401  
FXUS64 KOUN 140355  
AFDOUN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORMAN OK  
955 PM CST WED DEC 13 2017  
   
AVIATION
 
 
TAFS 1406/1506...  
 
HIGH AND MID CLOUDS WILL DEVELOP AHEAD OF A SHORTWAVE  
TROUGH TONIGHT AND THURSDAY, ESPECIALLY ACROSS THE NORTHERN  
HALF OF OKLAHOMA. A LIGHT TO MODERATE NORTHERLY WIND WILL  
PREVAIL OVER THE NEXT 18-24 HOURS.  
 

 
   
PREV DISCUSSION
 
/ISSUED 601 PM CST WED DEC 13 2017/  
 
AVIATION...  
TAFS 1400/1424...  
 
VARIABLE HIGH CLOUDS WILL MOVE OVER OKLAHOMA AND NORTH  
TEXAS THROUGH THE TAF PERIOD. A LIGHT NORTHERLY WIND WILL PREVAIL  
TONIGHT AND WILL INCREASE IN SPEED ON THURSDAY.  
 
PREV DISCUSSION... /ISSUED 252 PM CST WED DEC 13 2017/  
 
DISCUSSION...  
IMPACTFUL WEATHER OVER THE NEXT SEVERAL DAYS IS CENTERED AROUND  
FIRE WEATHER. ALTHOUGH, THE WEATHER/FUEL ENVIRONMENT DOES NOT  
CURRENTLY SEEM TO SUPPORT SIGNIFICANT FIRE WEATHER CONCERN (SEE  
DETAILS IN FIRE WEATHER SECTION BELOW). OTHERWISE, TEMPERATURES  
WILL BE NORMAL TO OCCASIONALLY ABOVE NORMAL FOR MID-DECEMBER. ONE  
LOW-MEDIUM PROBABILITY PRECIPITATION OPPORTUNITY WILL OCCUR FOR  
MAINLY EASTERN PORTIONS OF THE AREA SATURDAY NIGHT INTO SUNDAY  
MORNING. CHANGES TO THE PREVIOUS FORECAST WERE MINIMAL.  
 
WITHIN NORTHWESTERLY FLOW ACROSS THE MIDDLE PART OF THE COUNTRY, A  
WEAK SHORTWAVE IS PASSING THROUGH. A BAND OF CIRRUS ACROSS NORTHERN  
OKLAHOMA EARLY THIS AFTERNOON IS COINCIDENT WITH WEAK ASCENT  
ASSOCIATED WITH THIS SHORTWAVE. THIS WAVE HAS SENT A COLD FRONT INTO  
THE AREA TODAY RESULTING IN AN INCREASE IN GUSTY NORTHERLY WINDS AS  
IT PASSES.  
 
THERE HAVE BEEN A FEW REPORTS FROM NORTHWEST OKLAHOMA OF SOME SMOKE  
AND THIS DOESN'T APPEAR TO BE DUE TO ANY LOCAL WILDFIRE ACTIVITY,  
RATHER MODIS SATELLITE SUGGESTS IT IS PROBABLY FROM THE LEGION LAKE  
FIRE IN THE BLACK HILLS OF SOUTH DAKOTA.  
 
A MORE INTENSE SHORTWAVE TROUGH WILL MOVE THROUGH TOMORROW FORCING A  
MORE SIGNIFICANT COLD SURGE INTO THE AREA EARLY IN THE DAY. HIGH  
TEMPERATURES ARE EXPECTED TO BE AROUND 15 DEGREES COLDER.  
 
LATEST MODEL RUNS SHOW A PERSISTENT TROUGH IN THE EAST AND  
DIMINISHING REX BLOCK PATTERN WITH SLOWLY DEAMPLIFYING RIDGE IN THE  
WEST THROUGH THE END OF THE WEEK. THIS WILL SUPPORT A CONTINUATION  
OF DRY NORTHWESTERLY FLOW ALOFT ACROSS OUR REGION. NOTABLE CHANGES  
ON THE SYNOPTIC SCALE OCCUR BY SATURDAY. A CLOSED LOW, NOW OVER  
NORTHERN BAJA CALIFORNIA, WILL OPEN UP AND EJECT NORTHEASTWARD IN  
RESPONSE TO DEEPENING LONGWAVE TROUGH IN THE WEST. DESPITE PWAT  
VALUES BEING SIGNIFICANTLY BELOW NORMAL NOW ACROSS TEXAS INTO THE  
WESTERN GULF, MODEST MOISTURE RETURN WILL OCCUR QUICKLY IN  
RESPONSE TO THIS LEAD SHORTWAVE AND SHOULD BE ENOUGH FOR SOME  
SHOWERS ACROSS ROUGHLY THE EASTERN TWO-THIRDS OF THE AREA SATURDAY  
NIGHT THROUGH EARLY SUNDAY. INSTABILITY WILL BE VERY WEAK AT  
BEST, POSSIBLY SUPPORTING A FEW WEAK THUNDERSTORMS AS WELL.  
 
