147
FXUS63 KLOT 230231
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
931 PM CDT MON OCT 22 2018
UPDATE
924 PM CDT
AFTER ABOVE NORMAL TEMPERATURES FOR A CHANGE, A COLD FRONT IS
NEARING THE AREA THIS EVENING. NO PRECIP IS COMING WITH THIS
FRONT, BUT THE SHIFT TO NORTHERLY WINDS WILL SIGNAL THE RETURN TO
A BIT COOLER WEATHER FOR A FEW DAYS. WE WILL JUST SEE SOME
SCATTERED STRATOCUMULUS CLOUDS, POSSIBLY SLIGHTLY HIGHER COVERAGE
NEAR THE LAKE.
KMD
SHORT TERM
148 PM CDT
THROUGH TUESDAY...
FOR THE REMAINDER OF THE AFTERNOON AND THROUGH THE NIGHT TONIGHT,
SKIES WILL BE MOSTLY CLEAR WITH ONLY A LITTLE CIRRUS FOR CLOUD
COVER. WINDS SHOULD BE AROUND 10 KT FOR THE EVENING AND
OVERNIGHT, GRADUALLY VEERING FROM WLY TO NWLY AS LOW PRESSURE
MOVES ACROSS THE UPPER GREAT LAKES AND HIGH PRESSURE BUILDS INTO
THE NORTHERN PLAINS. A WEAK SECONDARY COLD FRONT WILL PUSH SOUTH
ACROSS THE LOCAL AREA DURG THE EARLY MORNING HOURS, SHIFTING WINDS
TO NORTHERLY, AND BECOMING MORE BREEZY FOR THE MORNING HOURS
TOMORROW. THIS SECONDARY COLD FRONT OR SURGE OF COOLER AIR WILL
OCCUR EARLY ENOUGH IN THE DAY THAT THERE WILL STILL BE SOME
OPPORTUNITY FOR DIURNAL WARMING AS SKIES REMAIN MOSTLY CLEAR
THROUGH THE DAY. THE MORNING SHOULD START OUT A BIT CHILLY WITH
MORNING LOWS IN THE 30S. WHILE THERE SHOULD BE DEEP LAYER COLD
ADVECTION THROUGH THE DAY UNDER NWLY FLOW ALOFT, HEIGHT RISES
FROM UPPER RIDGING BUILDING OVER THE PLAINS WILL HELP KEEP
CONDITIONS DRY WITH HIGHS IN THE LOW 50S.
LONG TERM
201 PM CDT
TUESDAY NIGHT THROUGH MONDAY...
UPPER TROUGH WILL BE IN THE PROCESS OF MOVING EAST OF THE GREAT
LAKES REGION MIDWEEK. HIGH PRESSURE WILL MOVE EAST OF THE REGION
AS WELL AND ALLOW FOR A BRIEF PERIOD OF RETURN SOUTHERLY FLOW, BUT
NOT LOOKING FOR ANY BIG MODERATION IN TEMPERATURES BEFORE NEXT
SHORTWAVE TROUGH MOVES ACROSS THE REGION FRIDAY WITH SOME SHOWER
POTENTIAL.
HEADING INTO THE WEEKEND, FORECAST CONFIDENCE IN THE OVERALL LARGE
SCALE PATTERN IS INCREASING WITH MEDIUM RANGE MODELS IN GOOD
AGREEMENT ON DEVELOPING A SIGNIFICANT CYCLONE THAT TRACKS NORTH
UP THE EASTERN SEABOARD. CONCURRENTLY, A SERIES OF POTENTIALLY
FAIRLY VIGOROUS CLIPPER-LIKE NORTHWEST FLOW SHORTWAVE TROUGHS ARE
PROGGED TO DIG SOUTHEAST INTO THE GREAT LAKES REGION, EVENTUALLY
PHASING WITH STRONG SOUTHERN STREAM TROUGH RESPONSIBLE FOR THE
EAST COAST CYCLONE. PRECISE DETAILS IN THE INDIVIDUAL CLIPPER
SYSTEM TRACKS AND IMPACTS AS WELL AS THE TRACK/INTENSITY OF THE
EAST COAST STORM COULD CHANGE SOME IN TIME, BUT THE OVERALL LARGE
SCALE PATTERN MODELS SEEMED TO HAVE LOCKED IN TO.
