604  
FXUS64 KMEG 182331  
AFDMEG  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MEMPHIS TN  
631 PM CDT WED JUL 18 2018  
   
DISCUSSION
 
 
UPDATED FOR 00Z AVIATION DISCUSSION.  
 

 
   
PREV DISCUSSION
 
/ISSUED 312 PM CDT WED JUL 18 2018/  
 
DISCUSSION...  
 
A WET AFTERNOON IS UNDERWAY FOR SOUTHWESTERN PORTIONS OF THE  
MIDSOUTH, INCLUDING MUCH OF THE MEMPHIS METRO. A DECAYING MCS THAT  
MOVED INTO THE REGION EARLY THIS MORNING HELPED SPARK A LINE OF  
CONVECTION AROUND MIDDAY FROM NEAR WALNUT RIDGE AND JONESBORO,  
SOUTHEAST THROUGH THE SOUTHERN MEMPHIS METRO. THE STORM PREDICTION  
CENTER (SPC) HAS INCREASED THE RISK OF SEVERE WEATHER TO MARGINAL  
WHERE STORMS HAVE SET-UP, WITH DAMAGING WINDS FROM DOWNBURSTS  
BEING THE PRIMARY THREAT. DRIER, MORE STABLE AIR WILL KEEP MUCH OF  
THE REST OF WEST TENNESSEE DRY WHILE THE REMAINDER OF THE  
MIDSOUTH CAN EXPECT A LEAST A CHANCE OF PRECIPITATION AS THESE  
STORMS PROPAGATE TOWARDS THE SOUTHEAST THIS EVENING. RAIN AND  
CLOUD COVER WILL KEEP HEAT INDICES UNDER CONTROL THIS AFTERNOON,  
PREVENTING THE NEED FOR A HEAT ADVISORY. NEVERTHELESS, LOCATIONS  
THAT HAVEN'T RECEIVED RAINFALL ARE SEEING TEMPERATURES PEAK NEAR  
90 DEGREES WITH HEAT INDICES NEAR 100 DEGREES.  
 
MOST CONVECTIVE ALLOWING MODELS (CAMS) INDICATE THAT STORMS WILL  
WANE SIGNIFICANTLY THIS EVENING AS DAYTIME HEATING DIMINISHES...  
BUT RIPPLES EMBEDDED IN NORTHWEST FLOW ALOFT COULD SUPPORT LESSER  
ACTIVITY OF SHOWERS AND STORMS OVERNIGHT, AS INDICATED BY SOME CAM  
SOLUTIONS. CONVECTION SHOULD NOT BE AS ORGANIZED TOMORROW, BUT  
DAYTIME HEATING WITH CONTINUING NORTHWEST FLOW WILL SUPPORT A  
CHANCE OF AFTERNOON STORMS. DEEP LAYER SHEAR WILL BE HIGHER  
TOMORROW, RESULTING IN A MARGINAL RISK FOR SEVERE WEATHER...  
CONDITIONAL UPON STORM DEVELOPMENT. INCREASED SOUTHERLY FLOW WILL  
LEAD TO SLIGHTLY HIGHER TEMPERATURES TOMORROW, BUT NOT CONFIDENT  
ENOUGH THAT WE WILL REACH HEAT ADVISORY CRITERIA AT THIS TIME DUE  
TO EXPECTED CLOUD COVER. MS/AR DELTA COUNTIES WILL HAVE THE BEST  
CHANCE OF REACHING THE THRESHOLD.  
 
BY FRIDAY NORTHWEST FLOW ALOFT TIGHTENS SIGNIFICANTLY AS A  
SUBSTANTIAL TROUGH TO OUR NORTH DEEPENS AND DIVES SOUTHEASTWARD.  
MOST OF THE LIFT ASSOCIATED WITH THIS TROUGH WILL REMAIN TO OUR  
NORTH AND EAST. PORTIONS OF NORTHWEST TENNESSEE WILL HAVE THE  
BEST CHANCE FOR SEVERE WEATHER, AS INDICATED BY ANOTHER MARGINAL  
RISK BY SPC. THE BIGGER IMPACT FRIDAY WILL BE HEAT, AS THIS LOOKS  
TO BE THE WARMEST DAY IN THE FORECAST PACKAGE. ANTICIPATING A HEAT  
ADVISORY FOR THE BULK OF THE AREA AT THIS TIME, AS HEAT INDICES  
SHOULD EASILY PEAK BETWEEN 105 TO 110 DEGREES.  
 
DRIER AND SLIGHTLY LESS MISERABLE CONDITIONS WILL ARRIVE IN THE  
MIDSOUTH ON SATURDAY AS SURFACE WINDS BECOME NORTHWESTERLY AND  
SLIGHTLY DRIER AIR TRICKLES INTO THE MIDSOUTH OVER THE WEEKEND.  
HEAT INDICES WILL STILL PEAK NEAR 100 DEGREES, WITH SUNDAY  
LOOKING LIKE THE LEAST OPPRESSIVE DAY FOR HEAT.  
 
HEADING INTO NEXT WEEK THE TROUGH THAT DIPPED INTO THE EASTERN US  
LOOKS TO GET BLOCKED IN BY LARGE SCALE RIDGES TO OUR EAST AND  
WEST. THIS WILL RESULT IN A LOW CONFIDENCE PRECIPITATION FORECAST,  
AS SMALL CHANGES IN THE TRACK OF THE TROUGH AND EVENTUAL CUT-OFF  
LOW WILL HAVE LARGE IMPACTS ON STORM COVERAGE. FOR NOW KEEPING A  
SLIGHT CHANCE OF POPS IN THAT RANGE. THIS PATTERN SHOULD HELP TO  
KEEP OPPRESSIVE HEAT AWAY FROM THE MIDSOUTH IN THE EXTENDED  
PERIOD... BUT BEING LATE JULY STRONG SOLAR INSOLATION WILL STILL  
RESULT IN HIGH TEMPERATURES IN THE LOW 90S AND LOW TEMPS IN THE 70S.  
 
WLC  
   
AVIATION
 
 
00Z TAF CYCLE  
 
VFR THROUGH THE PERIOD...WITH THE EXCEPTION OF SHOWERS AND LIGHT  
FOG FORMING AT MKL. HAVE BEEN MORE OPTIMISTIC WITH OVERNIGHT  
CONVECTION. THUNDERSTORMS WILL BE AROUND BUT BELIEVE MORE  
ISOLATED IN COVERAGE...SO HAVE PLACED VCSH AND TEMPO PERIODS OF  
PASSING SHOWERS. CONFIDENCE IS NOT HIGH HOWEVER AND MAY CHANGE IF  
RADAR BEGINS LIGHTING UP AGAIN. ALSO PLACED A SCATTERED MVFR  
STRATUS DECK IN NEAR SUNRISE. LATER IN THE PERIOD THUNDERSTORMS  
HOLDING OFF UNTIL NEAR SUNSET AND POINTS THEREAFTER AS NEXT SYSTEM  
DROPS SOUTHEAST FROM MISSOURI...HENCE THE VCTS AT MEM. LIGHT  
WINDS BECOMING SOUTH AT 6-9KTS. SOME GUSTS WITH PASSING SHOWERS.  
 
JAB  
 

 
   
MEG WATCHES/WARNINGS/ADVISORIES
 
 
AR...NONE.  
MO...NONE.  
MS...NONE.  
TN...NONE.  

 
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab TN Page
The Nexlab MS Page
The Nexlab AR Page Main Text Page