EASTWARD PROGRESSION OF THIS LONGWAVE IS WHERE UNCERTAINTIES ARISE.  
DETERMINISTIC GUIDANCE IS AS MUCH AS 24 HOURS OUT OF PHASE.  
GENERALLY, ECMWF AND ITS ENSEMBLE MEAN ARE MUCH QUICKER THAN THE GFS  
AND MOST OF ITS ENSEMBLES. IF THE GFS/GEFS IS RIGHT, THIS COULD  
OFFER ANOTHER LOW PROBABILITY PRECIPITATION EVENT FOR THE EASTERN  
PORTIONS OF THE AREA SOMETIME AROUND MONDAY, BUT WE HAVE KEPT THE  
FORECAST DRY FOR NOW GIVEN SIGNIFICANT UNCERTAINTY.  
 
BRB  
 
FIRE WEATHER...  
SOME FIRE ACTIVITY WILL REMAIN POSSIBLE THROUGH THIS AFTERNOON.  
LATEST OKLAHOMA MESONET OBSERVATIONS SHOW RELATIVE HUMIDITY  
VALUES AROUND OR BELOW 20 PERCENT FOR MOST OF THE AREA, AND AROUND  
10-15 MPH NORTHERLY WINDS BEHIND THE SOUTHWARD MOVING COLD FRONT.  
THIS IS RESULTING IN ELEVATED TO NEAR CRITICAL FIRE WEATHER  
CONDITIONS.  
 
AS MENTIONED ABOVE, A SMOKE SMELL MAY OCCUR BEHIND THE COLD FRONT  
MOVING THROUGH THE STATE NOW. THIS SMOKE SEEMS TO BE ORIGINATING  
FROM THE LEGION LAKE FIRE IN THE BLACK HILLS.  
 
LATEST SHORTWAVE BAND SATELLITE IMAGERY REVEALS ONE HOTSPOT AND  
PROBABLE FIRE IN WESTERN LOVE COUNTY. LOCAL MEDIA REPORTS AND KTLX  
RADAR INDICATE A MINOR FIRE IN SOUTH OKC. NO OTHER ONGOING  
ACTIVITY IS KNOWN AT THIS TIME, BUT ADDITIONAL INITIAL ATTACK  
ACTIVITY IS CERTAINLY POSSIBLE THROUGH THE AFTERNOON.  
 
COOLER TEMPERATURES AND COMPARATIVELY HIGHER RELATIVE HUMIDITY  
SHOULD LIMIT FIRE CONCERNS TOMORROW, AND ALTHOUGH HUMIDITY WILL BE  
LOWER FRIDAY, WINDS SHOULD REMAIN FAIRLY LIGHT. THE NEXT FIRE  
WEATHER DAY IS EXPECTED TO BE SATURDAY WHEN GUSTY SOUTHERLY WINDS  
BEGIN BEFORE A SURGE OF LOW LEVEL MOISTURE ARRIVES. ELEVATED FIRE  
WEATHER CONDITIONS MAY RESULT. LATEST ERC-G VALUES IN WESTERN  
OKLAHOMA WHERE NEAR OR SLIGHTLY ABOVE THE 90TH PERCENTILE WHICH  
WOULD TEND TO ENHANCE FIRE ACTIVITY EVEN IF ONLY MARGINAL  
METEOROLOGICAL CONDITIONS ARE REALIZED.  
 
BRB  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
OKLAHOMA CITY OK 35 47 30 51 / 0 0 0 0  
HOBART OK 33 50 27 54 / 0 0 0 0  
WICHITA FALLS TX 34 53 31 54 / 0 0 0 0  
GAGE OK 29 49 23 56 / 0 0 0 0  
PONCA CITY OK 32 47 28 51 / 0 0 10 0  
DURANT OK 36 53 34 54 / 0 0 0 0  
 

 
   
OUN WATCHES/WARNINGS/ADVISORIES
 
 
OK...NONE.  
TX...NONE.  

 
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab OK Page
The Nexlab TX Page Main Text Page