Daily General Weather Discussion Thread #17

CWOP weather station temperatures at 2:15pm:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
323 PM CST TUE DEC 15 2015


.DISCUSSION...CLEAR SKIES AND LOW RELATIVELY HUMIDITY VALUES TODAY
CAN BE VERY DECEIVING AS WEATHER CONDITIONS 24 HOURS FROM NOW WILL
BE QUITE DIFFERENT. A DEEP TROUGH HAS DROPPED SOUTHEAST FROM THE
PACIFIC NW WITH AN EMBEDDED CLOSED LOW RACING NORTHEAST ACROSS THE
CENTRAL PLAINS. MOISTURE LEVELS WILL BEGIN TO RISE ON OVERNIGHT AS
SFC RIDGE TO THE NORTHEAST BRINGS HAS ALLOWED WINDS BRING THE RETURN
OF ONSHORE FLOW. MODEL SOUNDS INDICATE PRECIP WATER VALUES RISING
FROM BARELY A QUARTER OF AN INCH TODAY TO WELL OVER 1.5 INCHES
MIDDAY WED. A COLD FRONT ASSOCIATED WITH THE UPPER LOW WILL BE
APPROACHING THE TX/LA BORDER EARLY WEDNESDAY MORNING. SHOWERS WILL
BEGIN TO DEVELOP OUT AHEAD OF THE SYSTEM BUT NOT UNTIL EARLY WED
MORNING. THE HRRR SHOWS LIGHT SHOWERS CLOSING IN ON THE CWA FROM THE
WEST AND GULF MAINLY AFTER 06Z TONIGHT...SO HAVE ADJUSTED POPS
ACCORDINGLY WITH SLIGHT CHANCE TO CHANCE ALONG THE COASTAL AREAS AND
LESS THAN ISOLATED FURTHER INLAND. MODELS IN GOOD AGREEMENT THAT THE
FRONT WILL REACH WESTERN PORTIONS OF THE CWA AROUND NOON WEDNESDAY.
NO SIGNIFICANT CHANGES MADE TO POPS FOR WEDNESDAY. PLUME OF MOISTURE
SATURATE THE COLUMN AND LIFT ALONG THE BOUNDARY COMBINED WITH
PRESSURE FALLS WILL PROMOTE WIDESPREAD SHOWER DEVELOPMENT. MODEL
SOUNDINGS SHOWING SLIGHTLY MORE INSTABILITY THAN PREVIOUS RUNS BUT
STILL FAIRLY MEAGER AND ALL ELEVATED. THE INSTABILITY WILL BE
GREATEST ALONG THE COAST IN THE "WARM SECTOR". IF THERE ARE ANY
STRONGER STORMS...IT WILL BE IN THIS REGION. MAIN THREAT WILL BE
STRONG DOWNDRAFT WINDS. THINKING IT WILL BE MORE OF AN SPS DAY
RATHER THAN SVR ONE IF ANY STORMS INTENSIFY.

BACK SIDE OF THE RAIN TO BE COMING ACROSS THE CWA THURSDAY MORNING.
ALTHOUGH THERE MAY STILL BE SHOWERS IMPACTING COASTAL PARISHES AND
COUNTIES OF LA AND MS....THIS ACTIVITY SHOULD BE OFFSHORE BY AROUND
NOON. STRONG HIGH PRESSURE WILL THEN BUILD IN THROUGH THE REST OF
THE WEEK AND MOST OF THE WEEKEND. A MORE SUBSTANTIAL DROP IN TEMPS
EXPECTED WITH THIS BOUNDARY AS THIS TROUGH WILL TRANSFER MORE
CONTINENTAL AIRMASS THAN PREVIOUS. LOOKING LIKE HIGHS IN THE UPPER
50S AND LOWER TO MID 30S FOR NIGHTTIME LOWS ALONG AND NORTH OF I-12
FOR A COUPLE DAYS BEFORE GRADUALLY MODERATING BACK TO CLIMO NORMS
LATE WEEKEND/EARLY NEXT WEEK.

1.74 inches at the house in Mandeville

Sent from my SM-N910V using proboards

Could be quite a storm system shaping up...

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Much of Southeast Louisiana has seen 1-3" of rainfall within the past 7 days, leading to already close-to-saturated grounds. An additional 2-4+" of rainfall appears possible (w/ locally higher amounts) Monday through Wednesday, with the greatest amounts likely coming on Tuesday.

With any additional rain, we're going have to monitor for potential street flooding if a bulk of the rain falls within a short period of time. The SPC has also introduced a marginal risk for severe thunderstorms on Monday within their 3-Day convective outlook & I would expect them to extend that into Tuesday as well. Stay tuned, enjoy today & tomorrow's nice weather!

The ECMWF continues to dump widespread totals of 5-8 inches of rain on our area between now and Christmas Day.