399
FXUS63 KARX 181203
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
603 AM CST MON NOV 18 2024
KEY MESSAGES
- RAIN TO OVERSPREAD THE AREA TODAY WITH 1-1.5 INCHES OF RAIN
COMMON BY TUESDAY MORNING. WORSE CASE SCENARIOS STILL AROUND 2
TO 2.5 INCHES. WIND GUSTS MOSTLY IN THE 30 TO 40 MPH RANGE,
BUT POCKETS OF 45MPH+ MAY ALSO OCCUR DUE TO THE SHOWERS AND
STORMS.
- TURNING COOLER WEDNESDAY INTO THE WEEKEND. RAIN/SNOW CHANCES
WEDNESDAY INTO WEDNESDAY NIGHT (50-70% FOR 0.1" OR MORE)
ACCOMPANIED BY BREEZY TO WINDY WEST WINDS. THE COMBINATION OF
SNOW SHOWERS AND WINDS MAY REDUCE VISIBILITIES.
DISCUSSION
ISSUED AT 415 AM CST MON NOV 18 2024
OVERVIEW:
INCREASING HIGH CLOUDS WITH SOME PATCHY FOG WAS NOTED ON THE
GOES NIGHTTIME MICROPHYSICS SATELLITE IMAGERY EARLY THIS
MORNING. AN EXPANSIVE AREA OF CLOUDS WERE NOT FAR AWAY WITH MVFR
CEILINGS TO THE SOUTH AT DBQ AND THE AREA OF RAINFALL EXPANDING
NORTHWARD ACROSS MISSOURI. TEMPERATURES AT 10Z WERE IN THE
UPPER 20S TO MID 30S WITH LIGHT SOUTH WINDS. DENSE FOG WAS
DEVELOPING OVER PARTS NORTHERN ILLINOIS AND SOUTHERN WISCONSIN
WITH THE STALLED FRONT LOCATED NEAR CHICAGO TOWARD PEORIA.
WATER VAPOR SATELLITE IMAGERY, HEIGHTS, AND LIGHTNING SHOWED A
CLOSED LOW OVER ONTARIO WITH THE SOUTHERN CLOSED LOW OVER SOUTHERN
NEW MEXICO. A COUPLE OF LINES OF STORMS WERE NOTED WITH THE AREAS OF
RAIN ACROSS THE SOUTHERN PLAINS FROM ARKANSAS INTO TEXAS. ALSO OF
NOTE WAS THE TROPICAL CONNECTION OF MOISTURE FROM 10 TO 20 DEGREES
NORTH LATITUDE STREAMING NORTHWARD AHEAD OF THE CLOSED LOW.
RAIN TO OVERSPREAD THE AREA TODAY WITH 1-1.5 INCHES OF RAIN
COMMON BY TUESDAY MORNING. WIND GUSTS MOSTLY IN THE 30 TO 40
MPH RANGE, BUT POCKETS OF 45MPH+ MAY ALSO OCCUR DUE TO THE
SHOWERS AND STORMS:
THROUGH TUESDAY, THE CLOSED LOW OVER SOUTHERN NEW MEXICO WILL LIFT
NORTHEAST THROUGH THE PLAINS, DEEPENING, BECOMING NEGATIVELY TILTED
OVER THE MISSOURI RIVER VALLEY AND UPPER MISSISSIPPI VALLEY, MERGING
WITH THE TROUGH OVER THE PACIFIC NORTHWEST. STRONG 850 MB MOISTURE
TRANSPORT VECTORS OVER TEXAS TOWARD MISSOURI CONTINUES TO EXPAND
ACROSS MISSOURI AND IOWA TODAY INTO SOUTHERN MINNESOTA THROUGH
00Z; SHIFTING EASTWARD ACROSS ILLINOIS, WISCONSIN, AND INDIANA
TONIGHT. THE 18.00Z DVN RADIOSONDE HAD 1.03" OF PRECIPITABLE
WATER (PWAT). THROUGH TODAY, THE PWAT VALUES CLIMB TO 1 TO
1.40". THE STEADIER RAIN IS FORECAST TO INCREASE FROM SOUTH TO
NORTH AFTER AROUND 10 OR 11AM AND CONTINUING THROUGH MIDNIGHT,
THEN DECREASING FROM SOUTH TO NORTH THROUGH TUESDAY
MORNING...BUT LINGERING NORTH OF I94 THROUGH TUESDAY. FROM THE
18.00Z NAEFS, THIS IS 3 TO 4 STANDARD DEVIATIONS ABOVE NORMAL.
