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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