Post by SKYSUMMIT on Dec 26, 2014 16:18:48 GMT -6
NEW ORLEANS:
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
417 PM CST FRI DEC 26 2014
...HEAVY RAIN LOOKS TO IMPACT THE REGION THIS WEEKEND...
.SHORT TERM...MAJORITY OF THE FCST CONCERNS RESIDE IN THE FIRST 60
HRS OF THE FCST. AS FOR TODAY IT HAS BEEN A CLOUDY AND COOL DAY.
TEMPS HAVE STRUGGLED TO GET MUCH ABV THE LOWER-MID 60S WITH THE
EXTREME NW PORTIONS OF THE CWA STRUGGLING TO GET INTO THE 60S.
L/W TROUGH OVER THE WRN CONUS HAS PLACED THE AREA UNDER DEEP SWRLY
FLOW THIS IS BOTH GREATLY INCREASING THE MOISTURE IN THE MID AND
UPPER LVLS ALONG WITH INCREASING THE LIFT OVER THE REGION. AT THE
SFC HIGH PRESSURE OVER THE PIEDMONT/TOBACCO ROAD REGION IS LEADING
TO SRLY FLOW IN THE LL WHICH IS HELPING TO PUMP IN THE GULF
MOISTURE. BOTH OF THESE WILL HELP TO CONTRIBUTE TO PWS SUBSTANTIALLY
INCREASING...APPROACHING 2 INCHES WHICH IS ALMOST 225% OF NORMAL AND
IN THE 99TH PERCENTILE FOR MOISTURE CONTENT IN OUR AREA DURING
DECEMBER. THAT ALONE IS A RED FLAG. BEGINNING TONIGHT ESPECIALLY
AFTER 6Z ISENTROPIC LIFT WILL INCREASE ACROSS THE REGION AND IN THE
290-295K LVL THE ISENTROPIC LIFT BECOMES QUITE STRONG ACROSS MUCH OF
SELA AND SWRN MS BUT ESPECIALLY OVER THE FLORIDA PARISHES DURING THE
AFTN AND EVNG TOMORROW. DIVERGENCE ALOFT WILL ALSO INCREASE
TOMORROW. COMBINE THAT WITH A WEAK SFC BNDRY DRAPED ACROSS THE
REGION AND THE INGREDIENTS ARE BEGINNING LINE UP FOR A RATHER WET
SCENARIO WITH HEAVY RAIN BEGINNING TOMORROW AND PERSISTING THROUGH
SAT NIGHT.
THE OTHER CONCERN SAT AND SAT NIGHT IS INSTABILITY. MDLS SHOW AMPLE
ELEVATED INSTABILITY AND EVEN A LITTLE SFC BASED INSTABILITY AND THIS
WILL LEAD TO SCT TO NUM TSRA SAT AND INTO SAT EVNG. WITH THE MOISTURE
WE ARE ANTICIPATING...COMBINED WITH DIVERGENCE ALOFT AND DECENT
INSTABILITY...TSRA WILL BE RATHER EFFICIENT AND COULD DROP QUITE A
BIT OF RAINFALL IN A SHORT TIME. ISLTD TSRA COULD BEGIN AS EARLY AS
THE OVERNIGHT HRS TONIGHT BUT WE REALLY EXPECT THEM TO PICK UP
DURING THE DAY TOMORROW ESPECIALLY AFTER 15Z.
SW FLOW ALOFT WILL CONTINUE THROUGH SUN WITH VERY DEEP MOISTURE
STILL IN PLACE AND THUS THE HEAVY RAIN POTENTIAL WILL CONTINUE WHICH
WILL ONLY EXACERBATE ANY ISSUES THAT WE ALREADY HAVE. A COLD FRONT
WILL FINALLY PUSH THROUGH THE REGION SUN NIGHT EARLY MON MORNING AND
THIS SHOULD FINALLY BRING AN END TO THE RAIN THREAT. NOT
ANTICIPATING NEARLY AS MUCH IN THE WAY OF TSRA SUN AS INSTABILITY IS
GREATLY REDUCED AS THE SNDGS SHOW A RAIN LOADED PROFILE WITH MID LVL
LAPSE RATES ACTUALLY SUPER ADIABATIC. MODERATE TO HEAVY SHRA WILL
STILL BE POSSIBLE THROUGH THE DAY SUN BUT THINGS SHOULD REALLY BEGIN
TO SLACK OFF OVERNIGHT SUN AFTER A STRONG SW MOVES THROUGH THE FLOW
AND ACROSS THE LOWER MS VALLEY DURING THE EVNG HRS ALONG WITH THE
FRONTAL PASSAGE OVERNIGHT.
