761  
FXUS64 KHUN 240317  
AFDHUN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE HUNTSVILLE AL  
917 PM CST THU NOV 23 2017  
   
NEAR TERM
 
(REST OF TONIGHT)  
ISSUED AT 915 PM CST THU NOV 23 2017  
 
A SURFACE RIDGE AXIS IS MOVING SLOWLY SOUTHWARD ACROSS THE AREA THIS  
EVENING. ATTENDANT BROAD SCALE SUBSIDENCE IS LEADING TO A CLEAR SKY  
ACROSS THE REGION AND LIGHT SFC WINDS...ESSENTIALLY GOOD RADIATIONAL  
COOLING CONDITIONS. TEMPERATURES HAVE FALLEN INITIALLY A LITTLE  
FASTER THAN FORECAST AND GENERALLY SMALL ADJUSTMENTS WERE MADE,  
MAINLY TO LOWER TEMPS IN SOME LOCATIONS BASED ON THE LATEST  
TRENDS/VALUES AN IN ACCORDANCE WITH TERRAIN/MICROCLIMATE  
CONSIDERATIONS. OTHERWISE, NO SIGNIFICANT CHANGES WERE MADE. OVERALL,  
LOW TEMPERATURES TONIGHT EXPECTED TO BE IN THE UPPER 20S TO LOWER  
30S (ALTHOUGH A LITTLE WARMER NEAR THE LARGER TN RIVER LAKES).  
   
SHORT TERM
 
(FRIDAY THROUGH SATURDAY)  
ISSUED AT 113 PM CST THU NOV 23 2017  
 
FRIDAY SHOULD BE ANOTHER PLEASANT DAY, ALBEIT WARMER, AS WEAK  
SOUTHERLY FLOW AHEAD OF AN APPROACHING COLD FRONT BOOSTS TEMPERATURES  
BY ANOTHER 5 DEGREES OR SO. WITH STILL FAIRLY MINIMAL MOISTURE RETURN  
TO SPEAK OF (DESPITE THE SOUTHERLY FLOW), THERE SHOULD NOT BE MUCH  
CLOUD COVER DURING THE DAY. HIGHS SHOULD REACH WELL INTO THE LOWER  
60S, AND BASED ON GUIDANCE BIASES, THE FORECAST WILL HAVE A FEW SPOTS  
REACHING THE MID 60S. FRIDAY NIGHT WILL BE MILD, BUT CLOUD COVER WILL  
INCREASE MARKEDLY AFTER MIDNIGHT.  
 
A WEAK FRONT WILL MOVE ACROSS THE REGION SATURDAY AFTERNOON. MOISTURE  
REMAINS LIMITED TO AREAS ABOVE ~700MB SO THE FRONT SHOULD PRODUCE ONLY  
AN INCREASE IN CLOUDS. THE 12Z GFS GENERATED A LITTLE QPF (JUST  
0.01-0.02 INCHES) BUT THERE IS LITTLE SUPPORT FOR THIS FROM THE SREF  
OR NAEFS PROBABILITIES. STILL, A SPRINKLE OR TWO CANNOT BE ENTIRELY  
RULED OUT, MAINLY NORTH OF THE TENNESSEE RIVER.  
   
LONG TERM
 
(SATURDAY NIGHT THROUGH WEDNESDAY)  
ISSUED AT 113 PM CST THU NOV 23 2017  
 
ANOTHER DRY AND SEASONABLE PERIOD WILL FOLLOW BEHIND THE SATURDAY  
FRONT. TEMPERATURES SUNDAY AND MONDAY WILL HOVER RIGHT AROUND NORMAL  
FOR LATE NOVEMBER.  
 
THE PATTERN BECOMES A LITTLE MORE INTERESTING TUESDAY INTO WEDNESDAY  
AS A DEEP PACIFIC-ORIGINATING TROUGH DIGS INTO THE SOUTHERN PLAINS,  
SETTING UP ROBUST SOUTHERLY FLOW AHEAD OF THE TROUGH. DETERMINISTIC  
MODELS (GFS/ECMWF) HAVE CONSISTENTLY BEEN FAR APART IN TERMS OF  
TIMING, AS ONE MIGHT EXPECT WITH A FEATURE OF THIS AMPLITUDE.  
WHILE MOST OF THE ENSEMBLES (GEFS/NAEFS AND EVEN ECMWF) ARE FASTER  
WITH THIS FEATURE, THE ALREADY-AMPLIFIED PATTERN FAVORS A SLOWER  
PROGRESSION. SO THE FORECAST WILL CONTINUE TO SPREAD LOW-MODERATE  
POPS OVER THE BROADER TIME PERIOD, WEDNESDAY THROUGH THURSDAY. EVEN  
THEN, THERE IS NOT MUCH CONFIDENCE IN RECEIVING A LOT OF RAIN, SINCE  
FEW EXTENDED-RANGE MODELS CREATE MUCH MOISTURE RETURN DESPITE THE  
SOUTHERLY FLOW. THE FORECAST WILL TREND WARMER THAN BLENDS/MOS  
TUESDAY AMIDST PREFRONTAL WARM ADVECTION, BUT MORE TOWARDS THE MEAN  
WED-THU GIVEN THE UNCERTAINTY ABOUT THE TIMING OF THE TROUGH.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)  
ISSUED AT 630 PM CST THU NOV 23 2017  
 
VFR CONDITIONS ARE EXPECTED AT KHSV/KMSL TAF SITES OVER THE NEXT 24  
HOURS. DESPITE CLEAR SKY/LGT WIND CONDITIONS, FOG DEVELOPMENT IS NOT  
ANTICIPATED AT TAF SITES TONIGHT. A RIDGE AXIS WILL MOVE SEWRD  
ACROSS THE AREA TONIGHT AND EARLY FRIDAY RESULTING IN LGT/VRB SFC  
WINDS. HOWEVER, WINDS WILL RETURN FROM THE SSW BY ABOUT 16Z AS THE  
RIDGE AXIS SHIFTS TO OUR SE TOMORROW.  
 

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

 
 

 
 
NEAR TERM...KDW  
SHORT TERM...BCC  
LONG TERM...BCC  
AVIATION...KDW  
 
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