561
FXUS64 KLIX 100222
AFDLIX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
922 PM CDT TUE AUG 9 2022
UPDATE
MADE A FEW CHANGES TO THE FORECAST THIS EVENING AS A PERSISTENT
AREA OF SHOWERS AND THUNDERSTORMS HAS ENTERED THE FORECAST AREA
FROM THE NORTH AFFECTING THE NORTHWESTERN PORTIONS OF THE AREA.
INCREASED RAIN CHANCES THROUGH THE NEXT SEVERAL HOURS AND
REFRESHED THINGS A BIT AS WELL. WHILE THE AFOREMENTIONED SHOWERS
AND THUNDERSTORMS SEEM TO BE WANING A BIT OVERALL IN INTENSITY,
WILL BE MONITORING THE RAINFALL AMOUNTS AS THEY ARE MOVING FAIRLY
SLOWLY.
PREV DISCUSSION
/ISSUED 520 PM CDT TUE AUG 9 2022/
SHORT TERM...ACTIVE DAY TODAY BUT DIDN'T QUITE SEEM AS ACTIVE AS
YESTERDAY HOWEVER, STORMS MAY PERSIST LONGER INTO THE EVENING THAN
PREVIOUS DAYS AS WE SEEM TO BE IN MORE OF A TROPICAL LIKE
ENVIRONMENT LEADING TO AN INCREASE IN THE OCCURRENCE OF NOCTURNAL
CONVECTION. THIS NOCTURNAL CONVECTION USUALLY MEANS CONVECTION
CONTRACTS TOWARDS THE CENTER OF THE DISTURBANCE AND THAT COULD BE
WELL WHAT HAPPENS TONIGHT. THE TROPICAL WAVE LEADING TO OUR STORMS
IS NOW OVER COASTAL LA AND COASTAL MS WITH VERY BROAD ROTATION
NEAR THE BRETON AND CHANDELEUR SOUNDS. THIS COULD CAUSE CONVECTION
TO CONTRACT BACK CLOSER TOWARDS THE COAST OVERNIGHT AND COULD BE
HEAVY AT TIMES.
SO OVER THE NEXT 2 DAYS AND MAYBE EVEN FRIDAY WE WILL SEE ADDITIONAL
HEAVY RAIN BUT IT MAY BE A LITTLE MORE WIDESPREAD AS WE WILL HAVE
MULTIPLE FEATURES COMING TOGETHER. FIRST IS THE TROPICAL WAVE WE
ARE CURRENTLY BEING IMPACTED BY AND THE WEAKENING TUTT MOVING
ACROSS THE NORTHERN GULF. THE TUTT WILL BECOME LESS DEFINED OVER
THE NEXT 24 HRS AS THE NORTHERN STREAM L/W TROUGH DIGS ACROSS THE
APPALACHIANS AND A S/W UPSTREAM CONTINUES TO BREAK DOWN THE RIDGE
AND MOVE INTO THE LOWER MS VALLEY. THIS WILL LEAD TO A FULL BLOWN
TROUGH AXIS SETTING UP RIGHT ALONG THE WESTERN FRINGES OF OUR
CWA. THERE IS ANOTHER TROPICAL WAVE MOVING THROUGH THE WESTERN
CARIBBEAN AND IT APPEARS A PIECE OF IT BROKE OFF THE NORTHERN SIDE
AND SURGED NORTHWEST THROUGH THE FLORIDA STRAITS THIS MORNING AND
CONTINUED TO FLY ACROSS THE SOUTHEASTERN GULF. IF THERE IS STILL
ANYTHING LEFT TO THAT IT COULD JUST ADD MORE LIFT AND LOW LEVEL
MOISTURE TO THE AREA TOMORROW, LEADING TO BOTH WIDESPREAD
CONVECTION AND STRONGER MORE EFFICIENT STORMS. LUCKILY RAIN DID
NOT OVERACHIEVE OR AT LEAST WASN'T AS HEAVY WIDESPREAD. THAT SAID,
SOME LOCATIONS STILL SAW NEAR 4" AND THERE WAS FLOODING AROUND
HARAHAN. THIS IS ONLY AN EXAMPLE OF WHAT WE COULD SEE OVER THE
NEXT FEW DAYS AND POSSIBLY OVER A LARGER AREA. BACK TO THE
EFFICIENCY OF STORMS, PWS WILL MAY BE EVEN HIGHER TOMORROW WITH
MODELS SUGGESTING PWS POSSIBLY APPROACHING 2.5", AND H85 THETA E
AIR OF AROUND 340K MOVING INTO THE REGION. THE K INDEX COULD
RANGE FROM 35-40C AND WILL ALSO BE MOVING INTO THE AREA (VALUES
ABV 35 AND CLOSER TO 40 USUALLY INDICATE A HIGHER POTENTIAL FOR
HEAVY RAIN). INSTABILITY WILL BE IN PLACE AS WELL SO MORE
THUNDERSTORM THAN SHOWER WHICH WILL ALSO CONTRIBUTE TO THE HEAVY
RAIN THREAT.
