933
FXUS63 KIWX 201733
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1233 PM EST SAT DEC 20 2025
KEY MESSAGES
- BREEZY TODAY WITH SOUTHERLY WINDS GUSTS AS HIGH AS 30 TO 35
MPH. WINDS SHIFT TO BECOME WEST/NORTHWEST THIS EVENING AND
SLOWLY SUBSIDE THROUGH SUNDAY MORNING.
- NEXT CHANCE FOR RAIN/SNOW ARRIVES MONDAY AFTERNOON INTO TUESDAY.
ADDITIONAL RAIN CHANCES POSSIBLE AROUND CHRISTMAS.
- BRIEFLY COLDER ON SUNDAY WITH HIGHS IN THE UPPER 20S TO LOW
30S BEFORE A WARMING TREND ENSUES NEXT WEEK IN THE LEAD UP TO
CHRISTMAS. HIGH TEMPERATURES ON CHRISTMAS DAY WILL BE NEAR
RECORD LEVELS IN THE UPPER 50S TO LOW 60S!
DISCUSSION
ISSUED AT 243 AM EST SAT DEC 20 2025
A TIGHTENING PRESSURE GRADIENT BETWEEN HIGH PRESSURE CENTERED OVER
THE SOUTHEAST US AND A DEEPENING LOW PRESSURE OVER THE NORTHERN
PLAINS WILL MAKE FOR BREEZY CONDITIONS THROUGH THE EVENING. THE
TRICKIEST PART OF THE FORECAST FOR TODAY IS REGARDING HOW MUCH
THE ATMOSPHERE MIXES OUT AND DESTABILIZES TODAY AHEAD OF AN
INCOMING COLD FRONT (SOUNDINGS SHOW A FAIRLY DEEP AND PERSISTENT
INVERSION NEAR THE SURFACE TODAY). A STRONG LOW LEVEL JET (60+
KT AT 850MB) COULD ALLOW FOR GUSTY SOUTHERLY WINDS TO MIX DOWN
TO THE SURFACE TODAY, ESPECIALLY THIS AFTERNOON AND EVENING. WAA
IS A TOUGHER ENVIRONMENT TO GET SUFFICIENT MIXING DOWN TO THE
SURFACE, SO GIVEN THIS UNCERTAINTY, HAVE STUCK WITH WIND GUSTS
AS HIGH AS 30 TO 35 MPH TODAY. ALTHOUGH, I WOULDN'T BE SURPRISED
IF SPORADIC HIGHER GUSTS ARE REALIZED. THE COLD FRONT COMES
THROUGH THIS EVENING; IT WILL BE A MAINLY DRY FRONT WITH THE
EXCEPTION BEING A FEW ISOLATED SHOWERS POSSIBLE NEAR LAKE
MICHIGAN IN SOUTHWEST LOWER MICHIGAN. ONCE THE FRONT IS THROUGH,
WINDS SHIFT TO BECOME WEST/NORTHWEST AND WILL GRADUALLY SUBSIDE
THROUGH SUNDAY MORNING. ANOTHER COLD NIGHT IS AHEAD AS LOWS
SUNDAY MORNING WILL BE AROUND 20 DEGREES WITH WIND CHILLS IN THE
SINGLE DIGITS TO LOW TEENS.
SUNDAY WILL BE A DRY DAY AS SURFACE HIGH PRESSURE BUILDS IN
OVERHEAD. THE NEXT CHANCES FOR RAIN/SNOW ARRIVE MONDAY AFTERNOON
THROUGH TUESDAY MORNING WITH A QUICK CLIPPER SYSTEM. WITH
TEMPERATURES LIKELY IN THE MID TO UPPER 30S WHEN THIS SYSTEM COMES
THROUGH, WE WILL HAVE TO WATCH THE PRECIPITATION TYPE CLOSELY. THE
GFS IS HINTING AT A POSSIBLE FREEZING DRIZZLE SETUP, HOWEVER, THE
NBM HAS A RAIN/SNOW MIX. A WARM FRONT COMES THROUGH OVERNIGHT MONDAY
INTO EARLY TUESDAY, SO IT IS ALSO POSSIBLE THAT THIS SETUP STARTS AS
FREEZING DRIZZLE AND TRANSITIONS TO JUST A COLD RAIN. DEPENDING ON
PAVEMENT TEMPERATURES, ROADS COULD BE SLICK FOR THE TUESDAY MORNING
COMMUTE.
FOR THOSE HOPING FOR A WHITE CHRISTMAS, UNFORTUNATELY, ALL OF THE
COLD AND SNOW WE EXPERIENCED DURING THE FIRST HALF DECEMBER DOES NOT
APPEAR TO BE RETURNING ANYTIME SOON. THERE IS HIGH CONFIDENCE THAT A
WARMING TREND IS AHEAD TO FINISH OUT THE LAST FULL WEEK OF DECEMBER.
A DOMINANT UPPER LEVEL RIDGE DEVELOPS ACROSS THE CENTRAL PLAINS AND
BRINGS ABOVE AVERAGE WARMTH ACROSS MUCH OF THE CONUS FOR CHRISTMAS.
FOR OUR AREA, NEAR RECORD HIGHS IN THE UPPER 50S TO LOW 60S APPEAR
LIKELY (ESPECIALLY SOUTH OF US 30) FOR CHRISTMAS. WITH ALL OF THIS
WARMTH COMES THE POTENTIAL FOR RAIN AROUND CHRISTMAS AS A LOW
PRESSURE SYSTEM COULD DEVELOP OVER THE GREAT LAKES. CHANCES FOR RAIN
AS OF NOW APPEAR HIGHEST OVERNIGHT CHRISTMAS EVE HEADING INTO EARLY
CHRISTMAS DAY. STAY TUNED!
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1232 PM EST SAT DEC 20 2025
THE MAIN LOW LEVEL JET IS TRANSLATING EASTWARD AWAY FROM THE AREA
THIS AFTERNOON AND THIS WILL ALLOW LLWS TO DISAPPEAR FROM THE
TAFS. ADDITIONALLY, GUSTS WILL DROP BACK BELOW 20 KTS THIS
AFTERNOON AS DIRECTIONS VEER MORE NORTHWESTERLY BY SUNDAY
MORNING.
OTHERWISE, HIGH CLOUDS PROVIDE ONLY A 10-15% CHANCE FOR LIGHT RAIN
LATER THIS AFTERNOON AS A LOW PASSES TO OUR NORTH, BUT GIVEN THE DRY
AIR, AM NOT COMPLETELY CERTAIN THIS HAPPENS. AT THE VERY LEAST,
FLIGHT CONDITIONS ARE EXPECTED TO STAY IN VFR THROUGH THE PERIOD.
ONE OTHER POSSIBILITY IS THAT CONDITIONS DIP DOWN INTO MVFR AS
HAZE/FOG FORMS UNDER THE INVERSION SUNDAY MORNING OR THAT CIGS DIP
INTO MVFR. IT IS INTERESTING TO SEE LAV GUIDANCE KEEP SUSTAINED
WINDS AROUND 10 KTS OR ABOVE, WHICH WOULD POINT TO MORE OF A CIG
ISSUANCE THAN FOG. BUT HAZE COULD STILL BE POSSIBILITY IN THIS
SCENARIO. GIVEN THE LOW CONFIDENCE THAT THESE HAZARDOUS CONDITIONS
HAPPEN, WILL ONLY MENTION THEM HERE AND NOT IN THE TAF
THEMSELVES.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST SUNDAY FOR LMZ043-046.
DISCUSSION...JOHNSON
AVIATION...ROLLER
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