268  
FXUS63 KLMK 142348  
AFDLMK  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LOUISVILLE KY  
648 PM EST THU DEC 14 2017  
   
..UPDATED AVIATION DISCUSSION
 
 
   
SHORT TERM
 
(THIS EVENING THROUGH FRIDAY NIGHT)  
ISSUED AT 300 PM EST THU DEC 14 2017  
 
THE SHORT TERM PERIOD WILL FEATURE MAINLY QUIET CONDITIONS AS HIGH  
PRESSURE BUILDS IN FROM THE WEST. TEMPERATURES THIS AFTERNOON WILL  
REMAIN IN THE 30S WITH PARTLY TO MOSTLY CLOUDY SKIES. WE SHOULD SEE  
THE CLOUDS BREAK UP LATER TONIGHT WITH TEMPERATURES FALLING INTO THE  
LOWER-MID 20S.  
 
A SHORT WAVE TROUGH AXIS WILL SWING THROUGH THE REGION. MOISTURE  
LOOKS TO REMAIN FAIRLY LIMITED. WE'LL PROBABLY SEE AN INCREASE IN  
CLOUDINESS ACROSS SOUTHERN IN AND NORTHERN KY. HIGHS LOOK TO WARM  
INTO THE UPPER 30S WITH A FEW LOWER 40S DOWN ACROSS SOUTHERN KY.  
LOWS FRIDAY NIGHT LOOK SEASONALLY COLD WITH LOWS IN THE MID-UPPER  
20S.  
   
LONG TERM
 
(SATURDAY THROUGH THURSDAY)  
ISSUED AT 300 PM EST THU DEC 14 2017  
 
SATURDAY THROUGH THURSDAY...  
 
SURFACE HIGH PRESSURE IS FORECAST TO MOVE THROUGH THE SOUTHEASTERN  
US ON SATURDAY WHICH SHOULD KEEP OUR REGION FAIRLY DRY WITH SLIGHTLY  
MILDER TEMPERATURES. CURRENT DATA SUGGESTS HIGHS IN THE UPPER 40S  
TO THE LOWER 50S. CLOUDS WILL INCREASE SATURDAY NIGHT AS A  
SOUTHERN STREAM SYSTEM APPROACHES FROM THE SOUTHWEST. CURRENT  
THINKING IS THAT PRECIPITATION WILL LIKELY HOLD OFF UNTIL AFTER  
SUNRISE ON SUNDAY. LOWS OF 30-35 LOOK DECENT FOR SATURDAY NIGHT.  
 
PRECIPITATION WILL RAPIDLY EXPAND IN COVERAGE ON SUNDAY. IT APPEARS  
THAT WE SHOULD SEE PRECIPITATION BREAK OUT BY MID-MORNING. THERMAL  
PROFILES ARE A LITTLE COLDER HERE, SO A WINTRY MIX COULD BE SEEN AT  
ONSET, IF PROFILES REMAIN COLD ENOUGH. THAT WOULD NOT LAST ALL THAT  
LONG AS STRONG WARM AIR ADVECTION ALLOWS THE COLUMN TO WARM FAIRLY  
QUICKLY. PLENTY OF CLOUDS AND PRECIPITATION SHOULD KEEP TEMPERATURES  
DOWN A BIT. WE PLAN ON GOING A LITTLE COOLER THAN THE GUIDANCE WITH  
HIGHS IN THE UPPER 30S TO THE LOWER 40S NORTH OF THE WK/BG PARKWAYS,  
AND MID-UPPER 40S ACROSS THE SOUTHERN 2/3RDS OF KY. SCATTERED  
SHOWERS LOOK TO CONTINUE INTO SUNDAY NIGHT WITH LOWS IN THE UPPER  
30S TO THE LOWER 40S.  
 
IT STILL APPEARS THAT WE'LL SEE A LITTLE BIT OF LULL IN THE WEATHER  
FOR MONDAY. HOWEVER, THAT LULL WON'T LAST LONG AS A SECONDARY WAVE  
SHOULD PASS INTO THE REGION LATE MONDAY INTO TUESDAY BRINGING  
ANOTHER ROUND OF RAIN SHOWERS. HIGHS ON MONDAY LOOK TO WARM INTO  
THE LOWER 50S WITH OVERNIGHT LOWS IN THE 40S. SOME SHOWERS MAY  
LINGER INTO TUESDAY MORNING WITH A DRYING TREND EXPECTED INTO THE  
AFTERNOON. HIGHS ON TUESDAY LOOK TO WARM INTO THE LOWER 50S WITH  
LOWS TUESDAY NIGHT FALLING INTO THE LOWER 30S. AN AREA OF HIGH  
PRESSURE LOOKS TO THEN MOVE INTO THE REGION ON WEDNESDAY WITH HIGHS  
GENERALLY INTO THE UPPER 40S TO THE LOWER 50S. LOWS WEDNESDAY NIGHT  
LOOK TO COOL BACK INTO THE 30S. A RETURN TO A SOUTHWEST FLOW LOOKS  
TO BEGIN IN EARNEST ON THURSDAY WITH HIGHS WARMING INTO THE LOWER-  
MIDDLE 50S.  
 
FRIDAY INTO THE WEEK OF CHRISTMAS...  
 
