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

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209
FXUS64 KLIX 311255
AFDLIX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
655 AM CST SAT JAN 31 2015

...SOUNDING DISCUSSION...

ONCE AGAIN THERE IS A STRONG TEMPERATURE INVERSION AND THIS
MORNING IT IS FROM THE SURFACE TO 3200 FEET OF 9 DEGREES CELSIUS.
THE LOW-LEVELS ARE QUITE DRY AND THIS IS A LAYER WHERE WINDS ARE
PREDOMINATELY FROM THE EAST AND SOUTHEAST DUE TO THE AREA OF
SURFACE HIGH PRESSURE MOVING EAST ACROSS THE TENNESSEE AND OHIO
VALLEYS. TOWARD THE TOP OF THIS DRY AIR ABOVE 14000 FEET...WINDS
SWITCH AND BECOME FROM THE WEST AND NORTHWEST. THIS IS BRINGING IN
MORE MOIST AIR FROM OUR NEXT WEATHER SYSTEM TO OUR WEST ENTERING
THE SOUTHERN PLAINS. A PEAK WIND SPEED OF 75 KNOTS WAS LOCATED NEAR
40700 FEET.

12Z BALLOON INFO: A ROUTINE FLIGHT THIS MORNING LASTING 104 MINUTES.
THE BALLOON REACHED A HEIGHT OF 20.4 MILES ABOVE THE GROUND BEFORE
BURSTING NEAR SHIP ISLAND 52 MILES DOWNRANGE FROM THE OFFICE.

ANSORGE

&&

.PREV DISCUSSION... /ISSUED 430 AM CST SAT JAN 31 2015/

SHORT TERM...OTHER THAN MORE HIGH CLOUDS OVERNIGHT THAN WAS
EXPECTED IT HAS BEEN QUIET. THIS HAS HAD AN OBVIOUS HIT ON TEMPS
WITH MORNING LOWS LIKELY GOING TO BE ABOUT 5 DEGREES OR SO WARMER
THAN FCST. THINGS WILL BEGIN TO TRANSITION LATER TODAY AND MORE SO
TONIGHT WITH A WET FORECAST TOMORROW AND THROUGH SUNDAY NIGHT. AT 9Z
TEMPS RANGED FROM THE MID 40S TO LOWER 50S AND WE WILL LIKELY ONLY
SEE ABOUT ANOTHER 5 DEGREE DROP FOR THE MORNING LOWS.

FOR THE ENTIRE FCST THE MAIN PROTAGONISTS WILL BE A CUTOFF LOW
CURRENTLY OVER THE BAJA AND A PERSISTENT L/W TROUGH PATTERN OVER THE
ERN CONUS. THE FIRST 60 HRS OF THE FCST WILL BE DOMINATED BY THE
EFFECTS OF A STRONG NRN STREAM S/W THAT HAS DROPPED OUT OF
BC...CANADA AND INTO THE BIG SKY COUNTRY. THIS S/W WILL CONTINUE TO
DIVE SE INTO THE CNTRL PLAINS AND MID MS VALLEY AND UPPER PORTIONS
OF THE LOWER MS VALLEY BY SUN NIGHT. THIS WILL LEAD TO LEE SIDE
CYCLOGENESIS TONIGHT WITH THE SFC LOW DEEPENING AS IT MOVES EAST
ACROSS THE CNTRL PLAINS AND INTO THE OH RIVER VALLEY SUN NIGHT WHILE
DRIVING A COLD FRONT TWRDS OUR AREA SUN NIGHT. AT THE SAME TIME A
PIECE OF ENERGY WILL BREAK OFF OF THE BAJA LOW AND MOVE INTO THE
LOWER MS VALLEY SUN. THE COMBINED IMPACTS OF THE NRN STREAM S/W AND
SRN STREAM DISTURBANCE WILL LOWER HGHTS SOME 7 DM LATE TONIGHT AND
THROUGH THE DAY SUN. MOISTURE WILL START TO INCREASE LATER TODAY AS
WE MOVE UNDER WEAK SW FLOW IN THE MID AND UPPER LVLS AND LL FLOW
VEERS AROUND TO THE SE. PWS WILL INCREASE FROM A PALTRY 0.28 (LAST
NIGHTS SNDG) TO AROUND 1.25 INCHES OVERNIGHT TONIGHT.

