901
FXUS63 KEAX 152013
AFDEAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
213 PM CST FRI NOV 15 2024
KEY MESSAGES
- WARM AND BREEZY CONDITIONS ARE EXPECTED ON SATURDAY. A STRAY
SHOWER (OR STORM) MAY DEVELOP (30 PERCENT CHANCE) NORTHWEST OF
I-35 DURING THE AFTERNOON OR EVENING, BUT NO HAZARDOUS WEATHER
IS EXPECTED.
- A SOAKING RAIN EVENT IS STILL EXPECTED SUNDAY NIGHT THROUGH
MONDAY, WITH HIGH (>70 PERCENT) PROBABILITIES OF ONE OR MORE
INCHES OF RAIN BY TUESDAY MORNING. THUNDERSTORMS MAY ALSO
OCCUR ON MONDAY (20 PERCENT CHANCE), WITH A STRONG/SEVERE
STORM NOT OUT OF THE QUESTION MONDAY AFTERNOON.
- TWO PERIODS OF WINDY CONDITIONS ARE APPARENT. THE FIRST IS ON
MONDAY, WITH >50 PERCENT CHANCES OF WIND GUSTS EXCEEDING 40
MPH. THE SECOND IS ON WEDNESDAY, WITH >40 PERCENT
PROBABILITIES OF 40+ MPH WIND GUSTS.
- MUCH COLDER WEATHER IS EXPECTED WEDNESDAY AND THURSDAY, WITH
HIGHS IN THE 40S AND LOWS IN THE 20S.
DISCUSSION
ISSUED AT 112 PM CST FRI NOV 15 2024
PRIMARY FORECAST CONCERNS REMAIN THE RAINFALL EVENT SUNDAY NIGHT
THROUGH MONDAY NIGHT, AND THE POTENTIAL FOR STRONG WINDS/GUSTS
AS THE ATTENDANT STORM SYSTEM APPROACHES THE AREA ON MONDAY AND
AS MUCH COLDER AIR IN ITS WAKE ENVELOPS THE REGION ON WEDNESDAY.
AMPLIFIED UPPER-AIR PATTERN IS WELL-ESTABLISHED ACROSS NORTH
AMERICA TODAY, AS A DEEP TROUGH IS MOVING INTO/THROUGH THE
INTERIOR WEST, A DIGGING TROUGH EXITS THE EAST COAST, AND RIDGE
AMPLIFICATION OCCURS IN BETWEEN ACROSS THE CENTRAL U.S. A
BLOCKING HIGH-OVER-LOW PATTERN IS DEVELOPING IN THE CANADIAN
MARITIMES SOUTHWARD INTO THE WESTERN ATLANTIC TODAY, BECOMING
QUITE STRONG THIS WEEKEND INTO EARLY NEXT WEEK. MEANWHILE, THE
WESTERN U.S. TROUGH WILL CONTINUE AMPLIFICATION/INTENSIFICATION
THIS WEEKEND, VIA ANTICYCLONIC WAVE BREAKING OVER THE EASTERN
PACIFIC AND THE PROGRESSION OF AN INTENSE SHORTWAVE TROUGH IN
THE NORTHEAST PACIFIC, WHICH WILL ACT AS A KICKER TO THE WESTERN
U.S. SYSTEM. I SAY WESTERN U.S., BUT BY LATE WEEKEND, THE TROUGH
WILL EXTEND WELL INTO MEXICO, ACQUIRING A NEUTRAL AND THEN
NEGATIVE TILT AS IT EJECTS RAPIDLY NORTHEASTWARD INTO THE
CENTRAL PLAINS BY MONDAY.
DOWNSTREAM OF HIGH-AMPLITUDE TROUGHING IN THE WESTERN U.S., WE
WILL BE WARM, MOSTLY DRY, AND PROGRESSIVELY BREEZIER ON
SATURDAY. A FEW GUSTS EXCEEDING 30 MPH SEEM LIKELY (> 70 PERCENT
CHANCE) SATURDAY AFTERNOON, PARTICULARLY WEST OF U.S. HIGHWAY
65. I SAY MOSTLY DRY BECAUSE A FRONT WILL APPROACH NORTHWEST
PORTIONS OF THE CWA DURING THE AFTERNOON. THERE MAY BE
SUFFICIENT LIFT TO GENERATE A SHOWER (OR EVEN A STORM) DURING
THE AFTERNOON/EVENING (MAINLY NORTHWEST OF I-35), THOUGH
COVERAGE SHOULD BE SPARSE AND INTENSITY WOULD BE QUITE LIMITED.
OTHERWISE, ENJOY THE WARM AND (MOSTLY) DRY WEATHER, BECAUSE THE
FORECAST CONDITIONS DETERIORATE QUICKLY THEREAFTER.
