196  
FXUS64 KHUN 241131  
AFDHUN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE HUNTSVILLE AL  
631 AM CDT FRI MAY 24 2019  
   
UPDATE
 
 
FOR 12Z TAFS.  
 

 
   
NEAR TERM
 
(TODAY)  
ISSUED AT 400 AM CDT FRI MAY 24 2019  
 
QUIET AND SEASONABLY WARM WX CONDITIONS PREVAIL ACROSS THE CNTRL TN  
VALLEY THIS EARLY FRI MORNING, AS A STRONG UPPER RIDGE AXIS REMAINS  
IN PLACE OVER THE SE GULF STATES. TEMP TRENDS ARE MAINLY IN THE UPPER  
60S/LOWER 70S, AND THESE VALUES COULD EASILY DROP ANOTHER COUPLE OF  
DEGREES BEFORE DAYBREAK. TEMPS SHOULD THEN QUICKLY REBOUND WITH THE  
ONSET OF DAYTIME HEATING, WITH AFTERNOON HIGHS AGAIN XPCTED TO CLIMB  
WELL INTO THE LOWER/PERHAPS MID 90S. THIS AGAIN WILL BE AROUND 10F  
ABOVE NORMAL (83F) FOR THIS TIME OF THE YR. RECORD MAX TEMP FOR THIS  
DAY IS 96F AND THIS IS VALID FOR BOTH HUNTSVILLE/MUSCLE SHOALS.  
 
THE OOZ NAM12 IS EVER SO SLIGHTLY TRYING TO WEAKEN THE UPPER RIDGE A  
BIT LATER TODAY, THEREBY ALLOWING MORE OF A SW FLOW REGIME TO DEVELOP  
OVER THE LOWER MS VALLEY INTO THE WRN HALF OF THE AREA. WITH PWATSS  
AROUND 1.25 INCHES AND SBCAPE VALUES CLIMBING INTO THE 1-2K J/KG,  
THIS MAY BE ENOUGH TO TRIGGER A FEW SHOWERS/TSTMS THIS AFTERNOON.  
HOWEVER, THE 00Z ECMWF/GFS DO NOT SHOW THE UPPER RIDGE WEAKENING AS  
MUCH AND LIKEWISE TREND A LITTLE MORE ON THE DRY SIDE, CONSISTENT  
WITH THE ONGOING FORECAST. WILL MAINTAIN A DRY FORECAST TODAY GIVEN  
THE BIASES IN THE BLENDED GUIDANCE TRENDING LOW, HOWEVER CANNOT  
TOTALLY RULE OUT A COUPLE OF SHOWERS/TSTMS LATER THIS AFTERNOON.  
   
SHORT TERM
 
(TONIGHT THROUGH SUNDAY)  
ISSUED AT 400 AM CDT FRI MAY 24 2019  
 
PERSISTENCE WILL BE THE KEY FACTOR FOR THE REMAINDER OF THE FORECAST,  
WITH UNSEASONABLY HOT/DRY WX CONDITIONS CONTINUING INTO THE MEMORIAL  
DAY WEEKEND. PRETTY MUCH ALL OF THE LATEST MODEL SUITES SHOW THE  
SUBTLE WEAKENING TREND IN THE UPPER RIDGE THIS WEEKEND, AS THE CENTER  
OF THE AXIS DRIFTS SLIGHTLY TO THE SOUTH. THIS WILL FAVOR A PATTERN  
WHERE UPPER WAVES TRAVERSE EWD ACROSS THE NRN FRINGE OF THE UPPER  
RIDGE AXIS, ALTHOUGH MOST/IF NOT ALL OF THIS ACTIVITY SHOULD REMAIN  
WELL NORTH OF THE CNTRL TN VALLEY. CANNOT AGAIN TOTALLY RULE OUT A  
COUPLE OF SHOWERS/TSTMS DEVELOPING OVER A SMALL PART OF THE AREA THIS  
WEEKEND, BUT THE BLENDED GUIDANCE/PROB REMAINS FAIRLY LOW FOR NOW.  
AFTERNOON HIGHS WILL CONTINUE TO TREND IN THE LOWER/MID 90S WHILE  
OVERNIGHT LOWS LOOK TO BE MAINLY IN THE MID/UPPER 60S.  
   
LONG TERM
 
(SUNDAY NIGHT THROUGH THURSDAY)  
ISSUED AT 400 AM CDT FRI MAY 24 2019  
 
OVER AND NEAR THE GREATER NORTH AMERICAN DOMAIN, A SEEMINGLY ENDLESS  
SETUP OF TROUGHING WEST AND RIDGING EAST CONTINUED. ON A LARGER  
SCALE, A BLOCKING PATTERN THAT HAD KEPT THIS CONFIGURATION IN PLACE  
WAS BEGINNING TO SHOW SIGNS OF WEAKENING BY EARLY NEXT WEEK.  
 