FIRST SHOT OF SHRA MAY OCCUR DURING THE EARLY MRNG HRS SUN AND
THROUGH MIDDAY OVER THE SERN HALF OF THE CWA. THIS ACTIVITY WILL BE
ASSOCIATED WITH THE SRN STREAM DISTURBANCE ALONG WITH AN H85 THETA E
AXIS THAT WILL SLOWLY MOVE ACROSS THIS REGION. HAVE TRIED TO SHOW
THIS IN THE GRIDS WITH BEST RAIN CHANCES ACROSS THE SERN PORTIONS OF
THE CWA EARLY BUT AS WE MOVE INTO THE AFTN RAIN WILL LIKELY TAPER
OFF SOME FOR THE SRN HALF AND START TO INCREASE ACROSS OUR EXTREME
NW ESPECIALLY LATE IN THE AFTN AND EARLY IN THE EVNG. THIS WILL BE
IN RESPONSE TO THE EFFECTS OF THE NRN STREAM S/W AND APPROACHING
COLD FRONT. IN ADDITION A FEW EMBEDDED TSRA WILL BE POSSIBLE SUN
AFTN/EVNG AS THERE WILL BE A LITTLE INSTABILITY TO WORK WITH.

RAIN WILL BEGIN TO COME TO AN END AFTER MIDNIGHT SUN NIGHT AS THE
COLD FRONT STARTS TO PUSH INTO THE REGION. MUCH COLDER AND DRIER AIR
WILL WORK INTO THE AREA MON WITH A FAIRLY CHILLY DAY IN STORE MON.
H925 TEMPS DROP TO AROUND -1C TO 3C ACROSS THE CWA AND THIS WOULD
YIELD HIGHS ONLY GETTING INTO THE MID/UPPER 40S TO MID 50S ACROSS
THE REGION. THERE SHOULD BE A LITTLE OF A BREEZE AND THIS COULD HELP
KEEPS THINGS MIXED LEADING TO HIGHS A TAD COOLER THAN WHAT GUI IS
CURRENTLY ADVERTISING AND HAVE NUDGED THINGS A DEGREE OR TWO LOWER.

LONG TERM...OVERALL THE MEDIUM RANGE MDLS APPEAR TO BE A LITTLE
MORE IN LINE BUT THE EURO IS THE SLOWER MDL AGAIN WHEN COMPARED TO
THE 12Z RUNS...AND THIS IS AT ODDS WITH THE 00Z RUN LAST NIGHT WHERE
IT WAS THE FASTER. THE GFS HAS BY FAR BEEN THE MORE CONSISTENT MDL
BUT THE EURO IS NOT DRASTICALLY DIFFERNT SO A BLEND OF THE TWO WITH
A CONTINUED SLIGHT LEAN TWRDS THE GFS APPEARS TO BE THE BETTER SOLN
HERE. THE GFS DOES HAVE SUPPORT FROM THE GEM AND THE GFES.

