383
FXUS64 KOUN 170959
AFDOUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
359 AM CST SUN NOV 17 2024
..NEW SYNOPSIS, NEAR TERM, SHORT TERM, LONG TERM
KEY MESSAGES
UPDATED AT 359 AM CST SUN NOV 17 2024
- HEAVY RAINFALL IS LIKELY LATE TODAY INTO MONDAY
- SEVERE STORM LIKLIHOOD INCREASING FOR EARLY MONDAY WITH QLCS
TORNADOES POSSIBLE.
- TURNING COOLER TOWARDS THE MIDDLE OF NEXT WEEK.
SYNOPSIS
ISSUED AT 359 AM CST SUN NOV 17 2024
THIS IS DEFINITELY A FORECAST WHERE THE FORECAST GRIDS ARE ONE
THING, BUT THE LARGER CONTEXT WILL BE WHAT IS IMPORTANT.
WIDESPREAD RAINFALL IS EXTREMELY LIKELY WITH LOCALLY HEAVY
RAINFALL FLOODING CERTAINLY POSSIBLE. MORE UNCERTAIN IS THE SEVERE
WEATHER AND TORNADO POTENTIAL, BUT A LOT OF PARAMETERS ARE VERY
HIGH END ON THE CLIMATOLOGICAL DISTRIBUTION SO THERE IS DEFINITELY
SOME POTENTIAL.
WITH THE POTENTIAL FOR OVERNIGHT SEVERE WEATHER AND POSSIBLY
TORNADOES, IT WILL BE IMPORTANT FOR PEOPLE TO HAVE WAYS TO
RECEIVE WARNINGS OVERNIGHT AND BE PREPARED TO TAKE ACTION QUICKLY.
BIG PICTURE, THE LARGE UPPER LEVEL STORM SYSTEM NEAR THE
CALIFORNIA-ARIZONA-MEXICO BORDER WILL MOVE ACROSS NORTHERN SONORA
AND CHIHUAHUA AND THEN MOVE NORTHEAST THROUGH SOUTHWEST TEXAS AND
INTO NORTHWESTERN OKLAHOMA BY AROUND NOON ON MONDAY. WIDESPREAD
SHOWERS AND STORMS WILL DEVELOP AHEAD OF THIS SYSTEM AFFECTING THE
AREA, THIS AFTERNOON THROUGH MONDAY.
NEAR TERM
(TODAY THROUGH MONDAY)
ISSUED AT 359 AM CST SUN NOV 17 2024
LOOKING AT THE POTENTIAL HAZARDS TODAY...
HEAVY RAINFALL/FLOODING...
LOCALIZED HEAVY RAINFALL IS EXPECTED, ESPECIALLY OVERNIGHT AND
EARLY MONDAY. FORECAST PRECIPITABLE WATER VALUES AROUND 09Z ARE
EXTREME FOR THIS TIME OF YEAR WITH BOTH NAM AND GFS FORECASTING
WIDESPREAD 1.5 INCHES WITH LOCALIZED 1.8 TO 1.9 INCHES. FOR
REFERENCE, THE HIGHEST NOVEMBER PW VALUE MEASURED IN AN
OKC/OUN/TIK SOUNDING IS 1.61 SINCE 1948 PER SPC SOUNDING
CLIMATOLOGY. WITH THIS, STORMS WILL BE VERY EFFICIENT WITH RAIN
PRODUCTION. AVERAGE RAINFALL VALUES FROM WPC SHOW A WIDESPREAD
AREA OF 2 TO 3 INCHES ACROSS WESTERN, CENTRAL AND NORTHERN
SECTIONS OF THE AREA, BUT LOCALIZED 5 TO 6 INCHES WILL BE
POSSIBLE. SOME OF THE MODELS DO NOW PLACE THE HEAVY RAIN AXIS TO
INCLUDE AREAS FARTHER WEST, AND WITH THAT WE HAVE EXPANDED THE
FLOOD WATCH WEST TO INCLUDE ALL BUT HARPER COUNTY. THE FLOOD WATCH
IS VALID UNTIL 6 PM MONDAY EVENING, BUT IT IS LIKELY THAT WE WILL
BE ABLE TO CANCEL PORTIONS EARLY FROM WEST TO EAST AS THE DRY
SLOT MOVES IN AND PRECIPITATION MOVES OUT.
