FXUS64 KLIX 280122
AFDLIX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
722 PM CST FRI NOV 27 2009
.UPDATE...
...SOUNDING DISCUSSION...
NO PROBLEMS WITH THE FLIGHT THIS EVENING. THE SOUNDING SHOWS THAT
THE ATMOSPHERE REMAINS EXTREMELY DRY AND STABLE...ALTHOUGH PW
VALUES HAVE COME UP SLIGHTLY TO AROUND 0.3 INCHES. THE INCREASED
MOISTURE IS MOSTLY ABOVE 25K FEET WITH HIGH CLOUDS STREAMING
ACROSS THE AREA FROM THE WEST. WINDS REMAIN LIGHT NEAR THE SURFACE
AND ARE OUT OF THE WEST ALOFT.
98/SO
&&
.PREV DISCUSSION... /ISSUED 233 PM CST FRI NOV 27 2009/
SYNOPSIS...
SURFACE HIGH PRESSURE IS CENTERED OVER THE AREA. SCATTERED TO
BROKEN HIGH CLOUDS HAVE HELPED KEEP AFTERNOON TEMPERATURES RIGHT
AROUND 60 DEGREES. DRY AIR ALOFT HAS MIXED DOWN TO THE SURFACE IN
MANY PLACES AND DEWPOINTS ARE GENERALLY IN THE UPPER 20S AND LOWER
30S. UPPER TROUGH IS DIGGING SOUTHWARD ALONG THE PACIFIC COAST
WITH A BAROCLINIC LEAF CLOUD PATTERN DEVELOPING JUST WEST OF THE
ROCKIES.
SHORT TERM...
WARMING TREND SHOULD BEGIN LATE TONIGHT OR SATURDAY AS THE HIGH
CONTINUES TO SHIFT EASTWARD. THIS WILL CAUSE WINDS TO BECOME MORE
SOUTHEASTERLY AND WILL RESULT IN THE TRANSPORT OF WARM MOIST AIR
INTO THE AREA FROM THE GULF OF MEXICO. OVERNIGHT LOWS TONIGHT
SHOULD BE 5 TO 10 DEGREES WARMER THAN LAST NIGHT ACROSS THE
WESTERN HALF OF THE AREA AND 3 TO 5 DEGREES WARMER THAN LAST NIGHT
ACROSS THE EASTERN HALF. EXPECT HIGHS IN THE MID 60S FOR
SATURDAY...WHICH IS JUST ABOUT NORMAL FOR THIS TIME OF YEAR.
WARMING TREND CONTINUES INTO SUNDAY WITH OVERNIGHT LOWS FORECAST
TO INCREASE BY ANOTHER 10 DEGREES COMPARED TO TONIGHT. HIGHS WILL
ALSO INCREASE INTO THE LOW TO MID 70S.
ELSEWHERE IN THE COUNTRY...THE UPPER TROUGH CURRENTLY LOCATED
NEAR THE WEST COAST WILL MOVE EASTWARD DIGGING INTO THE ROCKY
MOUNTAINS REGION. AS IT DOES SO...A CLOSED UPPER LOW IS FORECAST
TO DEVELOP AT THE BASE OF THE TROUGH. THE NORTHERN STREAM TROUGH
WILL CONTINUE EASTWARD FORCING A COLD FRONT TOWARD THE AREA ON
SUNDAY WHILE THE SOUTHERN STREAM LOW LAGS BEHIND OVER THE
SOUTHWEST CONUS. THIS CUT OFF LOW WILL THEN SERVE TO SLOW THE
PROGRESSION OF THE COLD FRONT AS IT MOVES INTO AND THROUGH THE
AREA.
LONG TERM...
IT LOOKS LIKE A WET START TO THE WORK WEEK. SHOWERS AND A FEW
THUNDERSTORMS ARE EXPECTED TO ACCOMPANY THE FRONT AS IT MOVES
SLOWLY THROUGH THE AREA SUNDAY NIGHT THROUGH MONDAY NIGHT. IN
ADDITION TO THE ELEVATED POPS...LOCALLY HEAVY RAINFALL MAY BECOME
A PROBLEM IN SOME LOWER LYING AREAS DUE TO THE SLOW MOVING NATURE
OF THE FRONT. THIS WILL BE ESPECIALLY TRUE FOR THE SOUTHERN HALF
OF THE FORECAST AREA...WHERE THE SLOWING/STALLED BOUNDARY WILL
CONTINUE TO PROVIDE A FOCUS FOR SHOWER AND THUNDERSTORM
DEVELOPMENT. GENERALLY CARRYING BETWEEN 1 AND 1.5 INCHES OF
RAINFALL ACROSS THE AREA AS THE FRONT MOVES THROUGH.