AFTER EVERYTHING IS SAID AND DONE THERE IS THE POTENTIAL FOR
WIDESPREAD 3-5 INCHES OF RAIN WITH LOCALLY HIGHER AMOUNTS POSSIBLY
RANGING FROM 6 TO AS MUCH AS 10 INCHES. DONT FEEL COMPLETELY
COMFORTABLE TRYING TO PINPOINT A LOCATION TO WHERE THE HEAVIEST RAIN
WILL OCCUR AS IT ONLY TAKES A SMALL SHIFT IN THINGS TO HAVE A 20 TO
60 MILE DIFFERENCE IN PLACEMENT BUT IF I HAD TO CHOOSE A LOCATION I
WOULD BE CONCERNED WITH THE FLORIDA PARISHES AND AROUND THE BATON
ROUGE METRO AND TWRDS THE MCCOMB AREA.
FLOOD WATCH REMAINS OUT FOR THE REGION THROUGH 00Z MON AND SEE NO
REASON CHANGING IT IN TIME OR LOCATION AT THIS TIME. MAY NEED TO
CHANGE IT TO A FLASH FLOOD WATCH BUT THE INITIAL FEELING IS THIS
WOULD BE A MORE PROLONGED EVENT LEADING TO MORE OF A RIVER ISSUE
THREAT AND SOME OF THE LOW LYING/ROUGH DRAINING AREAS BUT IF MDLS
CONTINUE TO RAMP THINGS UP WITH MOST OF THE HEAVY RAIN SAT AND SAT
NIGHT FLASH FLOODING WILL BE A CONCERN.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
417 PM CST FRI DEC 26 2014
...HEAVY RAIN LOOKS TO IMPACT THE REGION THIS WEEKEND...
.SHORT TERM...MAJORITY OF THE FCST CONCERNS RESIDE IN THE FIRST 60
HRS OF THE FCST. AS FOR TODAY IT HAS BEEN A CLOUDY AND COOL DAY.
TEMPS HAVE STRUGGLED TO GET MUCH ABV THE LOWER-MID 60S WITH THE
EXTREME NW PORTIONS OF THE CWA STRUGGLING TO GET INTO THE 60S.
L/W TROUGH OVER THE WRN CONUS HAS PLACED THE AREA UNDER DEEP SWRLY
FLOW THIS IS BOTH GREATLY INCREASING THE MOISTURE IN THE MID AND
UPPER LVLS ALONG WITH INCREASING THE LIFT OVER THE REGION. AT THE
SFC HIGH PRESSURE OVER THE PIEDMONT/TOBACCO ROAD REGION IS LEADING
TO SRLY FLOW IN THE LL WHICH IS HELPING TO PUMP IN THE GULF
MOISTURE. BOTH OF THESE WILL HELP TO CONTRIBUTE TO PWS SUBSTANTIALLY
INCREASING...APPROACHING 2 INCHES WHICH IS ALMOST 225% OF NORMAL AND
IN THE 99TH PERCENTILE FOR MOISTURE CONTENT IN OUR AREA DURING
DECEMBER. THAT ALONE IS A RED FLAG. BEGINNING TONIGHT ESPECIALLY
AFTER 6Z ISENTROPIC LIFT WILL INCREASE ACROSS THE REGION AND IN THE
290-295K LVL THE ISENTROPIC LIFT BECOMES QUITE STRONG ACROSS MUCH OF
SELA AND SWRN MS BUT ESPECIALLY OVER THE FLORIDA PARISHES DURING THE
AFTN AND EVNG TOMORROW. DIVERGENCE ALOFT WILL ALSO INCREASE
TOMORROW. COMBINE THAT WITH A WEAK SFC BNDRY DRAPED ACROSS THE
REGION AND THE INGREDIENTS ARE BEGINNING LINE UP FOR A RATHER WET
SCENARIO WITH HEAVY RAIN BEGINNING TOMORROW AND PERSISTING THROUGH
SAT NIGHT.
