306  
FXUS62 KJAX 200707  
AFDJAX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE JACKSONVILLE FL  
307 AM EDT WED SEP 20 2017  
 
...MINOR FLOODING CONTINUES ON THE ST JOHNS RIVER BASIN DURING  
TIMES OF HIGH TIDE...  
   
NEAR TERM /TODAY-TONIGHT/
 
 
TODAY...WEAK TROF ALOFT WILL PUSH INTO SE GA TODAY WITH A SLIGHT  
INCREASE IN MOISTURE WITH PWATS AROUND 1.8" AND THIS COMBINED WITH  
DAYTIME HEATING SHOULD BE ENOUGH TO TRIGGER WIDELY SCATTERED  
SHOWERS AND STORMS BY THE AFTERNOON HOURS. MOST OF THIS ACTIVITY  
WILL BE NW OF A LINE FROM JAX-GNV ACROSS SE GA, WHILE ACROSS THE  
REST OF NE FL CONDITIONS SHOULD REMAIN DRY WITH DRIER AIRMASS WITH  
PWATS OF 1.5" OR LESS. A FEW STORMS MAY CONTAIN SOME BRIEF HEAVY  
RAINFALL AND GUSTY WINDS BUT SEVERE WEATHER NOT EXPECTED. MAX  
TEMPS WILL REMAIN ABOVE NORMAL WITH LOWER 90S EXPECTED INLAND AND  
MID TO UPPER 80S ALONG THE COAST.  
 
TONIGHT...A FEW INLAND WIDELY SCATTERED SHOWERS/STORMS IN THE  
EVENING THAT SHOULD FADE BETWEEN SUNSET AND MIDNIGHT WITH JUST  
FAIR SKIES DURING THE OVERNIGHT HOURS AS WEAK TROF ALOFT LINGERS  
OVER THE REGION. MIN TEMPS A BIT MILDER OVERNIGHT WITH LOWS NEAR  
70 INLAND AND LOWER/MIDDLE 70S AT THE COAST.  
   
SHORT TERM...(THURSDAY THROUGH FRIDAY)
 
 
THURSDAY AND THURSDAY NIGHT...WEAK UPPER LEVEL TROUGHING WILL  
RESIDE OVER THE REGION. WITH IN THE BASE OF THE TROUGH, THERE  
WILL BE A WEAK IMPULSE THAT WILL TRACK OVER INTERIOR SE GA WHILE  
AT THE SAME TIME THERE WILL BE SURFACE BASED CONVERGENCE NEAR THE  
ALTAMAHA DURING THE MORNING THAT WILL SHIFT SOUTHWARD INTO THE  
SUWANNEE RIVER VALLEY. THERE WILL BE DEEP LAYER MOISTURE LOCATED  
NEAR THE SURFACE BASED CONVERGENCE (BETWEEN 1.75 TO 1.85") WITH  
SOME MID LEVEL INSTABILITY. THERE WILL BE A CHANCE OF SHOWERS AND  
FEW STORMS NORTH OF I-10 AND WEST OF 301 INTO INLAND SOUTHEAST  
GEORGIA. ISOLATED MAINLY SHOWERS AND STORMS THURSDAY EVENING  
SHOULD DISSIPATE AFTER MIDNIGHT. SOME ISOLATED COASTAL SHOWERS  
ALSO POSSIBLE AS MEAN HIGH PRESSURE RIDGE BUILDS NORTH OF THE AREA  
AS A PREVAILING EASTERLY FLOW DEVELOPS. MAX TEMPS ONCE AGAIN  
WARMER THAN NORMAL AROUND UPPER 80S TO ABOUT 90. LOWS WILL BE IN  
THE UPPER 60S TO LOWER 70S INLAND TO MID 70S ALONG THE COAST.  
 
FRIDAY...FULL ATTENTION WILL BE ON HURRICANE MARIA FORECAST BY  
NHC TO BE NEAR THE SOUTHEAST BAHAMAS FRI. SURFACE HIGH PRESSURE  
WILL RESIDE OVER THE WESTERN CAROLINAS, EAST TN, AND N GA. THIS  
WILL STRENGTHEN THE LOCAL GRADIENT ALONG THE BEACHES AND ADJACENT  
ATLANTIC WITH EASTERLY WINDS OF 12 TO 17 KNOTS WITH SOME GUSTS OF  
19 TO 23 KNOTS. THERE WILL BE A WEAK COASTAL TROUGH NEAR PALM  
COAST. THIS WEAK COASTAL TROF IN CONCERT WITH EASTERLY FLOW SHOULD  
INCREASE SOME AND PROVIDE ENOUGH MOISTURE TO PRODUCE SHOWERY  
PRECIP FRIDAY MAINLY SOUTH OF LINE FROM SAINT AUGUSTINE TO OCALA  
WITH ISOLATED THUNDER. MARKEDLY LESS TO NIL PRECIP COVERAGE NORTH  
OF THE AFOREMENTIONED LINE WHERE THERE IS BASICALLY LITTLE TO NO  
LOW LEVEL FORCING.  
   
