415
FXUS63 KOAX 152331
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
631 PM CDT TUE APR 15 2025
KEY MESSAGES
- VERY HIGH FIRE DANGER EXPECTED WEDNESDAY (MOST OF THE AREA)
AND THURSDAY (EASTERN NEBRASKA).
- INCREASING AMOUNTS OF NEAR SURFACE SMOKE TONIGHT THROUGH MID-
MORNING WEDNESDAY DUE TO SEASONAL BURNING ACROSS THE KANSAS
FLINT HILLS.
- SHOWER AND STORMS WEDNESDAY NIGHT INTO THURSDAY (30-50%
CHANCE). A FEW STORMS COULD BE SEVERE WEDNESDAY NIGHT/THURSDAY
MORNING (5-15% CHANCE) WITH DAMAGING WIND THE PRIMARY THREAT.
THE THREAT OF SEVERE STORMS INCREASES THURSDAY
AFTERNOON/EVENING (15-30% CHANCE) WITH HAIL THE PRIMARY
THREAT.
- SHOWER AND STORM CHANCES RETURN TO THE REGION SUNDAY INTO
MONDAY, THOUGH CONFIDENCE IS LOW IN EXACT TIMING/PLACEMENT OF
THE HEAVIEST RAIN.
DISCUSSION
ISSUED AT 348 PM CDT TUE APR 15 2025
IN THE NEAR TERM, SURFACE HIGHT PRESSURE RIDGE EXTENDS NORTHWARD
FROM SOUTHERN KANSAS INTO NORTHEAST NEBRASKA. GUSTY NORTHWEST
WINDS PREVAIL ALONG THE MISSOURI RIVER VALLEY OF NEBRASKA AND
IOWA, WITH WIND GUSTS OCCASIONALLY PEAKING IN THE 25-30 MPH
RANGE. COMBINED WITH THE LOWEST AFTERNOON HUMIDITY FALLING INTO
THE TEENS, THERE ARE POCKETS WHERE NEAR CRITICAL FIRE DANGER
EXISTS, BUT THESE CONDITIONS RALLY TOGETHER ONLY BRIEFLY. AFTER
CONSULTING WITH NEIGHBORING FORECAST AREAS, DECIDED NOT TO HOIST
A RED FLAG WARNING FOR THIS AFTERNOON.
TONIGHT AND WEDNESDAY...
AS THE SURFACE RIDGE AXIS DISSIPATES AS LEE SIDE TROUGH ENHANCES
LOW LEVEL WIND FIELD, WITH DECOUPLING DURING THE OVERNIGHT HOURS
IN CONJUNCTION WITH THE NOCTURNAL INVERSION. A DEVELOPING LOW
LEVEL JET APPROXIMATELY 1500 FT AGL DEVELOPS DURING THE EVENING
AND EARLY MORNING HOURS OF WEDNESDAY. THIS WILL ALLOW SMOKE
FROM SEASONAL BURNING ACROSS THE KANSAS FLINT HILLS TO ADVECT
INTO THE AREA, PROMPTING THE NEBRASKA DEPARTMENT OF HEALTH AND
HUMAN SERVICES AND DEPARTMENT OF ENVIRONMENT AND ENERGY TO ISSUE
AN AIR QUALITY ALERT FROM 9PM THIS EVENING THROUGH 10 AM
WEDNESDAY. AS DIURNAL MIXING INCREASES ON LATE WEDNESDAY
MORNING, THE DENSITY OF LOW LEVEL SMOKE WILL DISSIPATE.
A CURSORY LOOK AT VARIOUS FORECAST SOUNDINGS INDICATING DECENT
MIXING, THUS TRENDED SLIGHT GREATER WITH MAXT (NBM 60%, NBM-75
40%) AND LOWER DEWPOINTS (40% NBM-25 & 60% NBM)AND GREATER WIND
GUSTS (25-30KT).
WEDNESDAY NIGHT INTO FRIDAY...
PRECIPITATION CHANCES INCREASES AFTER MIDNIGHT THURSDAY.
