453
FXUS63 KEAX 170920
AFDEAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
320 AM CST SUN NOV 17 2024
KEY MESSAGES
- LOW PROBABILITY SEVERE WEATHER THREAT ON MONDAY.
- WIDESPREAD RAIN WITH 1-2" OF RAIN LIKELY ACROSS THE AREA.
- MUCH COLDER FOR THE LATTER HALF OF THE WEEK WITH SUB-FREEZING
TEMPERATURES LIKELY.
DISCUSSION
ISSUED AT 320 AM CST SUN NOV 17 2024
EARLY MORNING WATER VAPOR IMAGERY SHOWS A LARGE TROUGH SPLITTING
INTO TWO SMALLER UPPER LOWS, ONE MOVING THROUGH THE NORTHERN PLAINS
AND UPPER MIDWEST, AND THE THE OTHER DIGGING INTO THE
SOUTHWESTERN US AND NORTHWESTERN MEXICO. AHEAD OF THE TROUGH, A
STREAM OF HIGH- LEVEL MOISTURE FROM THE PACIFIC IS NOTED,
STREAMING INTO THE CENTRAL AND EASTERN PLAINS. AT THE SURFACE,
A COLD FRONT IS NOTED FROM SOUTHWESTERN IA, SOUTHWEST INTO
SOUTHWESTERN KS. AN AREA OF THUNDERSTORMS HAS DEVELOPED IN
SOUTHWESTERN KS AS THE FRONT MOVED SOUTHWARD IN AN AREA OF
STRONG ISENTROPIC ASCENT, NOTED ON THE 295K TO 300K PRESSURE
PLOTS. THIS AREA OF STORMS POSES A MINOR WRINKLE TO THE
FORECAST FOR TODAY. IT SEEMS UNLIKELY THAT THESE STORMS WILL
SURVIVE THEIR NORTHEASTERN MOVEMENT INTO FAR NORTHEASTERN KS AND
ADJACENT AREAS OF MO. FIRST, THE BEST ASCENT TRENDS MORE
EASTERLY WITH TIME LATER THIS MORNING TO AFTER SUNRISE. SECOND,
INSTABILITY LOOKS VERY WEEK. HOWEVER, IT'S THAT AREA OF ASCENT
THAT MAY LEAD TO ADDITIONAL SHOWERS OVER WEST CENTRAL KS AND
EAST CENTRAL MO LATER THIS MORNING AND INTO THE AFTERNOON HOURS.
GIVEN THAT POTENTIAL, HAVE ADDED SOME SLIGHT CHANCE POPS FOR
OUR WESTERN AND SOUTHERN ZONES.
FOCUS THEN SHIFTS TO TONIGHT INTO MONDAY NIGHT. THE SOUTHWESTERN
TROUGH WILL DEEPEN AND BECOME NEGATIVELY TILTED AS IT MOVES INTO THE
SOUTHERN HIGH PLAINS. THIS TROUGH ORIENTATION WILL DRAMATICALLY RAMP
UP THE LOW AND MID-LEVEL MOISTURE TRANSPORT INTO THE AREA. IN FACT,
THE FORECASTED PRECIPITABLE WATER AHEAD OF THIS SHORTWAVE IS ABOVE
THE NAEFS 1979-2009 CLIMATOLOGY PERIOD AND IS NEARLY 5 STANDARD
DEVIATIONS ABOVE NORMAL. THIS IS A VERY ANOMALOUS AMOUNT OF MOISTURE
SURGING NORTHWARD WITH SIGNIFICANT CONTRIBUTIONS NOTED FROM THE 1000-
850MB, 850MB-700MB, 700-500MB, AND 500-300MB LAYERS. ALL THIS POINTS
TO WIDESPREAD RAINFALL FOR THE AREA FROM EARLY MONDAY MORNING
THROUGH MONDAY NIGHT. GIVEN THE STRONG FORCING/ ASCENT AND VERY
ANOMALOUSLY HIGH MOISTURE, THE AREA WILL LIKELY SEE WIDESPREAD 1-2"
RAIN AMOUNTS. THE LIMITING FACTOR PREVENTING HIGHER RAIN AMOUNTS FOR
THIS EVENT WILL BE THE SPEED THAT RAIN MOVES THROUGH. IN FACT, THE
MID-LEVEL DRY SLOT COULD MOVE OVER THE AREA MONDAY AFTERNOON,
LIMITING THE TIMING FOR HEAVY RAIN TO MAINLY THE MORNING TO EARLY
AFTERNOON.
