680
FXUS63 KEAX 182347
AFDEAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
547 PM CST MON NOV 18 2024
KEY MESSAGES
- MORE RAIN, WIND CONDITIONS CONTINUE THIS EVENING
- MARGINAL SEVERE THUNDERSTORM RISK LATE THIS AFTERNOON
- MUCH COOLER THROUGH THE MIDDLE AND END OF THIS WEEK
DISCUSSION
ISSUED AT 130 PM CST MON NOV 18 2024
H5 TROUGH HAS ACQUIRED A NEGATIVE TILT WITH THE NOSE OF A 100+ KT
JET STREAK NOW ENTERING SOUTHERN KANSAS AS OF 18Z. SURFACE CYCLONE
IS CENTERED OVER CENTRAL TO EAST-CENTRAL KANSAS AND REMAINS IN AREA
OF VERY STRONG DCVA WHICH SHOULD ALLOW THE CYCLONE TO CONTINUE TO
STRENGTHEN AS WE HEAD INTO THE LATE AFTERNOON AND EARLY EVENING
HOURS. H5 HEIGHT FALLS CONTINUE WITH THE STRONG CVA ACROSS AREA.
SURFACE WARM FRONT HAS SURGED INTO SOUTHERN IOWA, WITH STRONG WAA
PROVIDING DEEP ISENTROPIC ASCENT THROUGHOUT AN AIRMASS WITH
DEWPOINTS IN THE LOWER 60S AND PWATS WELL ABOVE 1.5 INCHES. THIS
ACCOMPANIED WITH DIFFLUENCE ALOFT AROUND 300MB HAS PROVIDED THE LIFT
FOR THE WIDESPREAD PRECIPITATION SHIELD, AND HAS RESULTED IN HEAVY
RAINFALL WITH A WIDESPREAD HALF AN INCH TO THREE-QUARTERS OF AN
INCH, AND RADAR ESTIMATES SHOW SOME POCKETS IN EASTERN KANSAS OF
LOCALIZED 1.25 INCHES OF RAINFALL SO FAR. SHOWERS WILL CONTINUE, AND
AREAS MAY SEE ANOTHER ONE-HALF TO THREE-QUARTERS OF AN INCH OF QPF
BY THE END OF THIS EVENING. THE RAINFALL HAS BEEN VERY FAVORABLE, AS
THIS HELPS TO RELIEVE DROUGHT CONDITIONS ACROSS THE AREA, BUT COMING
AT A SLOW AND STEADY RATE TO LIMIT FLOODING ISSUES. SO FAR CREEKS
AND STREAMS, INCLUDING THOSE IN THE KC METRO, HAVE NOT SEEN A ROBUST
RESPONSE TO THE RAINFALL. WE WILL CONTINUE TO MONITOR HYDROLOGIC
CONDITIONS, BUT SO FAR THESE HAVE REMAINED UNDER CONTROL.
THE NEXT QUESTION IS ON THE SEVERE THREAT HEADING INTO THE
AFTERNOON. THE KINEMATIC FIELD THAT HAS BEEN ANTICIPATED THE PAST
FEW DAYS IS SHAPING UP. 0-6KM SHEAR IS ALREADY STARTING TO PEAK
ABOVE 60 KTS, WITH 0-1 KM SHEAR ABOVE 40 KTS IN MOST LOCATIONS. THE
DEEPENING SURFACE CYCLONE CONTINUES TO BACK SURFACE WINDS, AS WELL
AS INCREASE THE MAGNITUDE. ADDITIONAL PRECIPITATION DRAG HAS BROUGHT
SOME OF THAT INCREASED MOMENTUM TO THE SURFACE. 0-1KM SRH VALUES ARE
ALREADY ABOVE 300 M^2/S^2 ACROSS MOST OF THE REGION, AND REMAIN VERY
HIGH EVEN IN THE 0-500M LAYER. DEEPER SHOWERS HAVE BEEN TRYING TO
DEVELOP ALONG THE COLD FRONT IN EAST-CENTRAL KANSAS THIS AFTERNOON,
AND CAN BE SEEN ON THE DAY-CLOUD PHASE GOES-16 IMAGERY. HOWEVER, THE
PRECEDING PRECIPITATION FIELD AND STRATIFORM CLOUD COVER SO FAR HAVE
GREATLY LIMITED INSTABILITY. SOME ANALYSIS INDICATES MUCAPE VALUES
OF AROUND 250 J/KG, BUT SBCAPE AND 100MB MLCAPE VALUES REMAIN WELL
UNDER 100 J/KG HEADING INTO THE 19Z HOUR. IN ADDITION, NEARLY THE
ENTIRE COLUMN OF THE TROPOSPHERE HAS BEEN SATURATED, THERE IS NO EML
LIKE FEATURE ASSOCIATED WITH THIS SYSTEM, AND THEREFORE LAPSE RATES
IN BOTH THE BOUNDARY LAYER AND THE MID-LEVELS HAVE BEEN WEAK.