SOUTHERLY LOW LEVEL FLOW ADVECTS INCREASING LOW LEVEL MOISTURE
FROM SURFACE TO 5 KFT AGL, WITH AN ELEVATED MIXED LAYER 10-15
KT. NOCTURNAL DECOUPLING AGAIN IS EXPECTED, THOUGHT LLJ 35-50KT
WILL ADVECT WARM NOSE OF TEMPERATURES. GIVEN THERE WILL NOT BE
ANY PRONOUNCED DYNAMIC FORCING, WITH BULK OF FORECAST AREA ON
THE ANTICYCLONIC SIDE OF THE H3 JET, ISENTROPIC/THERMAL FORCING
WILL BE THE MAIN MECHANISM FOR ANY PRECIPITATION DEVELOPMENT
WITH THE BEST LEFT OCCURRING IN THE CONJUNCTION WITH ELEVATED
MIXED LAYER. THERE IS A RATHER LIMITED INSTABILITY WITH LIFT
FROM THE EML; HOWEVER, ANY SHOWER OR THUNDERSTORM THAT DEVELOPS
AND COLLAPSES THERE IS SUFFICIENT DCAPE TO ACCELERATE THE
DESCENDING PARCELS AND TO PRODUCE DAMAGING WIND GUSTS. THE CAMS
ARE SHOWING DIFFERENCES IN OVERNIGHT DEVELOPMENT, THUS BACKED
OFF NBM POPS.
VARYING SOLUTIONS EXIST IN SURFACE LOW DEVELOPMENT THURSDAY
AFTERNOON, WITH H3 ULJ AXIS EITHER BISECTING OR JUST NORTH OF
THE FORECAST AREA, ALLOWING FOR SYNOPTIC OR MESOSCALE SURFACE
LOW DEVELOPMENT SOMEWHERE NEAR THE KANSAS-NEBRASKA BORDER OR
I-80 CORRIDOR. WHEREEVER THIS LOW DEVELOPS AND NORTHWARD TOWARD
THE JET AXIS LIKELY WILL BE THE BETTER ENVIRONMENT FOR SEVERE
LOCAL LEVEL HELICTY THAT COULD PROMOTE ROTATING UPDRAFT.
MAXIMUM TEMPERATURES POSING A CONUNDRUM. NBM IS TRENDING 5 TO 10
DEGREES WARMER THAN DETERMINISTIC GUIDANCE, CLOSER TO THE 90-95%
PLUME VALUES. TRENDED TOWARD THE LOWER ENVELOPE OF NBM
CONSEQUENTLY OR TEMPERATURES IN THE LOWER 70S ALONG THE SOUTH
DAKOTA BORDER, LOWER-MID 80S ALONG THE I-80 CORRIDOR AND NEAR 90
ALONG THE KANSAS-NEBRASKA BORDER.
PRECIPITATION CHANCES LINGER INTO FRIDAY, AS LARGE SCALE FORCING
INCREASES AS A SERIES OF SMALL SCALE DISTURBANCES TRAVERSE POSITIVELY
TILTED UPPER TROUGH. COMBINATION OF CONVECTION AND UPPER FORCING
DRAGS A COLD FRONT THROUGH THE AREA, WITH LOW LEVEL COLD
ADVECTION DROPPING TEMPERATURES BACK TOWARD SEASONAL HIGH
TEMPERATURES IN THE 60S.
SATURDAY THROUGH TUESDAY...
THERE'S A LULL IN PRECIPITATION CHANCES THE BULK OF THE WEEKEND,
THEN SYNCING OF THE POLAR JET WITH SOUTHERN JET PULL A CLOSED
LOW PER THE DETERMINISTIC MODELS ACROSS THE AREA. EXACTLY HOW
THAT CLOSED H5 LOW TRAVERES IS IN QUESTION, WITH THE ENSEMBLE
MEAN MUTED SIGNALING DIFFERENCES IN THE SOLUTIONS. NONETHELESS,
THERE STILL APPEARS A CHANCE OF PRECIPITATION. TEMPERATURES
APPEAR SEASON WITH HIGHS IN THE 60S AND LOWS IN THE 40S.
AVIATION /00Z TAFS THROUGH 00Z THURSDAY/
ISSUED AT 621 PM CDT TUE APR 15 2025
VFR CONDITIONS EXPECTED DURING THIS TAF CYCLE. BREEZY WINDS WILL
SUBSIDE AS SURFACE MIXING CEASES THIS EVENING. WILL SEE A PERIOD
OF LOW LEVEL WIND SHEAR RETURN AFTER 8Z AND SPREAD EASTWARD AS A
850 MB LOW LEVEL JET DEVELOPS AND SPREADS EASTWARD. WILL SEE
BREEZY SOUTHEASTERLY WINDS RETURN AFTER 13-14Z AHEAD OF AN
APPROACHING LOW PRESSURE SYSTEM.
OAX WATCHES/WARNINGS/ADVISORIES
NE...NONE.
IA...NONE.
DISCUSSION...FORTIN
AVIATION...CASTILLO/NICOLAISEN
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