955
FXUS63 KIWX 140816
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
416 AM EDT MON OCT 14 2019
SYNOPSIS
ISSUED AT 405 AM EDT MON OCT 14 2019
THE COOL WEATHER PATTERN WILL CONTINUE TODAY AS A RIDGE OF HIGH
PRESSURE BUILDS IN FROM THE WEST. HIGH TEMPERATURES THIS AFTERNOON
ARE EXPECTED TO BE IN THE 50S ACROSS THE AREA UNDER MOSTLY SUNNY
SKIES. SOME PATCHY FROST IS POSSIBLE TONIGHT INTO EARLY TUESDAY
ACROSS PORTIONS OF FAR NORTHEAST INDIANA, SOUTHERN LOWER MICHIGAN,
AND NORTHWEST OHIO. ANOTHER SYSTEM WILL BRING A CHANCE OF SHOWERS
ON TUESDAY, WITH THE BEST CHANCE OF SHOWERS FOR TUESDAY EVENING.
HIGH TEMPERATURES WILL MODERATE INTO THE MID AND UPPER 60S
TUESDAY, BUT WILL COOL BACK DOWN TO AROUND 50 ON WEDNESDAY AS THIS
SYSTEM PASSES OFF TO THE EAST. WINDY CONDITIONS WILL ALSO DEVELOP
TUESDAY NIGHT INTO WEDNESDAY AS THIS COLDER AIR MOVES BACK INTO
THE REGION.
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 405 AM EDT MON OCT 14 2019
MAIN CONCERN FOR THE SHORT TERM WILL BE PATCHY FROST POTENTIAL THIS
MORNING, AND THEN AGAIN FOR TONIGHT/EARLY TUESDAY MORNING.
HIGHLY SHEARED UPPER LEVEL VORT MAX PROGRESSING THROUGH SOUTHERN
PORTION OF DEPARTING ONTARIO UPPER LEVEL LOW HAS ENHANCED LOW
LEVEL FRONTOGENESIS FORCING LAST EVENING INTO EARLY THIS MORNING.
THIS FORCING WILL DIMINISH THIS MORNING AS THE SHEARED VORT MAX
CONTINUES TO DEPART EASTWARD ACROSS THE EASTERN GREAT LAKES.
CLOUDS SHOULD DIMINISH ACROSS THE NORTH THROUGH DAYBREAK, BUT
LIKELY PERSIST DOWNWIND OF LAKE MICHIGAN FOR A TIME AS SECONDARY
COLD FRONT PUSH ALLOWS SOME LAKE ENHANCED CLOUDINESS TO PERSIST
THIS MORNING. FROST ADVISORY REMAINS IN EFFECT FOR MUCH OF
NORTHWEST INTO PORTIONS OF NORTH CENTRAL INDIANA THIS MORNING.
THESE LOW CLOUDS HAVE COMPLICATED FROST FORECAST A BIT ACROSS
NORTHERN PORTIONS OF THE ADVISORY AREA, BUT WILL NOT MAKE ANY
CHANGES TO CURRENT FROST ADVISORY GIVEN ANTICIPATED DIMINISHING
CLOUD TRENDS OVER NEXT FEW HOURS ACROSS THE ADVISORY AREA WHICH
SHOULD ALLOW TEMPERATURES TO DROP OFF INTO THE MID-UPPER 30S.
OTHERWISE FOR TODAY, NOTABLY LESS WIND AS GRADIENT SLACKENS OFF
WITH THE APPROACH OF SURFACE ANTICYCLONE. DESPITE A GOOD DEAL OF
SUN THIS AFTERNOON, BELOW NORMAL TEMPERATURES WILL BE IN STORE
WITH PASSAGE OF THE SECONDARY COOL FRONT. LOW LEVEL TEMPS BEGIN TO
MODERATE SOME THIS AFTERNOON, BUT A BIT MORE SHALLOW MIXING TODAY
MAY COMPENSATE FOR THAT TO LIMIT HIGH TEMPS FROM THE LOW-MID 50S
NORTH TO THE MID-UPPER 50S SOUTH.
LOW LEVEL WARM ADVECTION WILL BEGIN TO STRENGTHEN TONIGHT, BUT
DEVELOPMENT OF LOW LEVEL INVERSION AND DECOUPLING SHOULD ALLOW FOR
GOOD RADIATIONAL COOLING, PARTICULARLY ACROSS THE NORTH/NORTHEAST
IN CLOSER PROXIMITY TO DEPARTING LOW LEVEL THERMAL TROUGH.
CONSIDERED ISSUING ANOTHER FROST ADVISORY FOR FAR NORTHEAST
INDIANA/SOUTHERN LOWER MICHIGAN/FAR NORTHWEST OHIO, BUT GIVEN
ONGOING HEADLINES AND CONFIDENCE ON THE MODERATE SIDE, WILL DEFER
THIS DECISION TO NEXT SHIFT.