MODELS HAVE REALLY STRUGGLED WITH THE TIMING AND TRACK OF THE
EJECTING SYSTEM, AND TO SOME DEGREE, CONTINUE TO DO SO. WITH SO
MANY LARGE-SCALE UPPER-AIR PLAYERS, THIS IS UNSURPRISING,
PARTICULARLY GIVEN TWO CAUSAL PHENOMENA WITH RELATIVELY LIMITED
UNDERSTANDING SCIENTIFICALLY (WAVE BREAKING AND HIGH-AMPLITUDE
BLOCKING). NEVERTHELESS, THERE ARE SOME ASPECTS OF THE SYSTEM'S
PROGRESSION THIS WEEKEND INTO NEXT WEEK THAT HAVE SHOWN GOOD
CONSISTENCY. ONE SUCH ASPECT IS DEVELOPMENT AND GEOGRAPHIC
PLACEMENT OF PRECIPITATION AND RESULTANT OVERALL QPF, WITH
ENSEMBLES HAVING SHOWN >50 PERCENT PROBABILITIES OF 1+ INCH
RAINFALL TOTALS SUNDAY NIGHT THROUGH MONDAY NIGHT FOR SEVERAL
DAYS NOW. PROBABILITIES ARE NOW EXCEEDING 70 PERCENT WEST OF
U.S. 65 (IN CLOSER PROXIMITY TO THE CONSENSUS TRACK OF THE
SURFACE LOW, WITH A MOSTLY MERIDIONAL TRACK FROM THE SOUTHERN
GREAT PLAINS TO THE UPPER MIDWEST). THIS RAIN SHOULD MOSTLY BE
BENEFICIAL, GIVEN OUR DRY SEPTEMBER AND OCTOBER. HOWEVER, WITH
NEAR-RECORD PWS AND THE INJECT OF SOME INSTABILITY OVER THE
AREA ON MONDAY, LOCALLY HEAVY RAINFALL IS AN INCREASING CONCERN
(THOUGH FAR FROM A LOCK). CONSIDER A SIMPLE EXAMPLE FROM THE
NBM: THE MEAN TOTAL RAINFALL ACCUMULATION IN THE CURRENT
FORECAST FOR KMCI IS AROUND 1.5 INCHES THROUGH TUESDAY MORNING.
HOWEVER, THE 90TH PERCENTILE IS AROUND 2.35 INCHES, AND THE
MAXIMUM IS CLOSE TO 4 INCHES. IN OTHER WORDS, THE CEILING OF
PRECIPITATION TOTALS FOR THIS SYSTEM IS HIGH. IF A COMBINATION
OF FACTORS PLAYED OUT (CLOSER TRACK OF THE SURFACE LOW TO OUR
AREA, SLIGHTLY SLOWER PROGRESSION, AND FAVORABLE TIMING OF THE
COLD FRONT WITH THE DIURNAL MAXIMUM IN HEATING ON MONDAY...NOT
TO MENTION THE ADDITION OF CONVECTIVE ENHANCEMENT TO
PRECIPITATION RATES ON MONDAY), AN INSTANCE OR TWO OF
FLOODING/FLASH FLOODING IS PLAUSIBLE.
REGARDING THE AFOREMENTIONED INSTABILITY ON MONDAY, THIS IS
PERHAPS THE BIGGEST CHANGE IN THE FORECAST IN THE PAST 24 HOURS.
MODEL SOUNDINGS CLEARLY EXHIBIT THIN/MARGINAL CAPE PROFILES
MONDAY AFTERNOON AS INTENSE WARM/MOIST ADVECTION IN THE LOW
LEVELS COMBINES WITH STRONG DCVA/LIFT IN THE MID LEVELS TO
PERMIT BUOYANCY. ADDITIONALLY, SUCH BUOYANCY MAY BE BOUNDARY-
LAYER BASED, GIVEN EXAMINATION OF BUFKIT SOUNDINGS. IT IS NOT
ENTIRELY SURPRISING THAT THE CSU MACHINE LEARNING CONVECTIVE
OUTLOOKS FEATURE LOW-END PROBABILITIES (LESS THAN 15 PERCENT) OF
SEVERE WEATHER ON MONDAY IN PORTIONS OF KANSAS AND MISSOURI,
GIVEN THE LOOK OF THESE MODEL SOUNDINGS COMBINED WITH VERY HIGH
TO EXTREME DEEP-LAYER SHEAR (SURFACE-TO-500 MB MEDIAN VALUES
NEAR 60 KT). THOUGH MAGNITUDE OF MIXED-LAYER INSTABILITY WILL
OBVIOUSLY BE A LIMITING FACTOR, IT IS NOT OUT OF THE QUESTION A
STRONG TO SEVERE STORM IS PRESENT MONDAY AFTERNOON IN OR CLOSE
TO OUR FORECAST AREA (ESPECIALLY GIVEN THE STRONG WINDS JUST
ABOVE THE SURFACE; SEE BELOW). FORECAST-WISE, HAVE INCLUDED
THUNDER MENTION THROUGHOUT THE AREA ON MONDAY. WILL NEED TO KEEP
AN EYE ON SEVERE POTENTIAL THROUGH THE WEEKEND.
