179
FXUS61 KILN 171105
AFDILN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
605 AM EST FRI JAN 17 2025
SYNOPSIS
WARMER AIR WILL BRIEFLY BUILD INTO THE REGION TODAY BEFORE RAIN,
WITH PERHAPS A RAIN AND SNOW MIX, OVERSPREADS THE AREA TONIGHT
INTO THE DAY SATURDAY. SOME ADDITIONAL LIGHT SNOW MAY BE
POSSIBLE FOR PARTS OF THE AREA EARLY SUNDAY. A SIGNIFICANT COLD
AIR OUTBREAK IS EXPECTED SUNDAY INTO MIDWEEK BEFORE MORE
SEASONABLE TEMPERATURES RETURN BY THE SECOND HALF OF THE
UPCOMING WORKWEEK.
NEAR TERM /THROUGH TONIGHT/
DRY CONDITIONS HAVE EVOLVED AREA-WIDE UNDERNEATH A BLANKET OF
STRATUS, WHICH CONTINUES TO ERODE/DRIFT SLOWLY ON THE SW/W
FLANK AS LL WAA SLOWLY INCREASES. EXPECT A TRANSITION TO CLEARER
SKIES AROUND/AFTER DAYBREAK, WITH MOSTLY SUNNY CONDITIONS
EXPECTED FOR MOST OF THE DAY. THIS, COMBINED WITH STEADY
SOUTHERLY LL FLOW, WILL HELP TEMPS REACH INTO THE UPPER 30S
NEAR/N OF I-70 TO THE MID/UPPER 40S S OF THE OH RVR. WENT A FEW
DEGREES ABOVE GUIDANCE GIVEN THIS SETUP, ESPECIALLY WITH THE
EXPECTATION FOR ABUNDANT SUNSHINE THROUGH THE HEART OF THE
DAYTIME.
WITH CLEARING EXPECTED FOR THE TRI-STATE BY 10Z-11Z, THERE IS
STILL SOME PATCHY FOG POTENTIAL TOWARD/BEYOND SUNRISE ACROSS
THE TRI- STATE INTO SE IN WHERE SKIES WILL BE CLEAREST, AND
WINDS WILL BE LIGHTEST, BUT SUBTLE WAA OVER A VERY COLD
GROUND/SNOWPACK WILL ALREADY BE UNDERWAY. SOME LATE-NIGHT
CLEARING FOR THE TRI-STATE COULD LEAD TO A SEVERAL HOUR PERIOD
OF PATCHY FOG POTENTIAL IF EVERYTHING COMES TOGETHER JUST RIGHT.
BUT DO THINK THE BEST SETUP FOR MORE WIDESPREAD FOG WILL STAY
OFF TO THE SW OF THE LOCAL AREA, MORE ACROSS SRN IL/IN.
SHORT TERM /SATURDAY/
THE "WARMER" AND QUIETER STRETCH DURING THE NEAR TERM PERIOD
WON'T CONTINUE INTO THE SHORT TERM PERIOD AS A QUICK-MOVING
SYSTEM HELPS SPREAD RA, WITH PERHAPS A RASN MIX, INTO THE AREA
PAST MIDNIGHT THROUGH SATURDAY MORNING. THE MOISTENING OF THE
PROFILE SUGGESTS THAT TEMPS MAY NOT BUDGE MUCH TONIGHT,
GENERALLY PLATEAUING IN THE UPPER 30S FOR MOST LOCALES THROUGH
SATURDAY MORNING. THIS BEING SAID, THERE MAY BE JUST ENOUGH COLD
AIR IN THE BL TO ALLOW FOR A MIX OF RA/SN FOR LOCALES NEAR/N OF
I-70 INTO CENTRAL OH BEFORE/AROUND DAYBREAK SATURDAY BEFORE THE
SYSTEM BEGINS TO PULL OFF TO THE E AND COLDER AIR FILTERS IN
AREA-WIDE BY THE AFTERNOON. THIS MAY ALLOW FOR A BRIEF PERIOD OF
ALL SN NEAR/W OF I-71 ON THE BACKSIDE BY EARLY AFTERNOON, BUT
ACCUMULATIONS ARE EXPECTED TO BE RATHER LIGHT/NEGLIGIBLE.