THEREFORE, IT WILL BE DIFFICULT TO GET CONVECTION IN THIS
THERMODYNAMIC SPACE. HOWEVER, THE CONTINUED LARGE SCALE SYNOPTIC
LIFT, THE NOSE OF THE JET STREAK, AND CONVERGENCE ALONG THE COLD
FRONT WILL PROVIDE PLENTY OF FORCING HEADING INTO THE EVENING, AND
IF ANY MINOR AMOUNTS OF INSTABILITY ARE REALIZED, CAN ALLOW
THUNDERSTORMS TO DEVELOP. WITH WINDS JUST ABOVE THE BOUNDARY ALREADY
ABOVE 50 KTS, A STRONGER THUNDERSTORM OR EVEN SHOWER WILL MAINTAIN
THE ABILITY TO BRING THAT MOMENTUM TOWARD THE SURFACE, PRODUCING
SEVERE WIND GUSTS. THIS WILL BE THE PRIMARY THREAT WITH ANY
CONVECTION OR STRONGER SHOWERS. HAIL IS NOT EXPECTED TO BE AN ISSUE
GIVEN THE WEAK INSTABILITY AND LACK OF CAPE THROUGH THE HAIL GROWTH
ZONE LAYER. IF DISCRETE STORMS DEVELOP, THEY WILL STRUGGLE TO BECOME
TEXTBOOK SUPERCELLS DUE TO THE WEAK INSTABILITY. HOWEVER,
ENVIRONMENT SURFACE VORTICITY WILL REMAIN STRONG WITH THE LOW-LEVEL
WIND SHEAR AND CURVED HODOGRAPHS AS THE CYCLONE APPROACHES. COMBINED
WITH VERY LOW LCLS OF JUST A FEW HUNDRED METERS, THIS COULD RESULT
IN VORTICITY STRETCHING WITH ANY MODEST UPDRAFTS THAT ARE ABLE TO
OVERCOME THE WEAK INSTABILITY, AND MAY PRODUCE A SHORT-LIVED WEAK
TORNADO. FROM A SYNOPTIC PATTERN STANDPOINT, THIS 500MB COLD-CORE
LOW IS A RATHER TYPICAL WEAK TORNADO PRODUCER, ESPECIALLY FOR AREAS
ALONG THE COLD FRONT, OR, ALONG THE TRIPLE POINT SHOULD THE CYCLONE
BECOME OCCLUDED IN THE NEXT FEW HOURS. THIS WILL NOT BE THE BIGGEST
HAZARD WITH STORMS, BUT STORMS COULD FORM SHORT-LIVED, WEAK
TORNADOES. AGAIN, THE BIGGEST HAZARD WITH STORMS AND STRONGER
SHOWERS WILL BE WIND GUSTS AT THE SURFACE OVER 50 KTS (58 MPH). IS
THERE COMPLETE BUST POTENTIAL WHERE NO THUNDERSTORMS DEVELOP? YES,
THE TROPOSPHERE COULD REMAIN TOO STABLE TO INITIATE CONVECTION. IF
THERE IS NO NOTABLE THUNDERSTORMS PRIOR TO SUNSET, INITIATION
POTENTIAL BECOMES UNLIKELY. THEREFORE, THE MENTIONED DETAILS ABOVE
ARE ALL VERY CONDITIONAL. THE FRONT SHOULD CLEAR THE AREA BETWEEN
04Z-06Z TIME FRAME, WITH ANY MAIN CONVECTIVE LINE (IF IT DEVELOPS)
EXITING THE AREA, THOUGH LINGERING SHOWERS MAY BE POSSIBLE IN A
SECONDARY SURFACE TROUGH AXIS THAT FOLLOWS BEHIND THE COLD FRONT, AS
MID-LEVEL HEIGHT RISES LOOK TO BE SLOW TO START. IN ADDITION,
STRONGER PRESSURE GRADIENT MAY MAINTAIN BREEZY WINDS HEADING INTO
THE OVERNIGHT HOURS.
