991
FXUS63 KOAX 181735
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1135 AM CST MON NOV 18 2024
KEY MESSAGES
- WIDESPREAD RAINFALL IS FORECAST (100% POPS) TODAY WITH MANY
LOCATIONS SEEING AMOUNTS OF 1.0-1.5". THERE IS A 5-10% CHANCE
OF A STRONG WIND GUST AND/OR BRIEF TORNADO MAINLY SOUTH OF
I-80 IN NEBRASKA LATE THIS AFTERNOON INTO EVENING.
- TURNING WINDY AND COOLER TUESDAY AND WEDNESDAY WITH BELOW-
NORMAL TEMPERATURES CONTINUING INTO NEXT WEEKEND.
DISCUSSION
ISSUED AT 302 AM CST MON NOV 18 2024
TODAY AND TONIGHT...
A PROMINENT MID/UPPER-LEVEL LOW OVER SOUTHERN NM AND FAR WEST TX
EARLY THIS MORNING IS FORECAST TO UNDERGO DEEPENING WHILE
ACCELERATING NORTH-NORTHEAST WITH THE CIRCULATION REACHING THE
KS-NE BORDER BY THIS EVENING. THE SYSTEM WILL SUBSEQUENTLY
WEAKEN INTO AN OPEN WAVE ACROSS MN BY TUESDAY MORNING. AT THE
SURFACE, AN AREA OF LOW PRESSURE CURRENTLY OVER WESTERN TX WILL
LIKEWISE DEEPEN WHILE PROGRESSING THROUGH KS TODAY BEFORE
TRAVERSING EASTERN NE THIS EVENING. MEANWHILE, AN ASSOCIATED
FRONT PRESENTLY LOCATED ACROSS SOUTHERN KS INTO CENTRAL MO
WILL DEVELOP NORTH AHEAD OF THE LOW INTO THE MID MO VALLEY
THIS AFTERNOON WITH SURFACE DEWPOINTS INCREASING INTO THE 50S
AND PERHAPS LOW 60S SOUTH OF THAT BOUNDARY.
STRONG MOISTURE AND HEAT FLUXES OCCURRING ALONG AND TO THE NORTH
OF A 50-60 MPH LOW-LEVEL JET (LLJ) HAVE CONTRIBUTED TO SCATTERED
SHOWER ACTIVITY AS FAR NORTH AS I-70 IN KS AS OF 2 AM. AND,
THOSE SAME PROCESSES WILL PROMOTE THE CONTINUED NORTHWARD
EXPANSION AND AREAL INCREASE OF THE SHOWERS INTO PORTIONS OF
SOUTHEAST NE AND SOUTHWEST IA BY DAYBREAK, AND MUCH OF THE AREA
BY NOON. SHOWER AREAL COVERAGE WILL BEGIN TO DECREASE FROM
SOUTH TO NORTH THIS AFTERNOON AS THE MID-LEVEL DRY SLOT BEGINS
TO WORK ITS WAY INTO THE REGION. AT THAT TIME, STEEPENING LAPSE
RATES ALOFT COUPLED WITH THE INCREASING MOISTURE SOUTH OF THE
WARM FRONT WILL YIELD A WEAKLY UNSTABLE ENVIRONMENT FOR SURFACE-
BASED PARCELS WITH MODEL SOUNDINGS INDICATING A NARROW AXIS OF
MLCAPE APPROACHING 250 J/KG IMMEDIATELY AHEAD OF THE SURFACE LOW
LATE THIS AFTERNOON INTO EVENING.
LATEST CAM DATA INDICATE A CLUSTER OF LOW-TOPPED THUNDERSTORMS
MOVING INTO SOUTHEAST NE FROM NORTH-CENTRAL AND NORTHEAST KS BY
4 TO 5 PM WITH THAT ACTIVITY SPREADING NORTHEAST THROUGH FAR
EASTERN NE AND PERHAPS EXTREME WESTERN IA THROUGH ABOUT 9 PM.
DESPITE THE MODEST INSTABILITY, SUFFICIENTLY STRONG VERTICAL
SHEAR COULD SUPPORT SOME STORM ORGANIZATION/ROTATION WITH A LOW
CHANCE (5-10%) OF A STRONG WIND GUST AND/OR BRIEF TORNADO,
MAINLY SOUTH OF I-80.
IN REGARD TO RAINFALL AMOUNTS, THIS FORECAST UPDATE WILL
MAINTAIN THE SAME RANGE (25TH-75TH PERCENTILE) OF 1.0-1.5" AT
MOST LOCATIONS WITH LOCALIZED AMOUNTS OF 2"+ POSSIBLE, BASED
OFF WPC SUPER ENSEMBLE 90TH-95TH PERCENTILE RANKS.
THE RAIN WILL END FROM SOUTH TO NORTH TONIGHT WITH WINDS
STRENGTHENING TO 15 TO 25 MPH WITH HIGHER GUSTS BEHIND A COLD
FRONT MOVING THROUGH THE AREA.
HIGHS TODAY WILL RANGE FROM THE UPPER 40S OVER NORTHEAST NE TO
LOWER 60S IN PARTS OF SOUTHEAST NE AND SOUTHWEST IA.