LONG TERM
(TUESDAY THROUGH SUNDAY)
ISSUED AT 405 AM EDT MON OCT 14 2019
FOR TUESDAY, FOCUS WILL TURN TO WELL ADVERTISED POSITIVELY TILTED
PACIFIC WAVE AS IT DROPS EAST-SOUTHEAST ACROSS THE NORTHERN
PLAINS. LOW LEVEL MOISTURE TRANSPORT WILL BE INITIALLY ON THE LESS
THAN IMPRESSIVE SIDE FOR FIRST PART OF TUESDAY. A COMPACT UPPER
JET STREAK PROGRESSING THROUGH BASE OF THIS SHORT WAVE SHOULD TEND
TO GIVE THIS TROUGH MORE NEUTRAL TO SLIGHT NEGATIVE TILT AS IT
DIGS ACROSS THE SOUTHERN GREAT LAKES LATER TUESDAY NIGHT. WITH
INITIAL BETTER MOISTURE RETURN MORE HIGHLY ELEVATED FOR FIRST PART
OF TUESDAY, HAVE CONTINUED THE TREND OF THE PREVIOUS FORECAST IN
SLIGHTLY DELAYING ONSET OF POPS. WILL KEEP HIGHEST POPS FOR THE
TUESDAY EVENING PERIOD AS BETTER LOW LEVEL MOISTURE TRANSPORT
COMBINES WITH DECENT MID LEVEL LAPSE RATES FOR BETTER SHOWER
POTENTIAL. BY LATER TUESDAY EVENING, FRONTAL CIRCULATION SHOULD
ALSO MATURE AS THE UPPER TROUGH UNDERGOES THE TRANSITION TO
NEUTRAL/SLIGHT NEGATIVE TILT. GREATEST RAINFALL AMOUNTS ARE
EXPECTED EAST OF THE INTERSTATE 69 CORRIDOR WHERE ABOVE
INGREDIENTS MAY COME TOGETHER FOR A BRIEF TIME. HOWEVER, OVERALL
PROGRESSION OF THIS SYSTEM SHOULD LIMIT RAINFALL AMOUNTS.
LOW LEVEL THERMAL TROUGH DIGS ACROSS THE REGION BEHIND TUESDAY
NIGHT SYSTEM, SETTING UP A RAW AND POTENTIALLY DAMP WEDNESDAY.
LAKE INDUCED INSTABILITY WILL BE ON THE INCREASE LATER TUESDAY
NIGHT INTO WEDNESDAY WITH A POTENTIAL OF SOME SCATTERED LAKE
EFFECT/ENHANCED RAIN SHOWERS. OUTSIDE OF LAKE EFFECT, SOME PATCHY
LIGHT DRIZZLE NOT COMPLETELY OUT OF THE QUESTION AS WEAK SHORT
WAVE DIGGING THROUGH UPSTREAM PORTION OF DEPARTING MAIN UPPER
LEVEL HEIGHT MINIMUM INTERACTS WITH LINGERING SHALLOW MOISTURE.
GIVEN ABOVE FACTORS OF EXPANSIVE LOW CLOUDS/LIGHT PRECIP
POTENTIAL, HAVE COLLABORATED SLIGHT DROP IN HIGH TEMPS FOR
WEDNESDAY TO AROUND 50 DEGREES WITH SURROUNDING OFFICES. WINDY
CONDITIONS CAN ALSO BE EXPECTED LATE TUESDAY NIGHT INTO WEDNESDAY
AS LOW LEVEL LAPSE RATES STEEPEN WITH THE COLD ADVECTION.
NOT MUCH CHANGE MADE TO PREVIOUS FORECAST POST-WEDNESDAY AS THU-
FRI STILL SETS UP TO BE A RELATIVE LULL IN MORE ACTIVE PATTERN
WITH SLOW MODERATION IN TEMPERATURES. THERE COULD BE ANOTHER
WINDOW OF FROST POTENTIAL THURSDAY NIGHT/FRIDAY MORNING AS LOW
LEVEL THERMAL TROUGH BEGINS TO RETREAT. MEDIUM RANGE GUIDANCE
CONTINUES TO INDICATE EVOLUTION OF MORE AMPLIFIED LONGWAVE TROUGH
ACROSS WESTERN CONUS BY THE FIRST PART OF THE WEEKEND. WHILE
GUIDANCE IS IN AGREEMENT ON GENERAL NATURE OF UPPER FLOW PATTERN
THIS PERIOD, STILL SOME PHASING AND TIMING ISSUES WILL NEED TO BE
RESOLVED TO GET A BETTER HANDLE ON PERIODS WITH HIGHER RAIN
CHANCES. OF GREATER CONFIDENCE IS THE TRANSITION TO NEAR TO ABOVE
NORMAL TEMPERATURES FOR NEXT WEEKEND IN ADVANCE OF THIS SYSTEM.
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 120 AM EDT MON OCT 14 2019
VFR EXPECTED TO PERSIST THROUGH THE PERIOD. CURRENT CANOPY OF
CLOUDS WILL SLOWLY DISSIPATE LATER THIS MORNING AS PARENT TROUGH
LIFTS NORTHEAST AND SUBSIDENCE/DRY AIR BUILD. WINDS WILL ALSO BE
MUCH LIGHTER THIS PERIOD AS SURFACE HIGH PRESSURE BUILDS OVER THE
REGION.
IWX WATCHES/WARNINGS/ADVISORIES
IN...FROST ADVISORY UNTIL 9 AM EDT /8 AM CDT/ THIS MORNING FOR INZ003-
004-012>017-020-022>025-032.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 AM EDT THIS MORNING FOR LMZ043-046.
SYNOPSIS...MARSILI
SHORT TERM...MARSILI
LONG TERM...MARSILI
AVIATION...AGD
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