LONG TERM...(SATURDAY THROUGH TUESDAY)
 
 
THE GENERAL SYNOPTIC PATTERN IS FOCUSED ON HURRICANE MARIA WHICH  
IS STILL PROJECTED TO MOVE NORTHWARD ROUGHLY BETWEEN 72W AND 73W  
SATURDAY AND SUNDAY. THIS WILL TRANSLATE INTO LOW LEVEL FLOW  
BACKING SLOWLY FROM EAST TO NORTHEAST AND HELP SHUNT DEEP MOISTURE  
SOUTH OF THE AREA. WE STILL ARE GOING WITH SCATTERED COVERAGE FOR  
SATURDAY WITH PRECIPITABLE WATER VALUES BETWEEN 1.85 AND 2 INCHES  
WITH A SURFACE BASED TROF OVER THE REGION PROVIDING CONVERGENCE.  
DRIER AIR SHOULD WORK IN FROM THE NORTHEAST AND NORTH ON SUNDAY  
AND WE BRING POPS DOWN TO 10-15 PERCENT. TEMPS WILL TREND MORE TO  
THE MID TO UPPER 80S DURING THE WEEKEND. BREEZY NORTHEASTERLY FLOW  
EXPECTED NEAR 15G25 MPH AT TIMES...MAINLY COASTAL COUNTIES AGAIN.  
MAIN CONCERN IS HIGH POTENTIAL FOR ROUGH SURF, BEACH EROSION, AND  
RIP CURRENT THREATS AT AREA BEACHES. THOUGH THERE IS FAIRLY GOOD  
AGREEMENT IN MODEL GUIDANCE ON MARIA NOT DIRECTLY AFFECTING FL,  
ALL INTERESTS SHOULD CONTINUE TO MONITOR THE PROGRESS OF MARIA  
THROUGH THE UPCOMING WEEK VIA THE LATEST ADVISORIES BEING ISSUED  
BY THE NATIONAL HURRICANE CENTER.  
 
SUBSIDENT AND DRY AIR-MASS CONTINUES MONDAY AND TUESDAY...WITH  
PWATS DROPPING TO OR BELOW 1.4 INCHES. SFC HIGH PRESSURE EXPECTED  
TO BE LOCATED OVER THE TN VALLEY AREA...WHILE HURRICANE MARIA IS  
FORECAST TO BE ABOUT 500-600 MILES EAST OF THE AREA. THE DRY AIR  
AND SOMEWHAT LIGHTER FLOW MAY BEGIN A TREND OF SLIGHTLY WARMER  
AFTN TEMPS COMPARED TO THE WEEKEND. PRIMARY CONCERN STILL IS  
CENTERED AROUND BEACH IMPACTS (IE, ROUGH SURF, SOME BEACH EROSION,  
AND HIGH RISK OF RIP CURRENTS) FOR EARLY NEXT WEEK WITH GUIDANCE  
SUGGESTING EAST-NORTHEAST SWELLS CONTINUING.  
 

 
   
AVIATION
 
 
VFR EXPECTED. RAIN CHANCES THIS AFTERNOON TOO LOW AT TAF SITES TO  
INCLUDE AT THIS POINT.  
 

 
   
MARINE
 
 
WILL ALLOW SMALL CRAFT ADVISORY TO EXPIRE AS SWELLS OVER THE  
OFFSHORE WATERS HAVE SUBSIDED TO 4-6 FEET AND WILL JUST GO WITH  
SCEC HEADLINE AS WINDS REMAIN VARIABLE 10 KNOTS OR LESS TODAY AND  
TONIGHT. WINDS BECOME E/NE ON THURSDAY AND SLOWLY INCREASE FRIDAY  
THROUGH THE WEEKEND AS TC MARIA PASSES WELL OFFSHORE ALTHOUGH SEAS  
WILL BUILD AS HIGH AS 10-15 FT OFFSHORE AND SMALL CRAFT ADVISORIES  
WILL NEED TO BE POSTED.  
 
RIP CURRENTS: MODERATE RISK CONTINUES IN LINGERING LONG PERIOD  
SWELLS AT THE COAST WITH SURF IN THE 2-4 FT RANGE WITH A FEW  
BREAKERS TO 5 FEET AT TIMES.  
 

 
   
HYDROLOGY
 
 
SANTA FE AND ST. MARYS RIVER FLOODING SLOWLY IMPROVING TO  
MODERATE LEVELS WHILE MINOR FLOODING CONTINUES ON THE SATILLA  
RIVER BASIN IN SE GA.  
 
COASTAL FLOOD ADVISORY REMAINS IN EFFECT FOR THE ST. JOHNS RIVER  
BASIN AS MINOR FLOODING CONTINUES DURING EACH HIGH TIDE CYCLE FROM  
JACKSONVILLE SOUTHWARD INTO PUTNAM COUNTY.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
AMG 92 70 90 69 / 30 10 30 10  
SSI 87 74 86 74 / 20 10 20 10  
JAX 91 71 88 72 / 20 10 20 10  
SGJ 89 72 86 73 / 10 0 10 10  
GNV 92 70 89 69 / 10 0 20 10  
OCF 93 69 90 70 / 10 0 20 10  
 

 
   
JAX WATCHES/WARNINGS/ADVISORIES
 
 
FL...COASTAL FLOOD ADVISORY UNTIL 8 PM EDT THIS EVENING FOR CLAY-  
COASTAL DUVAL-FLAGLER-INLAND DUVAL-PUTNAM-ST. JOHNS.  
 
GA...NONE.  
AM...NONE.  

 
 

 
 
HESS/CORDERO  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab FL Page
The Nexlab GA Page Main Text Page