757  
FXUS64 KAMA 211128  
AFDAMA  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE AMARILLO TX  
628 AM CDT SUN OCT 21 2018  
   
AVIATION
 
 
12Z TAF ISSUANCE...VFR CONDITIONS ARE EXPECTED THROUGH THE TAF  
PERIOD. SOUTHWEST WINDS WILL PREVAIL AT ALL THREE TAF SITES AND  
SKIES WILL REMAIN SKC/FEW. WINDS WILL BE GUSTY UP TO 25-30 KTS BY  
17Z FOR ALL THREE TAF SITES AND WILL DIMINISH OVERNIGHT SUNDAY.  
 
RUTT  
 

 
   
PREV DISCUSSION
 
/ISSUED 432 AM CDT SUN OCT 21 2018/  
 
SHORT TERM...  
AS THE SURFACE HIGH PRESSURE MOVES TOWARDS THE OHIO VALLEY,  
SOUTHWESTERLY WINDS AND WARM TEMPERATURES REMAIN FOR SUNDAY. HIGH  
TEMPERATURES WILL BE IN THE UPPER 60'S AND LOW 70'S, BUT A FEW HIGH  
CIRRUS MAY CREEP INTO THE PANHANDLES BY THE EARLY AFTERNOON AND  
IMPACT HIGH TEMPERATURES BY A DEGREE OR TWO. A LEE-SIDE LOW  
FORMING OFF THE ROCKIES WILL TIGHTEN THE SURFACE PRESSURE GRADIENT  
OVER THE PANHANDLES AND BRING GUSTY WINDS IN THE EARLY AFTERNOON  
HOURS. THE MENTION OF POPS HAVE BEEN REMOVED FROM THE FORECAST  
DUE TO MODEL AGREEMENT IN THE WEAK 500 MB DISTURBANCE REMAINING  
SOUTH OF OUR CWA. WINDS SPEEDS WILL DIMINISH OVERNIGHT SUNDAY AND  
SKIES WILL CLEAR GIVING WAY TO MORNING LOWS IN THE 40'S.  
 
LONG TERM...  
CURRENTLY WATCHING OUR NEXT WEATHER MAKER DEPICTED AS A CLOSED  
UPPER LOW OFF THE COAST OF CA VIA LATEST GOES IMAGERY. THIS  
CLOSED LOW IS EXPECTED TO SLOWLY DRIFT OUT OVER THE SOUTHERN GREAT  
BASIN AS IT BROADENS AND BECOMES AN OPEN WAVE AMIDST SPLIT FLOW  
ACROSS THE CONUS. DETERMINISTIC MODELS SUGGEST SEVERAL SHORTWAVES  
WILL ROUND THE BASE OF THE PARENT TROUGH MONDAY THROUGH WEDNESDAY.  
THE MONDAY WAVE LOOKS WEAK AND MOISTURE STARVED, SO NOT EXPECTING  
MUCH MORE THAN PERHAPS A MINOR INCREASE IN MID/UPPER CLOUDS.  
MEANWHILE, A SURFACE RIDGE WILL BE SHIFTING INTO THE SOUTHEAST  
CONUS AS A PRE-FRONTAL SURFACE TROUGH TRIES TO PUSH INTO THE  
NORTHERN PANHANDLES. TEMPERATURES MIGHT BE TRICKY DEPENDING ON HOW  
FAR SOUTH THIS SURFACE TROUGH ADVANCES MONDAY, WITH TEMPERATURES  
BEING QUITE WARM SOUTH OF THE SFC BOUNDARY AND MORE MILD NORTH.  
 