A HIGHER-CONFIDENCE ASPECT OF THE SYSTEM WILL BE WINDS. AS THE
SURFACE LOW LIFTS NORTHWARD ON MONDAY, THE STRONG PRESSURE
GRADIENT IMMEDIATELY TO ITS EAST WILL BE POSITIONED ACROSS THE
REGION FOR MUCH OF THE DAY. VERY STRONG WINDS (40+ KT) JUST
ABOVE THE SURFACE LEAVE THE POTENTIAL FOR MIXING TO KICK UP
WIND GUSTS EXCEEDING 40-45 MPH AT TIMES. THE CHALLENGE WILL BE
THE EFFICIENCY OF THE MIXING, WITH EXTENSIVE CLOUDINESS AND
PRECIPITATION PRESENT. HOWEVER, EVEN WITH MODEST HEATING AND/OR
A STRONGER DOWNDRAFT ATTENDANT TO A CONVECTIVE STORM, STRONG
WIND GUSTS COULD REACH THE SURFACE READILY. WOULD NOT BE
SURPRISED IF THE NEED FOR A WIND ADVISORY ON MONDAY BECOMES
APPARENT.
THE SYSTEM'S DRY SLOT SWEEPS INTO AND THROUGH THE AREA MONDAY
NIGHT AND TUESDAY, AS CYCLOLYSIS OCCURS WITH THE DEPARTING
SYSTEM IN THE UPPER MIDWEST. THE COLD AIR WILL LAG THE DRY SLOT
BY A CONSIDERABLE AMOUNT OF TIME, LEADING TO ONE MORE MILD,
THOUGH FAIRLY BREEZY, DAY ON TUESDAY. THEREAFTER, THE
AFOREMENTIONED KICKER SYSTEM RAPIDLY AMPLIFIES IN THE ROCKIES
AND RACES EAST THROUGH THE REGION ON WEDNESDAY. MUCH COLDER AIR
WILL THEN PROGRESS SOUTHEASTWARD THROUGH THE CENTRAL U.S.,
LEADING TO HIGHS IN THE LOW TO MID 40S AND LOWS IN THE 20S FOR
MUCH OF THE REST OF THE WEEK. ASIDE FROM THE COLDER
TEMPERATURES, ANOTHER ROUND OF STRONG NORTHWEST WINDS MAY OCCUR
ON WEDNESDAY IN THE WAKE OF THE REINFORCING SYSTEM (UP TO A 40
PERCENT CHANCE FOR WIND GUSTS > 45 MPH).
ONE QUESTION MARK IS IF THE DEVELOPING SYSTEM ON WEDNESDAY
BRINGS US ANY PRECIPITATION BEFORE ITS QUICK DEPARTURE STAGE
EAST. CURRENTLY, I AM SKEPTICAL. THE BIG MODEL TREND TODAY IS
FOR THE DOWNSTREAM ATLANTIC BLOCKING TO BREAK DOWN AND/OR SHIFT
EASTWARD SUFFICIENTLY FOR THE SYSTEM TO DEVELOP/INTENSIFY WELL
EAST OF OUR AREA. THIS HAS THE MAKINGS FOR A COLD BUT DRY SPELL
FOR THE MISSOURI VALLEY. IT ALSO WOULD SUGGEST THAT TEMPERATURE
RECOVERY COULD BE FASTER THAN PREVIOUS MODEL RUNS HAVE
SUGGESTED (I.E., TEMPERATURES WARMING TO NEAR SEASONAL AVERAGES
AS EARLY AS THE END OF THE WEEK). HAVING SAID THIS, MODEL
VOLATILITY IS QUITE HIGH NEXT WEEK, PARTICULARLY REGARDING THE
BLOCKING PATTERN IN THE ATLANTIC, SO RATHER LARGE CHANGES TO THE
FORECAST IN THE EXTENDED PERIOD MAY CONTINUE FOR THE NEXT FEW
DAYS.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1142 AM CST FRI NOV 15 2024
VFR CONDITIONS ARE EXPECTED (>90 PERCENT CHANCE) AT THE TAF
SITES THE NEXT 24 HOURS. SOUTH TO SOUTHEAST WINDS UP TO OR
AROUND 10 KT THROUGH TONIGHT SHOULD INCREASE TO 10 TO 15 KT WITH
GUSTS 20+ KT BY 15Z SATURDAY. EVEN STRONGER WINDS/GUSTS ARE
ANTICIPATED SATURDAY AFTERNOON.
EAX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
KS...NONE.
DISCUSSION...CMS
AVIATION...CMS
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