NOW THERE ARE SOME NEGATIVES AND IT DOES LOOK LIKE THESE COULD BE
EASILY OVERCOME BUT IT STILL WILL HAVE SOME NEGATIVE INFLUENCE ON
HEAVY RAIN POTENTIAL. FIRST IS NO REAL STRONG SIGNAL OF LL
CONVERGENCE. YES LL MOISTURE WILL MOVE IN AND INCREASE BUT THERE IS
NOT A REAL STRONG DELINEATION AND JUST A GRADUAL INCREASE. (THE
LL CONVERGENCE ON THURSDAY THOUGH WILL BE IN PLACE). SECOND, THERE
ISN'T ANY STRONG SIGNAL OF UPPER LEVEL DIVERGENCE. LOOKING AT
SATELLITE THERE IS BETTER DIVERGENCE OVER THE CENTRAL AND EASTERN
GULF BUT IT DOENS'T LOOK LIKE THAT WILL MOVE NORTH, YET. BOTH OF
THESE ARE GENERALLY FEATURES THAT WILL ENHANCE THE HEAVY RAIN
POTENTIAL BUT GIVEN ALL OF THE OTHER FEATURES AND HOW EFFICIENT
RAIN HAS BEEN ALREADY SUGGESTS LOCALLY HEAVY RAIN IS LIKELY. AS
FOR A FLASH FLOOD WATCH WE WILL HOLD OFF RIGHT NOW MAINLY BECAUSE
WE LACKED WIDESPREAD HEAVY RAINFALL TODAY AND ALL OF THE RIVERS
ARE STILL FAIRLY LOW. THIS SHOULD PROVIDE ENOUGH STORAGE AND
POTENTIAL TO KEEP THINGS UNDER CONTROL FOR MOST OF THE AREA. NOW
UNDERSTAND THAT ANY OF THE POPULATION CENTERS IT DOESN'T MATTER IF
IT RAINED TODAY, LAST WEEK, OR LAST YEAR, IT ONLY TAKE THE RIGHT
STORM OR STORMS TO SIT OVER THESE AREAS JUST LONG ENOUGH TO
QUICKLY LEAD TO WATER COLLECTING AND FLOODING THE TYPICAL LOW
LYING AREAS.
