533  
FXUS64 KTSA 211146  
AFDTSA  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TULSA OK  
646 AM CDT SAT OCT 21 2017  
   
AVIATION
 
 
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.  
MVFR CEILINGS AND BREEZY SOUTHERLY WINDS ACROSS MUCH OF THE CWA DURING  
THE MORNING HOURS ARE EXPECTED TO LIFT BACK TO JUST WITHIN THE  
VFR CATEGORY THIS AFTERNOON AHEAD OF A COLD FRONT APPROACHING THE  
CWA. THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG THE FRONT LATE  
THIS AFTERNOON AND SPREAD ACROSS THE CWA THIS EVENING AND TONIGHT.  
PERIODS OF IFR/MVFR CONDITIONS AND STRONG VARIABLE WINDS WILL BE  
POSSIBLE WITHIN THE STRONGER STORMS ALONG/NEAR THE LEADING LINE  
WITH MVFR CONDITIONS...NORTHWESTERLY WINDS AND DECREASING  
THUNDER/RAIN CHANCES BEHIND THE FRONT. WILL CARRY TEMPO GROUPS FOR  
TIMING OF THE STRONGER STORMS. CONDITIONS LOOK TO BEGIN LIFTING  
BACK TO VFR/CLEARING OUT ACROSS NORTHEAST OKLAHOMA LATE IN THE TAF  
PERIOD.  
 

 
   
PREV DISCUSSION
 
/ISSUED 320 AM CDT SAT OCT 21 2017/  
 
DISCUSSION...  
 
THE MAIN ITEMS OF INTEREST FOR THIS MORNING'S FORECAST WILL BE  
SEVERE STORM AND HEAVY RAIN POTENTIAL LATE TODAY AND TONIGHT WITH  
A COLD FRONT, AND RAIN CHANCES/TEMPS WITH A STRONG FRONT LATE NEXT  
WEEK.  
 
BROAD WESTERN CONUS TROUGH IS MARCHING TOWARD THE PLAINS THIS  
MORNING. A POCKET OF HIGHER PV WAS LOCATED NEAR THE FOUR CORNERS  
NEAR THE BASAL PORTION OF THE PARENT TROUGH. THIS ENERGY WILL MOVE  
OUT INTO THE CENTRAL/SOUTHERN PLAINS LATER TODAY AND WILL HELP  
PROVIDE LIFT ALONG WITH THE ASSOCIATED PACIFIC FRONT TO PRODUCE  
WIDESPREAD STORMS ACROSS THE REGION THRU TONIGHT.  
 
THE LATEST SHORT TERM HI-RES GUIDANCE INDICATES SOME SEMI-DISCRETE  
CELL DEVELOPMENT BETWEEN 21Z AND 00Z TO THE WEST/NORTHWEST OF  
TULSA, WHERE THE GREATEST THREAT FOR HAIL WILL BE WITH THIS EVENT.  
AN ISOLATED TORNADO IS POSSIBLE AS WELL. STORMS SHOULD QUICKLY  
GROW UPSCALE INTO A SQUALL LINE BY THE TIME THEY REACH TULSA AND  
WILL CONTINUE TO MARCH SOUTH AND EAST FROM THERE THRU THE NIGHT.  
SOME HI-RES GUIDANCE INDICATES THERE WILL BE POTENTIAL FOR SOME  
QLCS TORNADOES WHERE SEGMENTS OF THE LINE CAN BOW OUT TO THE EAST  
AND NORTHEAST. THIS THREAT WILL BE GREATEST TO THE WEST OF HIGHWAY  
69 IN NORTHEAST OKLAHOMA. IT WILL BE INTERESTING TO SEE HOW THE  
SUPERCELLS THAT ARE EXPECTED TO DEVELOP ACROSS CENTRAL OK EVOLVE,  
BECAUSE AS THEY BECOME A PORTION OF THE EVENTUAL SQUALL LINE,  
THEY COULD BRING THE BEST THREAT FOR QLCS TORNADOES AS THE SYSTEM  
MOVES INTO NORTHEAST OK. THE LINE SHOULD GENERALLY DECREASE IN  
INTENSITY AS IT MOVES INTO ARKANSAS AND SOUTHEAST OKLAHOMA OWING  
TO DECREASING INSTABILITY AFTER MIDNIGHT.  
 
GIVEN THE PROGRESSIVE NATURE OF THE SYSTEM, THE FLASH FLOOD THREAT  
WILL BE LOCALIZED AT BEST. HOWEVER, BROAD 1 TO 2 INCH RAINS OVER  
THE REGION MAY CAUSE A FEW RIVER POINTS TO FLOOD.  
 
THERE WILL BE A TEMPERATURE ROLLER COASTER NEXT WEEK WITH  
PRIMARILY TRANQUIL WEATHER. AFTER A MILD START TO THE WORK WEEK  
MONDAY, COOLER TEMPS ARE EXPECTED TUESDAY BEHIND A POLAR COLD  
FRONT WHICH WILL PUSH THRU MONDAY NIGHT. ANOTHER QUICK WARM-UP IS  
EXPECTED THRU THURSDAY AHEAD OF THE NEXT SYSTEM.  
 
THERE IS A LOT OF UNCERTAINTY REGARDING THE EVOLUTION OF THE UPPER  
FLOW PATTERN LATE NEXT WEEK AND INTO THE WEEKEND. ONE THING IS  
FAIRLY CERTAIN. SOME SHORTWAVE ENERGY IS EXPECTED TO DIVE  
SOUTHEAST ACROSS THE MIDDLE OF THE COUNTRY LATE NEXT WEEK AND WILL  
FORCE ANOTHER STRONG POLAR COLD FRONT THRU THE REGION. THE  
CANADIAN AND GFS KEEP THIS SYSTEM A PROGRESSIVE OPEN WAVE AND  
SUGGEST LITTLE IN THE WAY OF PRECIP FOR THE AREA. THE 00Z ECMWF IS  
FOLLOWING IN THE FOOTSTEPS OF THE 12Z RUN, CLOSING THE SYSTEM OFF  
WELL TO OUR WEST AND IS MUCH WETTER GOING INTO NEXT WEEKEND. GIVEN  
THE UNCERTAINTY, WILL KEEP THE CHANCE POPS FROM THE CONSENSUS  
GUIDANCE FOR FRIDAY WITH THE FRONT, AND WILL MAINTAIN LOW POPS  
GOING INTO THE WEEKEND. THE TEMPERATURE FORECAST IS NO WALK IN THE  
PARK EITHER DURING THIS TIME FRAME. STARTED WITH CONSENSUS  
FORECAST AND MADE ADJUSTMENTS.  
 
LACY  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
TUL 79 52 71 44 / 30 100 10 0  
FSM 78 59 70 46 / 20 100 40 10  
MLC 80 55 70 43 / 20 100 10 0  
BVO 77 50 72 38 / 60 100 10 0  
FYV 74 54 64 38 / 20 100 30 10  
BYV 74 55 65 44 / 20 100 40 10  
MKO 79 53 69 44 / 20 100 20 0  
MIO 77 51 68 43 / 10 100 20 0  
F10 79 53 70 45 / 20 100 10 0  
HHW 82 58 71 47 / 20 100 30 10  
 

 
   
TSA WATCHES/WARNINGS/ADVISORIES
 
 
OK...NONE.  
AR...NONE.  

 
 

 
 
AVIATION...20  
 
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