THE BEST POTENTIAL FOR LIGHT/GRASSY/ELEVATED ACCUMULATIONS OF SN
THROUGH SATURDAY AFTERNOON WILL BE ACROSS EC IN AND WC OH, WHERE
UP TO ONE HALF OF AN INCH WILL BE POSSIBLE. BUT THIS SHOULD BE
PRIMARILY CONFINED TO GRASSY/ELEVATED SURFACES AS SFC AIR/GROUND
TEMPS WILL BE SOMEWHAT UNSUPPORTIVE OF ACCUMULATION, ESPECIALLY
IN LIGHTER RATES. IMPACTS FROM THIS SYSTEM ARE EXPECTED TO BE
RATHER MINIMAL, BUT CERTAINLY SOME ISOLATED SLICK SPOTS CANNOT
BE RULED OUT LATE SATURDAY EVENING AS RESIDUAL MOISTURE ON THE
GROUND WILL LIKELY FREEZE GIVEN THE COLDER AIR SETTLING BACK
INTO THE AREA.
TOTAL LIQUID-EQUIVALENT PRECIP THROUGH THE SHORT TERM PERIOD
WILL BE ON THE ORDER OF ONE QUARTER TO ONE THIRD OF AN INCH,
WHICH, WHEN COMBINED WITH AN EXTENDED (~36 HRS) STRETCH OF ABOVE
FREEZING TEMPS, SHOULD PUT A SIZABLE DENT IN THE
DEEP/COMPACT/CRUSTY SNOWPACK ACROSS MOST OF THE AREA. THERE IS
STILL SOME UNCERTAINTY IN JUST HOW MUCH SNOW WILL STILL BE
LINGERING ABOUT BY SATURDAY NIGHT, WHICH WILL BE IMPORTANT
BECAUSE THIS WILL LIKELY HAVE /SOME/ IMPACT ON JUST HOW HARSH
THE UPCOMING ARCTIC OUTBREAK COULD BE FOR US LOCALLY.
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/
ON SATURDAY EVENING, THE EASTERN HALF OF THE CONUS WILL BE
UNDERNEATH A VERY BROAD MID-LEVEL TROUGH. AT THE SURFACE, A COLD
FRONT WILL BE ON ITS WAY THROUGH THE AREA, REPRESENTING THE LEADING
EDGE OF A VERY COLD AIR MASS THAT WILL ENVELOP THE REGION FOR THE
NEXT SEVERAL DAYS. PRECIPITATION ASSOCIATED WITH THE FRONT WILL BE
COMING TO AN END ON SATURDAY NIGHT, BUT FORCING ALOFT WILL ACTUALLY
BEGIN TO INCREASE HEADING INTO SUNDAY MORNING, AS A SHORTWAVE PIVOTS
AND MOVES EASTWARD OUT OF THE MIDDLE MISSISSIPPI VALLEY REGION INTO
THE OHIO VALLEY. SNOW IS APPEARING A LITTLE MORE LIKELY AHEAD OF
THIS SHORTWAVE ON SUNDAY THAN IN PREVIOUS FORECASTS, SO POPS HAVE
BEEN INCREASED SLIGHTLY, AND SOME LIGHT ACCUMULATIONS (UP TO AN
INCH) ARE NOW IN THE GRIDS. TO NOTE -- THIS WILL PRIMARILY AFFECT
THE SOUTHEASTERN AND EASTERN SECTIONS OF THE ILN FORECAST AREA ON
SUNDAY, WITH OTHER PARTS OF THE AREA ALREADY BEHIND THE PIVOTING
TROUGH BEFORE IT STARTS PRODUCING PRECIPITATION. A WELL-MIXED AND
COLD BOUNDARY LAYER, WITH AT LEAST SOME CONTRIBUTION FROM THE
DENDRITIC GROWTH ZONE, MAY SUPPORT SOME FLURRIES EVEN OUTSIDE OF
AREAS CURRENTLY FORECAST FOR SNOW ON SUNDAY.