TUESDAY AND WEDNESDAY...
THE 00Z GLOBAL MODELS REMAIN CONSISTENT IN SUGGESTING THAT THE
SYNOPTIC SYSTEM MENTIONED ABOVE WILL BE ABSORBED INTO A
DEEPENING MID/UPPER-LEVEL LOW OVER THE NORTH-CENTRAL U.S. AND
SOUTH-CENTRAL CANADA DURING THIS TIME PERIOD. STRONG HEIGHT AND
PRESSURE GRADIENTS ON THE BACKSIDE OF THAT SYSTEM WILL YIELD
BREEZY TO WINDY CONDITIONS (FROM THE NORTHWEST), ESPECIALLY ON
TUESDAY MORNING ACROSS NORTHEAST NE, AND WEDNESDAY OVER THE
ENTIRE FORECAST AREA. THE FORECAST WILL INDICATE PEAK GUSTS OF
35-45 MPH NEAR THE SD BORDER TUESDAY MORNING WITH GUSTS OF
40-50 MPH OVER NORTHEAST NE AND 35-40 MPH ELSEWHERE ON WEDNESDAY.
A PROLONGED PERIOD OF LOW-LEVEL COLD ADVECTION WILL RESULT IN
COOLING TEMPERATURES. HIGHS WILL RANGE FROM THE UPPER 40S TO
LOWER 50S ON TUESDAY, AND MAINLY 40S ON WEDNESDAY.
THURSDAY THROUGH SUNDAY...
THE DEEP-LAYER LOW LOCATED OVER THE UPPER MIDWEST INTO GREAT
LAKES AND LOWER OH VALLEY AROUND MID WEEK IS FORECAST SHIFT INTO
THE MID ATLANTIC BY THURSDAY. AT THE SAME TIME, MID-LEVEL
RIDGING OVER THE ROCKIES WILL SPREAD EAST INTO THE GREAT PLAINS
AND PERSIST THROUGH THE WEEKEND. IN THE LOW LEVELS, A SURFACE
RIDGE IS EXPECTED TO BUILD INTO THE MID MO VALLEY ON THURSDAY
AND LINGER THROUGH FRIDAY NIGHT. THAT FEATURE WILL WEAKEN BY
THIS WEEKEND AS A LEE TROUGH DEEPENS OVER THE HIGH PLAINS. THAT
LARGE-SCALE PATTERN EVOLUTION WILL YIELD DRY CONDITIONS WILL
BELOW-NORMAL TEMPERATURES (I.E., HIGHS IN THE UPPER 30S TO MID
40S) INTO SATURDAY. WE COULD SEE WARMER CONDITIONS BY SUNDAY
WHEN WINDS SWITCH TO SOUTH.
AS AN INTERESTING SIDE NOTE, THE TEMPERATURE AT OMAHA EPPLEY HAS
YET TO REACH 28 DEGREES THIS FALL, WHICH IS CONSIDERED A HARD
FREEZE. FORECAST LOWS OF 27, 26, AND 25 ARE FORECAST THURSDAY,
FRIDAY, AND SATURDAY MORNINGS, RESPECTIVELY. SO, IT LOOKS LIKE
WE WILL FINALLY SEE THAT HARD FREEZE IN THE AIRPORT VICINITY.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1135 AM CST MON NOV 18 2024
RAIN AND LOW STRATUS ASSOCIATED WITH THE NORTHERN RAIN-SHIELD OF
THE LOW PRESSURE SYSTEM ARE MOVING ACROSS OUR AREA THIS MORNING
REDUCING VISIBILITY AND CREATING IFR/LIFR CONDITIONS AT OUR
TERMINALS. WE MAY SEE SOME IMPROVEMENT THIS AFTERNOON AROUND 21Z
IF THE DRY SLOT GETS FAR ENOUGH NORTH TO BREAK UP THE LOW CLOUDS
OVER KLNK AND KOMA, BUT THAT'S PROBABLY ONLY A 30% CHANCE AT
KOMA AND 50% CHANCE AT KLNK. MORE LIKELY, WE SEE LOW CLOUDS HANG
AROUND UNTIL THE LOW PRESSURE SYSTEM STARTS TO CLEAR THE AREA
AROUND 06-09Z TONIGHT.
WINDS WILL BE SHIFTING TO NORTHWESTERLY AS THIS SYSTEM MOVES OFF
TO THE NORTHEAST THIS EVENING. THEY WILL REMAIN FAIRLY STRONG,
GUSTING TO 30 KT OVERNIGHT. IF WE DO SEE WIND GUSTS DROP DOWN,
WE MAY NEED TO ADD IN LLWS AS WINDS AROUND 1800-2000 FT AGL
WILL STILL BE UP AROUND 45 TO 50 KT. FOR NOW LEAVING IT OUT BUT
MAY BE ADDED LATER.
OAX WATCHES/WARNINGS/ADVISORIES
NE...NONE.
IA...NONE.
DISCUSSION...MEAD
AVIATION...MCCOY
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