THE EFI CONTINUE TO SHOW ANOMALOUS PRECIPITATION WHEN COMPARED
TO THE CLIMATOLOGY WITH 70 TO 90% OF THE ENSEMBLE MEMBERS AND
THE SHIFT OF TAILS AROUND 1 TOWARD EAU. THE HREF ENSEMBLES
CONTINUE TO SHOW HIGH PROBABILITIES (60-80%) FOR 1" OR RAINFALL
FOR THE FORECAST AREA. THERE ARE SOME POCKETS OF LOWER
PROBABILITIES THOUGH. THE HREF PROBABILITIES FOR 1.5" ARE MOSTLY
0 TO 30% WITH SOME HIGHER 30-60% PROBABILITIES OVER PARTS OF
NORTHEAST IOWA AND SOUTHWEST WISCONSIN. THIS LOOKS TO BE
REFLECTIVE OF WHERE WE HAVE ADDED SOME THUNDER PROBABILITIES.
THE HREF MEANS ARE .5" TO 1.25" WITH LESS FARTHER NORTH OVER
NORTH CENTRAL WI AND HIGHER AMOUNTS FOR PARTS OF NORTHEAST IOWA
AND SOUTHWEST WI. THE HREF LPMM SHOWS SOME POTENTIAL FOR HIGHER
END MAX AMOUNTS UP TO 2 OR 2.5". THERE ARE A COUPLE OF PERIODS
OF INSTABILITY; DURING THE LATE AFTERNOON, DURING THE EVENING
WITH MUCAPE OF 50 TO POSSIBLY 400J/KG ACROSS OUR SOUTHERN
FORECAST AREA TOWARD DBQ, THEN OVERNIGHT WITH 50 TO 80J/KG
LIFTING ACROSS THE FORECAST AREA. THE POTENTIAL FOR STORMS ARE
WITH THE MOISTURE TRANSPORT, FRONTOGENESIS AND STRONGER WINDS
MOVING IN. 0-6KM SHEAR IS FORECAST TO BE AROUND 60 TO 70KTS. AT
THIS TIME, DUE TO THE LIMITED INSTABILITY, LOCALIZED LIGHTNING
AND GUSTY WINDS WITH THE SHOWERS AND STORMS MIXING DOWN SOME OF
THE STRONGER WINDS APPEAR TO BE THE PRIMARY HAZARDS.
WE CURRENTLY HAVE WIND GUSTS OF 30 TO 45 MPH IN THE FORECAST
REALIZING STRONGER GUSTS ARE POSSIBLE DUE TO THE SHOWERS AND A FEW
STORMS. THE 18.00Z HREF GUIDANCE IS QUITE AGGRESSIVE WITH HIGH 80 TO
100% PROBABILITIES OF 40MPH+ WINDS AREAWIDE. A DEEPER DIVE SHOWS
SOME OF THE ARW AND NSSL MEMBERS HAVE 45 TO 60 MPH GUSTS, HOWEVER
THE HRRR/RAP ARE MOSTLY 25 TO 35KTS WITH SOME 35 TO 40KTS GUSTS FOR
TAYLOR AND CLARK CO. THRU 02Z, THEN THE HRRR HAS GREATER COVERAGE OF
THE 40KTS WINDS WITH THE RAP WITH GREATER 30 TO 35KTS WITH POCKETS
OF 40KTS. FORECAST SOUNDINGS SHOW THE 40-60KT WINDS ARE AT THE
1500-2000FT LEVEL AND ABOVE, SO THE MODELS LOOK LIKE THEY ARE
MIXING DOWN THESE STRONGER WINDS TO VARYING DEGREES. AT THIS
TIME, THERE IS NOT ENOUGH CERTAINTY IN THE COVERAGE OF THE
STRONGER WIND GUSTS TO GO WITH A WIND ADVISORY.
