661  
FXUS64 KHUN 191722  
AFDHUN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE HUNTSVILLE AL  
1122 AM CST TUE JAN 19 2021  
   
UPDATE
 
 
FOR 18Z TAFS.  
 

 
   
NEAR TERM
 
(REST OF TODAY)  
ISSUED AT 802 AM CST TUE JAN 19 2021  
 
SCATTERED LIGHT RAIN SHOWERS WILL GRADUALLY MOVE INTO THE TENNESSEE  
VALLEY THROUGHOUT THE DAY AS A WEAK SHORTWAVE PUSHES ACROSS THE AREA.  
THE BEST COVERAGE OF SHOWERS WILL BE IN AREAS ALONG AND SOUTH OF THE  
TENNESSEE RIVER WHICH WILL BE CLOSER TO A STALLED, DIFFUSE SURFACE  
BOUNDARY IN CENTRAL ALABAMA. MOISTURE IS FAIRLY LIMITED AND CONFINED  
TO THE LOW-LEVELS AND AS A RESULT, THINK TOTAL QPF OF 0.1 TO 0.2" OR  
LESS WILL BE COMMON. MAIN CHANGE TO THE FORECAST THIS MORNING WAS TO  
SPEED UP THE TIMING OF MENTIONABLE POPS AS WE'RE STARTING TO SEE  
SOME VERY LIGHT ACCUMULATIONS IN NW ALABAMA AS OF 14Z. ALSO,  
INCREASED POPS TO "LIKELY" IN OUR FAR SOUTHERN ZONES THIS AFTERNOON  
DUE TO BETTER CONFIDENCE OF COVERAGE THERE. OTHERWISE, EVERYTHING  
REMAINS ON TRACK. EXPECT AN OVERCAST SKY, WITH TEMPERATURES PEAKING  
IN THE LOW TO MID 50S BY THIS AFTERNOON AS WARM, MOIST AIR CONTINUES  
TO ADVECT IN FROM THE SOUTH.  
   
SHORT TERM
 
(TONIGHT THROUGH THURSDAY NIGHT)  
ISSUED AT 232 AM CST TUE JAN 19 2021  
 
NORTHWEST FLOW WILL TAKE OVER BY WEDNESDAY, AND SFC HIGH PRESSURE  
WILL SHIFT EAST INTO THE LOWER MS VALLEY REGION. A SLIGHTLY COOLER  
AIRMASS WILL BE USHERED IN THROUGH THE MORNING HOURS, LIMITING HIGH  
TEMPERATURES TO NEAR 50 DEGREES FOR THE DAY. EXPECT DRY CONDITIONS  
THROUGH THE EVENING HOURS, BUT WILL SEE A GRADUAL INCREASE IN CLOUDS  
AS ONCE AGAIN WE SEE MOISTURE ADVECTION FROM THE WESTERN GULF. A WARM  
FRONT WILL SURGE NORTH THURSDAY MORNING, AND WILL ONCE AGAIN SEE  
RAIN CHANCES INCREASE FROM WEST TO EAST THROUGH THE AFTERNOON. EXPECT  
THE HEAVIEST RAIN TO FALL THURSDAY MORNING, BEFORE HIGH PRESSURE  
SLOWLY PUSHES THIS BOUNDARY SOUTH THROUGH THE CWA. EXPECT TO SEE A  
BIT MORE RAIN FROM THIS SYSTEM, BUT STILL GENERALLY LESS THAN 0.5"  
THROUGH THE REMAINDER OF THE SHORT TERM PERIOD. AFTERNOON TEMPS WILL  
TOP OUT IN THE MID 50S ON THURSDAY, AND AT LEAST SLIGHT CHANCES FOR  
RAIN WILL LINGER THROUGH THURSDAY NIGHT, MAINLY SOUTH OF THE TN RIVER  
ONCE AGAIN.  
   
LONG TERM
 
(FRIDAY THROUGH MONDAY)  
ISSUED AT 232 AM CST TUE JAN 19 2021  
 
LIGHT RAIN WILL BE ONGOING FRIDAY AS A SHORTWAVE QUICKLY SPEEDS EAST  
WITHIN THE QUASI-ZONAL FLOW AT 5H. HOWEVER, THE COLD FRONT WILL  
REMAIN WELL TO OUR SOUTH, WITH RISING PRESSURES OVER THE TN VALLEY AS  
HIGH PRESSURE BUILDS SOUTHEAST FROM THE UPPER MS VALLEY AND NORTHERN  
PLAINS. AFTER RAIN ENDS SOMETIME BY FRIDAY AFTERNOON, DRY WEATHER IS  
FORESEEN THROUGH AT LEAST SATURDAY NIGHT AS THE HIGH BUILDS FURTHER  
ACROSS THE OH VALLEY AND FURTHER THROUGH THE SOUTHEAST U.S. MID TO  
UPPER LEVEL RIDGING WILL SHIFT EAST ON SUNDAY, BUT THE GFS AND ECMWF  
DIFFER ON HOW QUICKLY RAIN CHANCES MAY BEGIN AS SOUTHERLY FLOW  
DEVELOPS. THESE DIFFERENCES CONTINUE THROUGH EARLY NEXT WEEK AS WELL  
WITH TIMING AND EVOLUTION ISSUES OF YET ANOTHER UPPER LOW DIGGING  
INTO THE DESERT SW. CONFIDENCE IS GREAT ENOUGH TO KEEP POPS IN THE  
LIKELY RANGE FOR MONDAY USING SUGGESTED BLENDED GUIDANCE WITH A  
FRONTAL BOUNDARY SETTLING EITHER JUST TO OUR NORTH (ECMWF) OR INTO  
NORTH AL (GFS). THE MODELS (ESPECIALLY THE GFS) DEPICTS THE  
POTENTIAL FOR HEAVY RAIN ALONG THIS BOUNDARY, WHICH SYNOPTICALLY  
WOULD MAKE SENSE GIVEN FEED OF HIGH PW AIR INTO THE BOUNDARY WITHIN A  
5H RIDGE AXIS AHEAD OF THE ADVANCING SHORTWAVE.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)  
ISSUED AT 1122 AM CST TUE JAN 19 2021  
 
MVFR CONDITIONS WILL PREVAIL AT EACH TERMINAL DUE TO 2.5 KFT CEILINGS  
THIS AFTERNOON AS -SHRA MOVES INTO THE REGION WITH A PASSING FRONT.  
CONFIDENCE TOO LOW TO MENTION AT EITHER TERMINAL, BUT HAVE INCLUDED  
VCSH BETWEEN 18-00Z. BREEZY SOUTHERLY WINDS WILL VEER TO THE NW IN  
WAKE OF THE FRONTAL PASSAGE THIS EVENING. DRY AIR WILL HELP TO SCOUR  
OUT THE LOWER CLOUDS LATE TONIGHT INTO EARLY WEDNESDAY MORNING AND  
EXPECT A RETURN TO VFR CONDITIONS LATE IN THE PERIOD.  
 

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

 
 

 
 
NEAR TERM...AMP.24  
SHORT TERM...25  
LONG TERM...17  
AVIATION...AMP.24  
 
FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE  
AT WEATHER.GOV/HUNTSVILLE.  
 
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