THE MONDAY-TUESDAY-WEDNESDAY PERIOD WILL BE ESPECIALLY COLD FOR THE
REGION, WITH ARCTIC HIGH PRESSURE GRADUALLY MOVING EAST ACROSS THIS
THREE-DAY STRETCH. MORNING LOW TEMPERATURES ARE EXPECTED TO FALL
BELOW 0F FOR MOST OF THE ILN FORECAST AREA. ADDING TO THE CONCERN IS
THAT WINDS WILL NOT BECOME COMPLETELY CALM THROUGH THIS PERIOD,
PRODUCING WIND CHILLS THAT WILL BECOME RATHER DANGEROUS, ESPECIALLY
IN THE MORNING HOURS. LOOKING AT ENSEMBLE PROBABILITIES, CHANCES
SEEM FAIRLY HIGH THAT WIND CHILLS WILL DROP BELOW -10F, WITH A
CHANCE THAT SOME AREAS (MAINLY THE NORTHERN SECTIONS OF THE ILN CWA)
MAY GET TO -20F. OF COURSE, THERE ARE OUTLIER MODELS AND ENSEMBLE
MEMBERS EVEN COLDER THAN THAT, WITH THE CANADIAN GENERALLY ON THE
COOLER SIDE AND THE GFS GENERALLY ON THE WARMER SIDE. REGARDLESS OF
THE EXACT VALUE, THE COLD CONDITIONS WILL BE SIGNIFICANT AND
HAZARDOUS. AS OF NOW, IT APPEARS THAT A VERY SLIGHT WARM UP COULD
OCCUR FOR THE SECOND HALF OF THE WEEK, SO THE COLDEST CONDITIONS
WILL LIKELY BE FOCUSED ON THE MORNINGS OF MONDAY, TUESDAY, AND
WEDNESDAY. BY LATER WEDNESDAY, AS THE HIGH MOVES TO THE EAST, FLOW
SHOULD SWITCH TO THE SOUTH -- BRINGING WHAT CAN TECHNICALLY BE
DESCRIBED AS WARM ADVECTION TO AN AIR MASS THAT IS ANYTHING BUT
WARM.
AVIATION /12Z FRIDAY THROUGH TUESDAY/
A BLANKET OF VFR CIGS CONTINUE TO DRIFT TO THE E THROUGH THE
REGION AND, DESPITE SOME REDEVELOPMENT, A CLEARING TREND IS
ADVANCING ACROSS THE AREA EARLY THIS MORNING. SCATTERING/CLEARING
WILL WORK ITS WAY E/NE THROUGH 15Z, ALLOWING FOR MOST SPOTS TO
GO SKC FOR THE MAJORITY OF THE DAYTIME.
THE CLEARING SKIES EARLY THIS MORNING HAVE ALLOWED SOME BRIEF
BR/MVFR VSBYS TO DEVELOP, MAINLY FOR KLUK, FOR AN HOUR OR TWO
BEFORE VFR CONDITIONS RETURN AREA-WIDE.
AFTER BR AT KLUK DISSIPATES, VFR CONDITIONS ARE EXPECTED
THROUGHOUT THE DAY, WITH MAINLY CLEAR SKIES. MID/HIGH CLOUDS
WILL BE ON THE INCREASE PAST 00Z FROM THE SW WITH THE APPROACH
OF THE NEXT SYSTEM, WITH A MOISTENING/SATURATING OF THE PROFILE
EXPECTED FROM SW TO NE NEAR/AFTER 06Z SATURDAY. THE STEADY LIGHT
RA, OR PERHAPS A RASN MIX, PAST 06Z WILL EVENTUALLY LEAD TO IFR
CIGS AND VSBYS FOR MUCH OF THE AREA BY 12Z SATURDAY.
THE OTHER ITEM OF INTEREST IS GOING TO BE SOME SW LLWS ON THE
ORDER OF 40-45KTS PAST 00Z SATURDAY. LIGHT SW FLOW EARLY THIS
MORNING WILL GO MORE SOUTHERLY AND INCREASE TO 10-15KTS, WITH
THE OCCASIONAL GUST TO 15-20KTS. SOUTHERLY FLOW AT 10-12KTS
WILL GO MORE OUT OF THE SW TOWARD 06Z AND BEYOND, SLOWLY
DECREASING TOWARD 12Z SATURDAY.
OUTLOOK...IFR CIGS/VSBYS ARE LIKELY ON SATURDAY. MVFR CIGS AND
VSBYS POSSIBLE SUNDAY.
ILN WATCHES/WARNINGS/ADVISORIES
OH...NONE.
KY...NONE.
IN...NONE.
SYNOPSIS...KC
NEAR TERM...KC
SHORT TERM...KC
LONG TERM...HATZOS
AVIATION...KC
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