OUT WEST, AN UPPER LEVEL SYSTEM CURRENTLY OVER THE GULF OF ALASKA  
WILL MOVE SOUTHWARD ALONG THE WEST COAST, HELPING TO FORTIFY  
TROUGHING THAT HAS BEEN IN PLACE THERE. BY EARLY NEXT WEEK, THIS  
SYSTEM AT THIS TIME SHOULD BE ACROSS CALIFORNIA, THEN WILL EJECT TO  
THE ENE TOWARDS THE SOUTHERN GREAT LAKES BY THE LATTER HALF OF NEXT  
WEEK. CLOSER TO THIS REGION, THE UPPER RIDGE SITUATED OVER THE  
SOUTHEASTERN STATES AND NORTHEAST GULF OF MEXICO OVER THE PAST WEEK  
WILL ALSO GRADUALLY WEAKEN AND MOVE FURTHER SOUTH. SURFACE HIGH  
PRESSURE OFF OF THE SOUTHEAST COAST WILL REMAIN IN PLACE DURING THIS  
PERIOD, MAINTAINING A SOUTHERLY FLOW ACROSS THE TENNESSEE VALLEY.  
GIVEN THAT THE UPPER RIDGE WILL HAVE MAXIMUM HEIGHTS NEARING 593  
DECAMETERS AND VERY WARM TEMPERATURES ABOVE THE SURFACE (850MB  
20-23C), WILL TRANSLATE TO VERY WARM TO HOT FOR LATE MAY CONDITIONS  
TO GET THE "OFFICIAL" SUMMER SEASON STARTED.  
 
MEMORIAL DAY SHOULD FEATURE GENERALLY HOT CONDITIONS WITH HIGH  
TEMPERATURES IN THE MID 90S. A DEGREE OR TWO WARMER IS FORECAST ON  
TUESDAY. HOWEVER DESPITE A SOUTHERLY FLOW BRINGING MOISTURE FROM THE  
GULF, DEWPOINT VALUES DURING THIS TIME SHOULD REMAIN IN THE LOW 60S,  
WHICH WILL RESULT IN THE HEAT INDEX VALUES CLOSER TO THE DRYBULB  
TEMPERATURES. DEWPOINTS RISING INTO THE MID 60S WILL CAUSE THE HEAT  
INDICES TO RISE A COUPLE OF DEGREES; HOWEVER THEY SHOULD REMAIN BELOW  
100 DEGREES INTO THE MIDDLE OF NEXT WEEK. OUR HEAT ADVISORY CRITERIA  
HAS HEAT INDICES OF 105 OR GREATER, AND/OR AIR TEMPS 103 OR HIGHER.  
OVERALL TEMPERATURES BEGIN COOLING SOMEWHAT FOR THE MIDWEEK AND  
BEYOND, WITH HIGHS BY NEXT THURSDAY "ONLY" OF AROUND 90.  
 
THE UPPER LOW EXITING THE WEST COAST WILL BRING A COLD FRONT BOUNDARY  
TOWARDS THE REGION DURING THE THU/FRI PERIOD NEXT WEEK. THE APPROACH  
OF THIS FRONT AND MORE INSTABILITY WILL RESULT IN MORE CLOUDS, AND  
FINALLY BRING CHANCES OF NEEDED RAINFALL WED NIGHT AND ON THU.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)  
ISSUED AT 631 AM CDT FRI MAY 24 2019  
 
WITH A STRONG AREA OF HIGH PRESSURE IN PLACE ACROSS THE ERN GULF  
STATES, VFR CONDS ARE XPCTED THRU THE PERIOD. SCT MID/HIGH CLOUDS MAY  
BEGIN TO SPREAD INTO THE AREA FROM THE SW LATE THIS MORNING BEFORE  
DIMINISHING THIS EVENING. AN ISO SHRA/TSRA CANNOT BE RULED OUT ACROSS  
NW AL THIS AFTERNOON AS WELL, BUT THE PROB IS VERY LOW FOR NOW.  
 

 
   
HUN WATCHES/WARNINGS/ADVISORIES
 
 
AL...NONE.  
TN...NONE.  

 
 

 
 
NEAR TERM...09  
SHORT TERM...09  
LONG TERM...RSB  
AVIATION...09  
 
FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE  
AT WEATHER.GOV/HUNTSVILLE.  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab AL Page
The Nexlab TN Page Main Text Page