A QUIET AND COLD NIGHT WILL BE STORE MON NIGHT AS THE SFC HIGH MOVES
RIGHT OVER THE REGION. CLEAR SKIES...DRY AIR...AND RATHER LIGHT
WINDS SHOULD SET THE STAGE FOR DECENT RAD COOLING CONDITIONS AND WE
COULD SEE A LIGHT FREEZE FOR MUCH OF THE NRN HALF OF THE CWA BY TUE
MORNING. THE ONE FLY IN THE OINTMENT FOR MRNG LOWS TUE WILL BE HOW
MUCH RAIN WE RECEIVE SUN AND SUN NIGHT AND THE RESULTING GROUND
MOISTURE LEFT IN PLACE. AFTER THAT THINGS WILL QUICKLY CHANGE. THE
SFC HIGH WILL SHIFT EAST WITH RETURN FLOW SETTING UP. THE BAJA LOW
WHICH BY LATE MON WOULD HAVE DUG TWRDS THE SRN PORTIONS OF THE BAJA
WILL FINALLY BEGIN TO LIFT OUT ACROSS MEXICO AND INTO SRN TX LATE
TUE NIGHT. A SFC LOW WILL DEVELOP OVER THE NWRN GULF AT THE SAME
TIME AND TRAVERSE ACROSS THE NRN GULF WED AND TWRDS FL THU. THE OLD
BAJA LOW WILL CONTINUE TO WEAKEN AND OPEN UP AS IT MOVES INTO THE
LOWER MS VALLEY WED AND WED NIGHT. THIS WILL LEAD TO HIGH RAIN
CHANCES WED AND INTO EARLY THU. LIGHT SHRA COULD BEGIN AS EARLY AS
TUE AFTN BUT LIKELY HOLD OFF FOR THE MOST PART UNTIL TUE NIGHT.

TEMPS WILL BE BELOW NORMAL THROUGH THE FCST BUT OUTSIDE OF TUE
MORNING THEY WILL NOT BE SIGNIFICANTLY BELOW NORMAL. /CAB/

AVIATION...

VFR CONDITIONS WILL PREVAIL THROUGH AT LEAST 06Z SUNDAY AT ALL
TERMINALS. CLOUDS WILL CONTINUE TO INCREASE THROUGHOUT THE PERIOD
WITH CONDITIONS SLOWLY DETERIORATING OVERNIGHT SATURDAY INTO SUNDAY
MORNING.

MARINE...

SMALL CRAFT EXERCISE CAUTION REMAINS IN AFFECT UNTIL 6AM OVER THE
OPEN WATERS. WINDS MAY BRIEFLY SLACK DURING THE DAYTIME HOURS TODAY
BEFORE INCREASING BACK TO 15 TO 20 OVERNIGHT TONIGHT.  UNSETTLED
CONDITIONS WILL PREVAIL FROM SUNDAY NIGHT FORWARD WITH STRONG
NORTHERLY WINDS BEHIND THE COLD FRONT SUNDAY NIGHT INTO MONDAY.
SMALL CRAFT ADVISORIES POSSIBLE OVER ALL MARINE LOCATIONS LATE
SUNDAY INTO MONDAY.  SURFACE HIGH PRESSURE WILL BUILD IN TUESDAY
ALLOWING WINDS AND WAVES TO DECREASE.  HIGH PRESSURE WILL QUICKLY
SLIDE EAST ON WEDNESDAY AS SURFACE LOW TRACKS ALONG THE NORTHERN GULF
COAST.  A STRONGER EASTERLY FLOW WILL RESUME AS A RESULT ON
WEDNESDAY.

DECISION SUPPORT...
DSS CODE...BLUE.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...SLURRY SUPPORT
             SMALL CRAFT ADVISORY THIS MORNING

DECISION SUPPORT SERVICES (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 SEVERE; NEARBY
         TROPICAL EVENTS; HAZMAT OR OTHER LARGE EPISODES
RED    = FULL ENGAGEMENT FOR MODERATE TO HIGH RISK SVR
         AND/OR DIRECT TROPICAL THREATS; EVENTS OF NATIONAL
         SIGNIFICANCE.

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  61  50  68  40 /   0  30  70  60
BTR  62  51  70  42 /   0  30  60  50
ASD  61  52  71  45 /   0  20  60  50
MSY  62  56  73  48 /   0  20  60  50
GPT  59  51  68  45 /   0  20  60  50
PQL  60  49  69  46 /   0  10  70  50

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...NONE.
MS...NONE.
GM...NONE.
&&

$$







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