THURSDAY IS STILL THE GREATEST CONCERN BECAUSE NOW IT LOOKS LIKE WE
WILL HAVE SOME LOW LEVEL SUPPORT/FOCUS AS A BOUNDARY THAT IS
CURRENTLY DRAPED ACROSS THE SOUTHERN PLAINS, MID MS VALLEY, AND OH
VALLEY GETS ANOTHER PUSH TOMORROW AND THURSDAY AND IS EXPECTED TO
MOVE INTO THE AREA. ALL OTHER INGREDIENTS WE HAVE IN PLACE
TOMORROW WILL STILL BE IN PLACE THURSDAY FOR THE MOST PART AND
EVEN THOUGH UPPER LEVEL DIVERGENCE ISN'T GREAT, THERE IS A HINT
IT COULD IMPROVE JUST ENOUGH AS OTHER UPPER LEVEL FEATURES MOVE
INTO PLACE AND JUST LEADING TO BETTER DIVERGENCE BY DEFAULT. THIS
WILL ONLY INCREASE THE RISK FOR HEAVY RAIN AND POSSIBLY MORE
WIDESPREAD. CAMS ARE STARTING TO FINALLY COME INTO THE TIME FRAME
AND ARE SHOWING THE POTENTIAL FOR HEAVY RAIN AS WELL. DON'T TAKE
THE LOCATION FOR GOSPEL HOWEVER LOOKING AT THE CAMS AS A BAROMETER
FOR POTENTIAL WIDESPREAD 2-4 INCHES WITH LOCALLY HIGHER VALUES
GREATER THAN 7 INCHES ARE BEING ADVERTISED OVER THE NEXT 48 HRS.
SO THE POTENTIAL IS THERE JUST NOT QUITE CONFIDENT ENOUGH OF A
LOCATION BUT IT APPEARS THE GREATEST THREAT FOR FLASH FLOODING
POTENTIAL WOULD BE SOUTH OF THE MS BORDER DOWN AND ALONG I-10 AND
EAST ACROSS COASTAL MS. THERE IS A GOOD CHANCE SOME BAND DEVELOPS
AND TRAINS OVER AN AREA ESPECIALLY THURSDAY AND WHERE THAT OCCURS
WILL LIKELY HAVE THE GREATEST IMPACT. IF WE GET A LARGE AREA OF
HEAVY RAIN TOMORROW THEN WE WILL LIKELY NEED A FLASH FLOOD WATCH
FOR PORTIONS OF THE AREA THURSDAY, MAYBE AS EARLY AS WEDNESDAY
NIGHT.
FRIDAY MODELS HAVE EVOLVED A LITTLE NOW INDICATING THAT THE RIDGE
WILL WILL BEGIN TO PINCH THE BOTTOM OF THE L/W TROUGH AND COULD
BREAK OFF A PIECE AT THE BASE LEADING TO A MID LEVEL CUTOFF LOW OR
ANOTHER TUTT SITTING OVER THE AREA FRIDAY. THAT WOULD STILL INDICATE
NUMEROUS SHOWERS AND THUNDERSTORMS MOST OF THE DAY BUT THE OLD
BOUNDARY WILL CONTINUE TO SLOWLY WORK SOUTH AS IT TRIES TO MODIFY.
DUE TO THE SLOWER MOVEMENT WE WOULDN'T LIKELY SEE A MORE PRONOUNCED
AIRMASS SHIFT TILL THIS WEEKEND. /CAB/
LONG TERM...
MEDIUM RANGE GUIDANCE AGREE THAT BY SATURDAY, THE TUTT LOW WOULD BE
OUT OF THE AREA AND INTO TEXAS. THIS WOULD GIVE WAY TO NORTHERLY MID
TO UPPER LEVEL FLOW GIVEN THE POSITION OF THE H5 RIDGE OVER THE
CENTRAL PLAINS. GENERALLY, WITH THE NORTHERLY FLOW, THIS WILL BRING
DRIER AIR INTO THE MID AND UPPER LEVELS, CAUSING STORM DEVELOPMENT
TO BE LATER IN THE AFTERNOON. THIS WILL ALLOW MORE DAYTIME HEATING
AND A RISE IN MAXIMUM TEMPERATURES EACH DAY. ON THE OTHER HAND, THE
HEATING WILL ALSO INCREASE INSTABILITY. SINCE THE MID LEVEL DRY AIR
WILL BE IN PLACE, THE STRONGER STORMS COULD POSE A GUSTY WIND
THREAT.