THE LATEST DATA STILL SUGGESTS A HIGHLY ACTIVE PERIOD OF WEATHER  
COMING FOR THE HOLIDAY WEEKEND AND INTO THE WEEK OF CHRISTMAS. THE  
LATEST DATA SUGGESTS THAT A STORM SYSTEM WILL AFFECT THE REGION LATE  
THURSDAY AND INTO FRIDAY IN THE FORM OF A COLD FRONT. WE'LL BE ON  
THE WARM SIDE OF THIS SYSTEM WITH A PERIOD OF SHOWERS (POSSIBLY A  
FEW STORMS) PUSHING THROUGH THE REGION. THAT FRONT LOOKS TO PUSH  
OFF TO THE EAST WITH COLDER CONDITIONS PUSHING INTO THE REGION BY  
SATURDAY. HIGHS MAY PUSH INTO THE UPPER 50S TO AROUND 60 VERY EARLY  
FRIDAY BEFORE FALLING IN THE WAKE OF THE COLD FRONT. HIGHS BY  
SATURDAY LOOK TO COOL BACK INTO THE 30S.  
 
AS WE'VE BEEN HIGHLIGHTING FOR THE LAST FEW DAYS, LONG RANGE SIGNAL  
ANALYSIS HAS BEEN STRONGLY ADVERTISING A SIGNAL PASSAGE IN THE DEC  
23-24TH TIME FRAME. THIS IS IN THE RANGE OF THE LONG RANGE  
DYNAMICAL MODELS AND BOTH THE GFS AND EURO BOTH SHOW THIS SYSTEM  
POSSIBLY IMPACTING THE REGION IN THE ABOVE TIME FRAME. HOWEVER, THE  
DETAILS AS TO THE SENSIBLE WEATHER WITH THIS SYSTEM HAVE YET TO BE  
WORKED OUT.  
 
THE UPPER LEVEL PATTERN IS FORECAST TO BE VERY AMPLIFIED ACROSS NOAM  
DURING THIS PERIOD. THE PATTERN IS FORECAST TO HAVE A STRONG  
EASTERN PACIFIC RIDGE JUST OFF THE US COAST EXTENDING INTO ALASKA  
WITH A CORRESPONDING DOWNSTREAM TROUGH AXIS ACROSS THE PLAINS AND  
ANOTHER RIDGE IN THE WESTERN ATLANTIC. THE CRUX OF THE FORECAST  
LOOKS TO DEPEND ON HOW STRONG THE RIDGE OVER THE PACIFIC AND OFF THE  
EAST COAST OF THE US WILL BE.  
 
IN GENERAL TERMS, IF THE PACIFIC/AK RIDGE IS STRONG, THE  
CORRESPONDING SEUS/SW ATLANTIC RIDGE WILL LIKELY BE STRONG,  
RESULTING IN A WARMER PATTERN OVER THE EASTERN US WITH THE BULK OF  
THE COLD IN THE WESTERN US AND IN THE PLAINS. ON THE OTHER HAND, IF  
THE EAST PACIFIC/AK RIDGE IS NOT AS STRONG, THE CORRESPONDING  
SEUS/ATLANTIC RIDGE WILL PROBABLY NOT BE AS STRONG AND THE COLD AIR  
OVER THE PLAINS AND WEST MAY BE DISPLACED FURTHER EAST.  
 
DEPENDING ON THE UPPER LEVEL CONFIGURATION, THERE IS A VERY GOOD  
POSSIBILITY THAT AN ACTIVE STORM TRACK WILL BE SEEN ON THE WESTERN  
EDGE OF THE SE RIDGE. GOOD MOISTURE TRANSPORT AND LOW-LEVEL COLD  
AIR INSTRUCTION WOULD LIKELY SET THE STAGE FOR A MAJOR WINTRY EVENT  
MAINLY ON THE POLEWARD SIDE OF THE STORM TRACK. AT THIS TIME, THE  
OHIO VALLEY LOOKS TO BE WITHIN THE PATH OF THE STORM TRACK, BUT THE  
THERMAL PROFILE FORECAST IS FAR, FAR FROM CERTAIN. THE DYNAMICAL  
MODELS WILL CONTINUE OSCILLATE OVER THE COMING DAYS PRODUCING  
VARIOUS, IF NOT WILD SOLUTIONS. IT IS IMPORTANT NOT TO LOCK INTO  
ANY ONE SOLUTION. OUR ADVICE IS THAT IF YOU HAVE TRAVEL PLANS FOR  
LATE NEXT WEEK AND INTO CHRISTMAS, THAT YOU KEEP ABREAST OF THE  
LATEST FORECASTS OVER THE NEXT WEEK.  
 

 
   
AVIATION
 
(00Z TAF ISSUANCE)  
ISSUED AT 649 PM EST THU DEC 14 2017  
 
MAIN CONCERN FOR THE OVERNIGHT IS THE CURRENT VFR STRATO-CU DECK.  
MODELS CONTINUE TO SUGGEST THAT THE DECK WILL HANG AROUND HNB/BWG  
FOR MOST OF THE OVERNIGHT. COULD SEE SOME BUILD DOWN, BUT FOR NOW  
LIKE THE IDEA OF KEEPING IT JUST ABOVE THE MVFR/VFR THRESHOLD. AT  
SDF/LEX, MAINLY THINK THE DECK WILL STAY TO THE SOUTH AND WEST OF  
THESE SITES. NEVERTHELESS, LIKE THE IDEA OF HINTING AT A FEW-SCT  
LAYER AROUND 4 K FEET IN CASE.  
 
OTHERWISE, THE LIGHT WINDS OVERNIGHT WILL FIND THEIR WAY TO A STEADY  
WESTERLY COMPONENT ON FRIDAY MORNING. THEN, EXPECT A FEW GUSTS  
AROUND 20 MPH BY FRIDAY AFTERNOON WITH CONTINUED VFR CONDITIONS.  
 

 
   
LMK WATCHES/WARNINGS/ADVISORIES
 
 
IN...NONE.  
KY...NONE.  

 
 

 
 
SHORT TERM...MJ  
LONG TERM....MJ  
AVIATION...BJS  
 
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