THE TROUGH LIFTS NORTHWARD AND THE BULK OF THE STRONGER JET STREAK
AND OTHER ROBUST KINEMATICS EXIT THE AREA, BUT THE SYSTEM IS PROGGED
TO BECOME A CLOSED-LOW SYSTEM AND VERTICALLY STACKS WITH THE SURFACE
LOW AS IT GETS INTO THE NORTHERN PLAINS AND WESTERN GREAT LAKES
REGION. THERE IS A STRONGER PV ANOMALY THAT WILL PROMOTE TROUGHING
JUST OFF THE PACIFIC NORTHWEST COAST WITH RIDGING OVER THE NORTHERN
ROCKIES. THIS PATTERN WILL FORCE VERY COLD AIR ACROSS THE NORTHERN
PLAINS AND GRADUALLY WORKS TOWARD THE LOWER MISSOURI RIVER VALLEY
TUESDAY THROUGH THE MIDDLE OF THIS WEEK. THIS WILL BRING
SUBSTANTIALLY COOLER TEMPERATURES THIS WEEK, WITH HIGHS IN THE UPPER
40S TO LOWER 50S IN THE AFTERNOON, AND EARLY MORNING LOWS DROPPING
INTO THE UPPER 20S FOR MUCH OF THE FORECAST AREA. THERE WERE SIGNALS
IN MODEL RUNS OVER THE WEEKEND FOR POSSIBLE SNOW FLURRY ACTIVITY IN
SOME PARTS OF THE FORECAST AREA TOWARD THE MIDDLE END OF THIS WEEK,
BUT RECENT RUNS HAVE SHOWN A DECREASING TREND. HOWEVER, AS THE
STRONG CAA TAKES PLACE, IF THERE IS ENOUGH MOISTURE WE STILL MAY BE
ABLE TO DEVELOP A FEW FLURRIES, BUT THE LACK OF MOISTURE KEEPS
OVERALL QPF EXTREMELY LOW AND THUS NO ACCUMULATIONS ARE CURRENTLY IN
THE FORECAST. WE ARE STILL LOOKING AT LESS THAN 30 PERCENT
PROBABILITIES FOR EXCEEDING 50F BEFORE NEXT WEEKEND, WITH OVER 80
PERCENT PROBABILITIES OF DROPPING BELOW 30F DURING THE EARLY MORNING
HOURS.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 537 PM CST MON NOV 18 2024
MOST OF THE SHOWERS HAVE MOVED EAST OF THE TERMINALS EARLY THIS
EVENING, BUT A FINAL BAND OF SHOWERS AND A COUPLE OF EMBEDDED
THUNDERSTORMS WILL APPROACH FAR NORTHEAST KANSAS AND NORTHWEST
MISSOURI AFTER 01Z. OBSERVATIONS UPSTREAM (AND PRIMARILY AFTER
THE CONVECTIVE BAND MOVES THROUGH) HAVE CONSISTENTLY INDICATED
50 TO 60 MPH GUSTS IN CENTRAL/SOUTH-CENTRAL KANSAS. THUS, AFTER
THE CONVECTIVE BAND MOVES THROUGH THE TAF SITES, EXPECT WIND
DIRECTIONS TO VEER TO SOUTHWESTERLY, WITH WINDS AT LEAST
INCREASING TO 20 TO 30 KT WITH GUSTS TO 40 KT FOR A COUPLE
HOURS. AN ISOLATED/BRIEF HIGHER GUST CANNOT BE RULED OUT, BUT
CONFIDENCE IS LOW ON WHERE/WHEN. FOR NOW, HAVE KEPT MENTION OF
THUNDER OUT OF THE TAFS, BUT WILL MONITOR THE BAND OF SHOWERS
CLOSELY TO DETERMINE IF TS MENTION IS NEEDED VIA AMENDMENTS. DURING
THE OVERNIGHT, WINDS SHOULD CONTINUE TO VEER, BECOMING MORE
WESTERLY BY DAYBREAK TUESDAY, AS SPEEDS/GUSTS GRADUALLY
DIMINISH. ON TUESDAY, WEST TO NORTHWEST WINDS AROUND 10 KT WITH
OCCASIONAL GUSTS TO 20 KT ARE ANTICIPATED.
REGARDING FLIGHT CATEGORIES, VARIATIONS BETWEEN VFR AND MVFR ARE
EXPECTED THIS EVENING, PARTICULARLY THROUGH 03Z, BEFORE
PREDOMINANT VFR TAKES HOLD OVERNIGHT. VFR CONDITIONS ARE QUITE
LIKELY ON TUESDAY (>95 PERCENT CHANCE).
EAX WATCHES/WARNINGS/ADVISORIES
MO...WIND ADVISORY UNTIL 9 PM CST THIS EVENING FOR MOZ020-021-
028>030-037-038-043>045-053-054.
KS...WIND ADVISORY UNTIL 9 PM CST THIS EVENING FOR KSZ025-057-060-
102>105.
DISCUSSION...KRULL
AVIATION...CMS
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