THE SECOND MORE POTENT MID/UPPER SHORTWAVE WILL DIG A BIT FURTHER  
SOUTH AND TAP INTO SOME TROPICAL MOISTURE ASSOCIATED WITH  
TROPICAL STORM WILLA ALONG WITH MOISTURE FROM THE BAJA REGION  
TUESDAY INTO WEDNESDAY. THE 500MB WAVE IS PROGGED TO STRENGTHEN  
AS IT CROSSES THE SOUTHERN/CENTRAL ROCKIES TUESDAY NIGHT. AS PAR  
FOR THE COURSE, THE GFS IS THE MOST PROGRESSIVE WITH THIS FEATURE  
AND SLIGHTLY FURTHER NORTH COMPARED TO THE ECMWF/CANADIAN. AT THIS  
TIME AND BASED ON RECENT MODEL PERFORMANCE, TRENDED POPS MORE  
TOWARDS THE ECMWF KEEPING PRECIP CHANCES AROUND A BIT LONGER  
WEDNESDAY. ANOTHER INTERESTING FEATURE SHOWING UP IN THE MODELS IS  
NEGATIVE THETA-E AIR AROUND 800MB-850MB BEING ADVECTED WESTWARD  
WHILE 700MB TO 500MB MOISTURE INCREASES SUBSTANTIALLY TUESDAY.  
THIS DRY 850MB AIR COULD HAMPER PRECIP IN THE EASTERN HALF OF THE  
AREA AT LEAST UNTIL TUESDAY NIGHT WHEN THE COLUMN IS FINALLY ABLE  
TO MOISTEN WITH LSA SPREADING ACROSS THE AREA IN CONJUNCTION WITH  
LEFT EXIT REGION OF UPPER LEVEL JET AND INCREASED 500MB POS  
VORTICITY ADVECTION. ULTIMATELY, IT APPEARS THE WESTERN HALF OF  
THE PANHANDLES WILL FAIR BEST ON PRECIP AMOUNTS WITH HALF INCH TO  
ONE INCH VALUES BEING POSSIBLE (LOCALIZED HIGHER), WITH VALUES  
DROPPING OFF FURTHER EAST. PRECIPITABLE WATER VALUES LOOK TO  
MAXIMIZE LATE TUESDAY NIGHT INTO WEDNESDAY MORNING WITH MOST OF  
THE AREA SEEING 90TH PERCENTILE OR GREATER. FLOODING CONCERNS ARE  
NOT TOO HIGH AT THIS TIME, ESPECIALLY GIVEN LACK OF INSTABILITY  
AND DETERMINISTIC/ENSEMBLE QPF AMOUNTS. HOWEVER, GIVEN RECENT  
RAINS AND HIGHER PWATS, CAN'T RULE OUT SOME MINOR FLOODING IN  
LOCALIZED AREAS. ALSO, KEPT THUNDER OUT OF FORECAST WITH VERY LOW  
TO NO INSTABILITY EXPECTED. PRECIP SHOULD END ACROSS THE WEST  
FIRST ON WEDNESDAY AFTERNOON, WITH THE AREA BEING DRY BY WEDNESDAY  
EVENING.  
 
HIGH TEMPERATURES WILL BE BELOW AVERAGE FOR BOTH TUESDAY AND  
WEDNESDAY GIVEN THE CLOUD COVER AND SHOWERS. A WARMING TREND IS  
EXPECTED INTO FRIDAY, WITH DRIER CONDITIONS AS ZONAL FLOW SETS UP.  
MODEL DIFFERENCES EXIST WITH A POTENTIAL COLD FRONT ON SATURDAY,  
AS THE AREA GOES INTO A PERIOD OF NORTHWEST FLOW ON THE EDGE OF A  
BROAD BUT PROGRESSIVE UPPER TROUGH DEVELOPING OVER THE EASTERN  
CONUS. THINGS COULD GET INTERESTING GOING INTO NEXT WEEK WITH THE  
LATEST 00Z GFS SUGGESTING ALMOST A MCFARLAND TYPE PATTERN SETTING  
UP. ECMWF NOT QUITE AS EXCITED, BUT STILL WORTH WATCHING AS WE  
APPROACH HALLOWEEN.  
 
WARD  
 

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

 
 

 
 
23/7  
 
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