THE OTHER CONCERN SAT AND SAT NIGHT IS INSTABILITY. MDLS SHOW AMPLE
ELEVATED INSTABILITY AND EVEN A LITTLE SFC BASED INSTABILITY AND THIS
WILL LEAD TO SCT TO NUM TSRA SAT AND INTO SAT EVNG. WITH THE MOISTURE
WE ARE ANTICIPATING...COMBINED WITH DIVERGENCE ALOFT AND DECENT
INSTABILITY...TSRA WILL BE RATHER EFFICIENT AND COULD DROP QUITE A
BIT OF RAINFALL IN A SHORT TIME. ISLTD TSRA COULD BEGIN AS EARLY AS
THE OVERNIGHT HRS TONIGHT BUT WE REALLY EXPECT THEM TO PICK UP
DURING THE DAY TOMORROW ESPECIALLY AFTER 15Z.
SW FLOW ALOFT WILL CONTINUE THROUGH SUN WITH VERY DEEP MOISTURE
STILL IN PLACE AND THUS THE HEAVY RAIN POTENTIAL WILL CONTINUE WHICH
WILL ONLY EXACERBATE ANY ISSUES THAT WE ALREADY HAVE. A COLD FRONT
WILL FINALLY PUSH THROUGH THE REGION SUN NIGHT EARLY MON MORNING AND
THIS SHOULD FINALLY BRING AN END TO THE RAIN THREAT. NOT
ANTICIPATING NEARLY AS MUCH IN THE WAY OF TSRA SUN AS INSTABILITY IS
GREATLY REDUCED AS THE SNDGS SHOW A RAIN LOADED PROFILE WITH MID LVL
LAPSE RATES ACTUALLY SUPER ADIABATIC. MODERATE TO HEAVY SHRA WILL
STILL BE POSSIBLE THROUGH THE DAY SUN BUT THINGS SHOULD REALLY BEGIN
TO SLACK OFF OVERNIGHT SUN AFTER A STRONG SW MOVES THROUGH THE FLOW
AND ACROSS THE LOWER MS VALLEY DURING THE EVNG HRS ALONG WITH THE
FRONTAL PASSAGE OVERNIGHT.
AFTER EVERYTHING IS SAID AND DONE THERE IS THE POTENTIAL FOR
WIDESPREAD 3-5 INCHES OF RAIN WITH LOCALLY HIGHER AMOUNTS POSSIBLY
RANGING FROM 6 TO AS MUCH AS 10 INCHES. DONT FEEL COMPLETELY
COMFORTABLE TRYING TO PINPOINT A LOCATION TO WHERE THE HEAVIEST RAIN
WILL OCCUR AS IT ONLY TAKES A SMALL SHIFT IN THINGS TO HAVE A 20 TO
60 MILE DIFFERENCE IN PLACEMENT BUT IF I HAD TO CHOOSE A LOCATION I
WOULD BE CONCERNED WITH THE FLORIDA PARISHES AND AROUND THE BATON
ROUGE METRO AND TWRDS THE MCCOMB AREA.
FLOOD WATCH REMAINS OUT FOR THE REGION THROUGH 00Z MON AND SEE NO
REASON CHANGING IT IN TIME OR LOCATION AT THIS TIME. MAY NEED TO
CHANGE IT TO A FLASH FLOOD WATCH BUT THE INITIAL FEELING IS THIS
WOULD BE A MORE PROLONGED EVENT LEADING TO MORE OF A RIVER ISSUE
THREAT AND SOME OF THE LOW LYING/ROUGH DRAINING AREAS BUT IF MDLS
CONTINUE TO RAMP THINGS UP WITH MOST OF THE HEAVY RAIN SAT AND SAT
NIGHT FLASH FLOODING WILL BE A CONCERN.