SOME OF THE MEDIUM RANGE MODELS HINT AT A MID LEVEL DISTURBANCE IN
THE H5 FLOW AROUND THE PERIPHERY OF THE RIDGE AND INTO OUR AREA
AROUND THE SATURDAY INTO SUNDAY TIMEFRAME. SURFACE TROUGHING SEEMS
TO SET UP BECAUSE OF THIS AND THE AFOREMENTIONED TROUGH COULD SERVE
AS A FOCUS FOR RAINFALL. CONFIDENCE IS NOT HIGH WHEN THIS WILL OCCUR
BECAUSE OF THE DIFFERENCES IN TIMING AS SOLUTIONS VARY BETWEEN THIS
OCCURRING ANYWHERE BETWEEN SATURDAY AND SUNDAY. REGARDLESS, WE WILL
RETURN TO NORTHERLY FLOW THEREAFTER AS THE MODELS AGREE THAT THE
RIDGE'S POSITION WILL STAY THE SAME. /JMZ/
AVIATION...
18Z TAF PACKAGE...CONVECTION IS THE GREATEST IMPACT
THROUGH THE AFTERNOON AND EARLY EVENING. SOME LOW CIGS ARE
IMPACTING TERMINALS OFF AND ON LEADING TO TEMPO MVFR CIGS BUT
OVERALL AS LONG AS THESE SITES REMAIN CONVECTION FREE THEY SHOULD
REMAIN IN VFR STATUS. AFTER CONVECTION WINDS DOWN ALL TERMINALS
WILL MOVE BACK INTO VFR STATUS IF NOT ALREADY THERE BUT AROUND
9/10Z WE COULD SEE THE SAME ISSUES WE HAVE BEEN FOR THE LAST FEW
DAYS WITH IFR AND POSSIBLY LIFR CIGS ALONG WITH PATCHY IFR VSBYS.
THE MOST LIKELY TIME TO SEE THESE IMPACTS WILL BE FROM 9-13Z AND
PROBABLY OVER THE SAME LOCATIONS LIKE MCB AND BTR. /CAB/
MARINE...
PERSISTENT ONSHORE FLOW WILL CONTINUE INTO TOMORROW. BY
TOMORROW AND WEDNESDAY NIGHT, A WEAK LOW PRESSURE SYSTEM IN THE
CENTRAL GULF COULD PUSH WINDS AND SEAS HIGHER. THIS LOW WILL TRACK
INTO TEXAS BY FRIDAY, AND WINDS ARE EXPECTED TO DROP BACK TO 10
KNOTS OR LESS. ADDITIONALLY, WINDS AND SEAS WILL BE HIGHER NEAR
ANY THUNDERSTORM ACTIVITY THAT DEVELOPS TODAY AND THAT ALSO
INCLUDES THE POSSIBILITY OF WATERSPOUTS.
TIDES WILL BE A PROBLEM THROUGH OUT THE WEEK. THE SOUTHEASTERLY
WINDS WILL BE IN PLACE ACROSS MUCH OF THE GULF AND THIS WILL OCCUR
IN COMBINATION WITH THE SPRING TIDE. THIS WILL CAUSE SOME TIDAL
ISSUES IN THE KNOWN TROUBLE SPOTS AND A COASTAL FLOOD ADVISORY
REMAINS IN EFFECT THROUGH MIDDAY THURSDAY.
PRELIMINARY POINT TEMPS/POPS
MCB 70 86 70 86 / 30 90 30 90
BTR 73 89 73 87 / 50 90 20 90
ASD 74 88 73 87 / 10 90 40 90
MSY 76 87 76 87 / 10 90 30 90
GPT 75 87 74 87 / 20 90 50 90
PQL 74 87 73 87 / 20 90 50 90
LIX WATCHES/WARNINGS/ADVISORIES
LA...COASTAL FLOOD ADVISORY UNTIL 1 PM CDT THURSDAY FOR LAZ066>070-
076-078.
GM...NONE.
MS...COASTAL FLOOD ADVISORY UNTIL 1 PM CDT THURSDAY FOR MSZ080>082.
GM...NONE.
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