SEVERE WEATHER/TORNADO POTENTIAL...
THIS IS MORE UNCERTAIN AND WILL BE DEPENDENT ON HOW MUCH
INSTABILITY CAN DEVELOP. BUT IT WILL NOT TAKE MUCH INSTABILITY TO
POTENTIALLY CAUSE PROBLEMS. WIND SHEAR VALUES ARE EXTREME GIVEN
THE 65 TO 75 KNOT 850 MB JET AXIS AND THE 105 TO 100 KNOT 500 MB
JET AXIS DEVELOPING AND MOVING INTO THE AREA BETWEEN 06Z AND 18Z.
(AGAIN, FOR REFERENCE THE HIGHEST 850 MB NOVEMBER WINDS MEASURED
IN AN OKC/OUN/TIK SOUNDING IN NOVEMBER HAS BEEN 65 KNOTS SINCE
1948, AND THE FORECAST 500 MB WINDS ARE NOT QUITE AS UNCOMMON, BUT
DEFINITELY ON THE EXTREME END OF THE DISTRIBUTION).
THE SEVERE WEATHER AND TORNADO THREAT WILL BE HIGHEST WITH A
SQUALL LINE THAT IS EXPECTED TO DEVELOP WEST OF THE AREA AROUND
MIDNIGHT TONIGHT AND THEN MOVE INTO AT LEAST SOUTHWESTERN OKLAHOMA
AND WESTERN NORTH TEXAS. THE NORTHERN EDGE OF THE INTENSE PART OF
THE SQUALL LINE IS SOMEWHAT UNCERTAIN AND DEPENDS ON HOW FAR NORTH
THE WARM FRONT LIFTS ALLOWING WHATEVER INSTABILITY WE HAVE TO
SPREAD NORTH.
WITH THE MERIDIONAL FLOW THROUGH MUCH OF THE ATMOSPHERE, THE WIND
SHEAR VECTORS DO NECESSARILY LOOK IDEAL RELATIVE TO THE EXPECTED
NORTH-SOUTH ORIENTATION OF THE SQUALL LINE FOR QLCS TORNADOES.
BUT SOME RECENT QLCS EXAMPLES SHOW THAT THIS MAY NOT BE ENOUGH TO
PREVENT QLCS TORNADO DEVELOPMENT (SUCH AS OCTOBER 9 2018 AS ONE
EXAMPLE). AND THERE IS ENOUGH BACKED LOW-LEVEL FLOW FORECAST THAT
THE SHEAR VECTOR ORIENTATION MIGHT NOT BE COMPLETELY PARALLEL TO
THE SQUALL LINE, ESPECIALLY VERY EARLY MONDAY MORNING AS SURFACE
CYCLOGENESIS IS DEVELOPING SOMEWHERE IN THE VICINITY OF CHILDRESS.
AGAIN THERE IS SOME QUESTION ON INSTABILITY, SO THE TORNADO
POTENTIAL IS NOT A GUARANTEE, BUT THERE IS ENOUGH POTENTIAL TO BE
CONCERNED ABOUT, ESPECIALLY WITH THE EXTREME WIND SHEAR EXPECTED
OVERNIGHT INTO TOMORROW.
COLD-CORE THUNDERSTORM POTENTIAL NORTHWEST...
