week.
VFR conditions expected until some localized fog and lower
ceilings Tuesday morning. BKN clouds will continue overnight with
OVC 1000-1500ft possible for a few hours Tuesday morning. Winds
will remain easterly without impacts to terminals.
The upper trough will continue to move east keeping winds mainly
10-15 knots. Bigger impact will be a cold front Wednesday with
winds increasing to over 20 knots in the offshore waters. Most
likely a Small Craft Advisory will be needed following the cold
front for the strong northerly flow. Some thunderstorms can be
expected as well associated with and ahead of the cold front.
DSS code: Blue.
Deployed: NOLA EOC.
Activation: None. Activities: Support for City of New Orleans
through Tuesday. Monitoring convective trends.
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 66 84 66 79 / 20 10 20 50
BTR 68 83 68 81 / 20 10 10 50
ASD 67 83 66 82 / 20 10 10 40
MSY 68 81 68 82 / 30 10 10 30
GPT 67 77 66 78 / 20 10 20 30
PQL 65 79 65 79 / 20 10 10 30