THE RESULT WILL BE A CONTINUATION OF UNSEASONABLY COLD
TEMPERATURES THIS WEEKEND INTO EARLY NEXT WEEK. GOING FORECAST
TEMPS NEAR 50 WILL LIKELY NEED TO BE LOWERED IN LATER FORECASTS IF
MODELS REMAIN CONSISTENT AS CURRENT FORECAST TEMPS ARE BEING
WEIGHTED UP SOMEWHAT BY MOS AND CLIMO. THERE WILL LIKELY BE SOME
PERIODIC BOUTS OF SHOWERS AS THE INDIVIDUAL CLIPPERS MOVE ACROSS
THE AREA AS THEY HELP CARVE OUT THE DEEP LONG WAVE TROUGH OVER
EASTERN NOAM AND GIVEN THE DEPTH OF THE TROUGH AND MAGNITUDE OF
THE INCOMING COLD AIR, SOME MIXED PRECIP OR SNOW SHOWERS CANNOT BE
RULED OUT AS WELL.
- IZZI
AVIATION
FOR THE 00Z TAFS...
THERE ARE AGAIN NO SIGNIFICANT AVIATION IMPACTS EXPECTED FOR THE
NEXT 24 TO 30 HOURS. THE MAIN CONCERN IS WINDS LATER TONIGHT
THROUGH TUESDAY. A COLD FRONT PASSAGE WILL SHIFT WINDS TO
NORTHWEST (300-330) BY 05-07Z TONIGHT. WINDS WILL THEN BECOME
NORTH-NORTHWEST TO NORTH AT TIMES (340-350) BY MID TUESDAY MORNING
THROUGH EARLY TO MID AFTERNOON. HAVE MEDIUM-HIGH CONFIDENCE THAT
PREVAILING DIRECTION WILL PRIMARILY BE WEST OF NORTH. SPEEDS
SHOULD BE IN THE 10-13 KT RANGE. THERE COULD BE SOME GUSTINESS IN
15-20 KT RANGE AT ALL SITES BEHIND THE FRONTAL PASSAGE TONIGHT AND
DURING THE DAY ON TUESDAY. HOWEVER, FORECAST SOUNDINGS ARE A
MIXED BAG AS TO THE MAGNITUDE AND FREQUENCY OF GUST POTENTIAL.
HAVE HIGHEST CONFIDENCE IN PREVAILING GUSTS AT GYY DUE TO
PROXIMITY OF UNSTABLE AIR MASS OVER LAKE MICHIGAN AND NW TO NNW
WIND DIRECTION.
FINALLY, AS GRADIENT RELAXES TUESDAY AFTERNOON WITH HIGH PRESSURE
ESTABLISHING ITSELF OVER THE AREA, EXPECTING WINDS TO FLOP OVER
TO NORTH-NORTHEAST. THERE COULD BE A FEW HOURS OF SPEEDS
NEAR/AROUND 10 KT AT ORD/MDW AFTER WIND SHIFT TO 020-030 BEFORE
SPEEDS DIMINISH TO 5 KT OR LESS TUESDAY EVENING. EXPECTING
CONDITIONS TO REMAIN VFR THROUGH THE PERIOD AT MOST SITES, WITH
VFR CLOUDS AROUND 3500-4000 FT ON TUESDAY THAT MAY GO BKN AT TIMES
FOR CHICAGO AREA TERMINALS. THERE'S A CHANCE THAT GYY COULD HAVE
A PERIOD OF LAKE INDUCED MVFR CIGS AROUND 1500-2500 FT FROM MID
MORNING THROUGH EARLY-MID AFTERNOON.
CASTRO
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ744-LMZ745...1 AM TUESDAY TO 10 PM
TUESDAY.
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