TURNING COOLER WEDNESDAY INTO THE WEEKEND. RAIN/SNOW CHANCES
WEDNESDAY INTO WEDNESDAY NIGHT (50-70% FOR 0.1" OR MORE
ACCUMULATION) ACCOMPANIED BY BREEZY TO WINDY WEST WINDS:
COOLER AIR WRAPS INTO THE STORM SYSTEM TUESDAY WITH THE SOUTH WINDS
SHIFTING TO THE WEST. AS THE MERGED STORM SYSTEM HAS AN AREA OF
FRONTOGENESIS MOVE THROUGH TUESDAY NIGHT. THERE IS ENOUGH COLD
AIR THAT PRECIPITATION WOULD BE IN THE FORM OF LIGHT SNOW. AT
THIS TIME IT IS LOOKING DRY TUESDAY NIGHT, HOLDING OFF UNTIL
WEDNESDAY AND WEDNESDAY NIGHT WHEN THE CLOSED LOW MOVES OVER THE
REGION. LIGHT SNOW ACCUMULATIONS WILL BE POSSIBLE ON GRASSY
AREAS AND HIGHER ELEVATIONS. BRISK WINDS WITH GUSTS 20 TO 35MPH
ARE POSSIBLE DURING THIS TIME AS WELL. 18.00Z ECE/GEFS/CANADIAN
ENSEMBLES HAVE A 50 TO 70% CHANCE OF MEASURABLE SNOW (0.1" OR
MORE) OF SNOW AND 10-30% PROBABILITY OF 1" OR MORE, BUT HIGHER
ELEVATIONS COULD SEE MORE. LOOKING AT THE NAM SNOW SQUALL
PARAMETER FOR WEDNESDAY THE VALUE DOES RANGE FROM 1 TO 5 ACROSS
PARTS OF SOUTHEAST MINNESOTA AND NORTHEAST IOWA FROM 18-03Z.
CONDITIONS DO SHOW SOME INSTABILITY, STEEP LAPSE RATES, AND SNOW
SHOWERS ACCOMPANIED BY GUSTY WESTERLY WINDS. IT IS STILL A FEW
DAYS OUT, BUT WILL MENTION THE POTENTIAL FOR REDUCED
VISIBILITIES IN THE HWO.
HIGHS TODAY AND TUESDAY IN THE 50S, BUT MUCH COOLER
TEMPERATURES WEDNESDAY INTO THE WEEKEND WITH HIGHS IN THE 30S
AND 40S.
AVIATION /12Z TAFS THROUGH 12Z TUESDAY/
ISSUED AT 534 AM CST MON NOV 18 2024
INITIAL FORECAST DIFFICULTIES ARE DECREASED VISIBILITIES FROM
AN AREA OF VALLEY FOG THAT HAS SHIFTED NORTH THROUGH THE
OVERNIGHT HOURS. CURRENTLY AFFECTING KLSE TAF SITE WITH 1/4 SM
TO 1 1/2 SM OBSERVED OVER THE LAST COUPLE OF HOURS.
PRECIPITATION SPREADS FROM SOUTHWEST TO NORTHEAST LATER THIS
MORNING INITIALLY AFFECTING SMALLER AIRPORTS IN NORTHEAST IOWA
(KOLZ,KCCY), FOLLOWED BY SOUTHEAST MINNESOTA (KRST, KONA, KFKA)
INTO WESTERN WISCONSIN (KLSE, KPDC, KOVS), AND EVENTUALLY
MOVING INTO CENTRAL WISCONSIN (KBCK, KMDZ) EARLY THIS EVENING.
EXPECT ACCOMPANYING FLIGHT RESTRICTIONS SHORTLY THEREAFTER.
DECREASING CEILING RESTRICTIONS EXPECTED TO BE TEMPORALLY
LIMITED WITH ONLY A COUPLE OF HOURS FROM MVFR TO IFR AND THEN
LIFR. WASN'T COMFORTABLE IN LOCKING DOWN LIFR AT THE CURRENT
FORECAST HOUR AND THEREFORE HAVE INCLUDED WITHIN A PROB30 AT
BOTH KLSE AND KRST TAF SITES. NO SITES IN PARTICULAR ARE
EXPECTED TO BE SPARED FROM THE LOWEST FLIGHT RESTRICTIONS. RAIN
EXPECTED TO BE HEAVY AT TIMES AND HAVE ACCOUNTED FOR WITH
VISIBILITY RESTRICTIONS IN TAFS.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...ZAPOTOCNY
AVIATION...JAR
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