A SURFACE LOW IS FORECAST TO DEVELOP ALONG THE STALLED BOUNDARY
OVER THE WESTERN GULF ON TUESDAY AS THE CLOSED UPPER LOW
BEGINS TO MOVE EASTWARD TOWARD THE LOCAL AREA. THE MODELS ARE IN
GOOD AGREEMENT CONCERNING THE DEVELOPMENT OF THIS LOW...BUT
CONTINUE TO SHOW VARIED SOLUTIONS CONCERNING THE TRACK OF THE
LOW. THE GFS CONTINUES TO FORECAST A MORE SOUTHERLY TRACK WITH THE
LOW MOVING INTO THE FLORIDA PANHANDLE THEN HEADING TOWARD SAVANNAH
GEORGIA AND UP THE EAST COAST. THE ECMWF CONTINUES TO FORECAST A
MORE NORTHERLY TRACK WITH THE LOW MOVING INLAND OVER COASTAL
MISSISSIPPI AND TAKING THE FAST TRACK TO NEW ENGLAND. BOTH OF
THESE SOLUTIONS SEEM REASONABLE...SO WILL CONTINUE TO USE A BLEND
OF THE TWO.
WET CONDITIONS WILL CONTINUE INTO MIDWEEK AS THIS NEW LOW MOVES
NORTHEASTWARD THROUGH THE AREA. MODELS CONTINUE TO FORECAST AN
ADDITIONAL 4 TO 5 INCHES OF RAIN AS THE LOW MOVES PAST THE AREA
TUESDAY AND TUESDAY NIGHT. MOST OF THIS RAIN IS CURRENTLY FORECAST
TO REMAIN OFFSHORE. HOWEVER...IF THE TRACK OF THE LOW SHIFTS
NORTHWARD...WHICH IS ENTIRELY POSSIBLE...THE BROAD AREA OF HEAVY
RAIN WILL ALSO SHIFT NORTHWARD. THE AREAS MOST AT RISK FOR HEAVY
RAIN WILL BE THOSE THAT ARE GENERALLY SOUTH OF LAKE PONTCHARTRAIN
OR ALONG THE MISSISSIPPI GULF COAST.
AN ADDITIONAL CONCERN WILL BE STRONG TO SEVERE THUNDERSTORMS. WITH
THE CURRENT FORECAST...ANY STRONG THUNDERSTORMS WILL BE LIMITED TO
THE GULF COASTAL WATERS. HOWEVER...IF THE LOW SHIFTS NORTHWARD...
SOME LAND AREAS WILL FIND THEMSELVES IN THE WARM SECTOR WITH
STRONG THUNDERSTORMS POSSIBLE. AGAIN...THE AREA WITH THE HIGHEST
RISK WILL BE THOSE THAT ARE SOUTH OF THE TIDAL LAKES OR ALONG THE
MISSISSIPPI GULF COAST. WE WILL CONTINUE TO MONITOR THE SITUATION
AND FUTURE FORECASTS WILL CONTINUE TO REFINE THE DETAILS OF THIS
SYSTEM. EITHER WAY THOUGH...PLAN ON CARRYING AN UMBRELLA THROUGH
THE FIRST HALF OF THE WORK WEEK.
ONCE THE LOW MOVES OUT OF THE AREA...DRY HIGH PRESSURE WILL BUILD
INTO THE AREA ENDING RAIN CHANCES THROUGH THE REMAINDER OF THE
WEEK.
AVIATION...
CIRRUS CLOUDS WILL CONTINUE ACROSS THE AREA THROUGH THE FORECAST
PERIOD. EXPECT VFR CONDITIONS THROUGHOUT THE PERIOD...BUT CEILINGS
BELOW 10K FEET BECOME MORE LIKELY BY MIDDAY SATURDAY.
MARINE...
RELATIVELY LOW WINDS AND SEAS ARE EXPECTED THROUGH THE WEEKEND
BEFORE INCREASING WITH ADVANCE AND PASSAGE OF NEXT COLD FRONT MONDAY
NIGHT. NORTH WINDS SHOULD REMAIN STRONG TUESDAY AND MAY BECOME
ENHANCED FURTHER IF LOW PRESSURE INDICATED IN MODELS DEVELOP IN THE
WEST GULF DURING THE MID TO LATTER PART OF NEXT WEEK.
CURRENTLY...WIND FORECAST FOR THE EARLY AND MIDDLE PART OF NEXT WEEK
IS BASED ON GFS SOLUTION WHICH HAS REASONABLE CONTINUITY FOR THE
LAST 24 HOURS.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 37 65 47 72 / 0 0 10 20
BTR 40 67 50 73 / 0 0 10 20
MSY 44 66 54 73 / 0 0 10 20
GPT 37 65 49 71 / 0 0 10 10
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
GM...NONE.
MS...NONE.
GM...NONE.
&&
$$