WITH A DEEP SURFACE LOW, A TIGHT PRESSURE GRADIENT, AND VERY STRONG
WINDS ALOFT, SURFACE WINDS WILL BE VERY STRONG MONDAY AFTERNOON
AND EVENING. OUR CURRENT FORECAST HAS WIND GUSTS IN THE 35-40
MPH RANGE. BUT PROBABILITIES FOR WINDS IN EXCESS OF 45 MPH
CONTINUE TO RANGE FROM 40-70 PERCENT AND IT'S POSSIBLE A WIND
ADVISORY WILL BE NEEDED WITH LATER FORECASTS. FOR WEDNESDAY, IN
THE WAKE OF THE EARLY WEEK SYSTEM, WINDS WILL AGAIN BE QUITE
GUSTY. BUT PROBABILITIES OF WINDS IN EXCESS OF 45 MPH ARE A BIT
LOWER, RANGING FROM 30-60 PERCENT.
ONE OTHER ASPECT TO THIS SYSTEM THAT WILL NEED TO BE CLOSELY
MONITORED IS THE POTENTIAL FOR SEVERE WEATHER. THIS WOULD BE A HIGH-
SHEAR LOW-CAPE EVENT, WITH AN EMPHASIS ON LOW CAPE AT THIS POINT.
ENSEMBLE SPREADS FOR SBCAPE RANGE FROM ROUGHLY 0-550J/KG MONDAY
AFTERNOON. WITH STRONG SHEAR AVAILABLE, THE AMOUNT OF CAPE IS
CRUCIAL AND THAT IS THE BIGGEST UNCERTAINTY RIGHT NOW. GREATER CAPE
WOULD LEAD TO GREATER POTENTIAL FOR SEVERE STORMS. SO AS IT STANDS
NOW, THE POTENTIAL FOR SEVERE WEATHER IS LOW, BUT IS NOT ZERO. IT
WILL JUST DEPEND ON HOW MUCH INSTABILITY CAN DEVELOP DURING THE DAY
MONDAY.
LASTLY, MUCH COLDER AIR WILL MOVE INTO THE REGION FOR THE LATTER
HALF OF NEXT WEEK. TEMPERATURES FROM WEDNESDAY ONWARD, WILL LIKELY
BE 20+ DEGREES COLDER THAN THE PAST SEVERAL DAYS. THAT ACTUALLY
BRINGS US BACK TO NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES FOR THE
AREA.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1046 PM CST SAT NOV 16 2024
CHALLENGING AVIATION FORECAST FOR THE NEXT 24 HOURS, WITH
MULTIPLE CONCERNS TO ADDRESS. FIRST ISSUE IS DEVELOPMENT OF LOW
CLOUDS TONIGHT, WITH A DECK AROUND 4-5 KFT ALREADY DEVELOPING IN
NORTHWEST MISSOURI AND NORTHEAST KANSAS. GUIDANCE CONTINUES TO
VARY SUBSTANTIALLY ON TIMING OF SUB-VFR CIGS (ANYWHERE FROM 06Z
TO 12Z). MVFR CIGS SHOULD GRADUALLY LOWER TO OR BELOW 2000 FEET
AFTER 12Z (>50 PERCENT CHANCE), PERHAPS FOR SEVERAL HOURS. CIGS
MAY GRADUALLY LIFT ABOVE 2000 FEET DURING THE AFTERNOON (AROUND
A 50 PERCENT CHANCE), EVEN TO VFR (ESPECIALLY AT STJ), BEFORE
SLOWLY LOWERING AGAIN AFTER 00Z. MOST PRECIPITATION SHOULD HOLD
OFF UNTIL AFTER 06Z MONDAY; HOWEVER, WOULD NOT BE SURPRISED TO
SEE PERIODS OF DRIZZLE, PRIMARILY AFTER 15Z SUNDAY. THERE IS
APPROXIMATELY A 20 PERCENT CHANCE OF SUB-VFR VSBYS ON SUNDAY,
PARTICULARLY BETWEEN 12Z AND 20Z. WINDS WILL GENERALLY BE LIGHT
AND VARIABLE THROUGH THE PERIOD.
EAX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
KS...NONE.
DISCUSSION...CDB
AVIATION...CMS
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