THIS SCENARIO HAS EVEN MORE UNCERTAINTY, BUT WITH THE UPPER LOW
TRACKING OVER NORTHWEST OKLAHOMA LATE MONDAY MORNING AND EARLY
AFTERNOON, THE COLD MID-LEVEL TEMPERATURES WILL POTENTIALLY ALLOW
ENOUGH INSTABILITY FOR SHOWERS AND THUNDERSTORMS TO DEVELOP NEAR
UPPER-LOW CENTER, AND THERE COULD BE SOME POTENTIAL FOR SEVERE
WEATHER LATE MONDAY MORNING/AFTERNOON IN THE NORTHWEST WITH THIS
DEPENDING ON THE SURFACE PATTERN AND HOW MUCH INSTABILITY CAN
DEVELOP. WITH ENOUGH INSTABILITY, WE COULD NOT COMPLETELY RULE OUT
A TORNADO IN THIS AREA EITHER, ALTHOUGH THE PROBABILITY IS LOW.
/SPEG
SHORT TERM
(MONDAY NIGHT THROUGH TUESDAY NIGHT)
ISSUED AT 359 AM CST SUN NOV 17 2024
THE SHOWERS AND STORMS ARE EXPECTED TO HAVE MOVED OUT BY SUNSET
MONDAY, SO MUCH CALMER WEATHER IS EXPECTED MONDAY NIGHT AND
TUESDAY. TEMPERATURES WILL BE A LITTLE COOLER THANKS TO THE COLD
FRONT THAT IS BROUGHT IN WITH MONDAY'S STORM SYSTEM.
LONG TERM
(WEDNESDAY THROUGH SATURDAY)
ISSUED AT 359 AM CST SUN NOV 17 2024
THE WEDNESDAY/THURSDAY STORM SYSTEM MOVING SOUTHEAST FROM CENTRAL
CANADA IS NOW FORECAST BY MOST MODELS TO BE FARTHER NORTHEAST -
MOVING INTO THE MIDWEST/GREAT LAKES REGION. WITH THIS FORECAST
PATH, PRECIPITATION CHANCES HAVE BEEN REMOVED FROM NORTHERN
OKLAHOMA WITH THIS PACKAGE. OF COURSE WE WILL STILL WATCH THE
MODEL TRENDS. BUT THE COLD AIR MOVING DOWN THE PLAINS BEHIND THIS
STORM SYSTEM WILL BRING SOME COOL TEMPERATURES MID TO LATE WEEK.
FREEZING TEMPERATURES WILL BE POSSIBLE NORTHWEST ON THURSDAY
MORNING AND POTENTIALLY ACROSS MORE OF THE AREA ON FRIDAY MORNING.
AVIATION
(06Z TAFS)
ISSUED AT 1100 PM CST SAT NOV 16 2024
MVFR CEILINGS WILL DEVELOP OVER PARTS OF THE FORECAST AREA, MOST
NOTABLY SOUTHEAST OKLAHOMA, THIS MORNING. A FEW SITES ALONG THE I-35
CORRIDOR MAY EVEN SEE SOME BRIEF IFR CEILINGS. RAIN WITH LOW CHANCES
FOR THUNDER WILL GRADUALLY SPREAD OVER THE FORECAST AREA FROM THE
SOUTHWEST THIS AFTERNOON. CEILINGS WILL THEN CRASH TONIGHT, WITH
WIDESPREAD IFR (POSSIBLY LIFR) POSSIBLE.
DAY
PRELIMINARY POINT TEMPS/POPS
OKLAHOMA CITY OK 70 61 67 45 / 40 100 90 0
HOBART OK 68 55 66 41 / 70 100 60 0
WICHITA FALLS TX 74 62 70 46 / 40 100 60 0
GAGE OK 64 49 61 36 / 20 100 80 0
PONCA CITY OK 70 59 68 42 / 30 100 100 0
DURANT OK 76 62 71 48 / 20 100 100 0
OUN WATCHES/WARNINGS/ADVISORIES
OK...FLOOD WATCH FROM THIS EVENING THROUGH MONDAY AFTERNOON FOR
OKZ005>031-033>040-044-045.
TX...FLOOD WATCH FROM THIS EVENING THROUGH MONDAY AFTERNOON FOR
TXZ083>090.
NEAR TERM...26
SHORT TERM...26
LONG TERM....26
AVIATION...14
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