408
FXUS63 KIND 150757
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
257 AM EST FRI NOV 15 2024
KEY MESSAGES
- LOW CLOUDS AND DRIZZLE THROUGH THIS MORNING
- POTENTIAL FOR FOG AND CONTINUED LOW STRATUS TONIGHT
- RAIN CHANCES RETURN TUESDAY FOLLOWED BY A TREND TOWARD COOLER
TEMPERATURES BY THE END OF THE WEEK.
SHORT TERM (TODAY AND TONIGHT)
ISSUED AT 257 AM EST FRI NOV 15 2024
A RATHER COOL AND DREARY WEATHER PATTERN CONTINUES INTO FRIDAY FOR
MUCH OF THE STATE. LATEST SATELLITE IMAGERY SHOWS WIDESPREAD LOW
STRATUS ACROSS THE GREAT LAKES REGION AND MIDWEST IN THE WAKE OF AN
AREA OF LOW PRESSURE NEAR DETROIT. LATEST ACARS SOUNDINGS ALIGN WELL
WITH SHORT TERM MODEL GUIDANCE INDICATING A STRENGTHENING SUBSIDENCE
INVERSION ALOFT WITH A FAIRLY DEEP SATURATED LAYER FROM THE SURFACE
TO AROUND 1.5KM AGL. WEAK LIFT ASSOCIATED WITH CYCLONIC FLOW AROUND
THE AFOREMENTIONED LOW HAS RESULTED IN ISOLATED AREAS OF DRIZZLE
ACROSS THE STATE EARLY THIS MORNING. KEEPING THE CHANCE FOR DRIZZLE
IN THROUGH THE REST OF THE MORNING HOURS, WITH A SLIGHT DRYING TREND
LIKELY BY THE AFTERNOON HOURS. KEEPING THE FORECAST ON THE
PESSIMISTIC SIDE HOWEVER FOR THE REST OF THE DAY. THE LOWER SUN
ANGLE THIS TIME OF YEAR WILL STRUGGLE TO HEAT THE BOUNDARY LAYER
THROUGH THE THICK STRATUS, KEEPING MOISTURE AND LOW CLOUDS STUCK
NEAR THE SURFACE UNDER THE STRENGTHENING SUBSIDENCE INVERSION ALOFT.
THIS PATTERN IS NORMAL FOR THIS TIME OF YEAR WHERE MODELS TRY TO DRY
OUT AND HEAT THE BOUNDARY LAYER TOO FAST. THEREFORE, GOING BELOW
GUIDANCE FOR HIGHS TODAY, WITH THE COOLEST AREAS LIKELY IN NORTHERN
AND EASTERN INDIANA, WHERE CLOUDS WILL STICK AROUND THE LONGEST.
DEPENDING ON HOW FAST THE CLEARING LINE NEAR THE MISSISSIPPI RIVER
PUSHES EAST TODAY, THERE MAY BE A GOOD TEMPERATURE GRADIENT FROM
WEST TO EAST ACROSS THE AREA. IF SUNSHINE IS REALIZED FOR WESTERN
AND SW INDIANA, HIGHS MAY REACH THE MID 50S; WHEREAS AREAS STUCK
UNDER LOW CLOUDS MAY STRUGGLE TO EXCEED THE 50 DEGREE MARK.
SURFACE HIGH PRESSURE MOVES DIRECTLY OVERHEAD BY THIS EVENING BEFORE
SHIFTING NORTHEASTWARD LATER TONIGHT. A NEARLY SATURATED BOUNDARY
LAYER AND HIGH PRESSURE OVERHEAD MAY RESULT IN AREAS OF FOG AND VERY
LOW STRATUS ACROSS MUCH OF THE REGION OVERNIGHT TONIGHT. IF CLEARING
DOES TAKE PLACE IN SOME SPOTS, OPTIMAL CONDITIONS FOR RADIATIONAL
COOLING MAY LEAD TO DENSE FOG AND VERY LOW VISIBILITY IN SOME AREAS.
WILL WATCH THIS CAREFULLY AS HEADLINES MAY BE NEEDED IF THE THREAT
FOR DENSE FOG BECOMES WIDESPREAD. FOG AND LOW CLOUDS SHOULD KEEP
LOWS FROM PLUMMETING, REMAINING ELEVATED IN THE MID 40S.
LONG TERM (FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 220 PM EST THU NOV 14 2024
FOG INITIALLY SEEMED AT LEAST POSSIBLE FRIDAY NIGHT INTO SATURDAY
MORNING, BUT STRATUS LOOKS TO PERSIST INTO THIS PERIOD. LOW LEVEL
MOISTURE TRAPPED BENEATH A STRONG SUBSIDENCE INVERSION THIS TIME OF
YEAR OFTEN RESULTS IN PROLONGED STRATUS. ON THE WESTERN EDGE OF THE
STRATUS, FOG IS MORE LIKELY, BUT THIS NOW APPEARS TO BE IN ILLINOIS
OR MISSOURI. WITH PBL MOISTURE BECOMING LESS AND MIXING ON SATURDAY,
STRATUS IS LIKELY TO BREAK AROUND MIDDAY. BY THEN, MID-HIGH CLOUDS
FROM THE UPSTREAM SYSTEM AND PACIFIC MOISTURE PLUME, IN ADDITION TO
INCREASINGLY MSLP GRADIENT SHOULD LIMIT POTENTIAL FOG SUNDAY
MORNING.
WE WILL BE ON THE WINDWARD SIDE OF THE MEAN RIDGE AXIS SUNDAY, SO
TEMPERATURES WILL BE ABOUT 10 DEGREES ABOVE MID-NOVEMBER CLIMO.
WE STILL HAVE LOW PROBABILITIES OF RAIN FOR PORTIONS OF THE AREA
SUNDAY NIGHT INTO EARLY MONDAY, BUT TRENDS IN ALMOST ALL OF THE
ENSEMBLE MODELS HAVE BEEN FOR LESS COVERAGE AND FURTHER NORTH.
THIS IS TIED TO A TREND TOWARD A LESS AMPLIFIED NORTHERN STREAM
SHORTWAVE TROUGH. THERE IS STILL MODEST MOISTURE RETURN INDICATED
IN THE MODELS AND ASCENT WITH A MIDLEVEL THERMAL GRADIENT, SO WILL
LEAVE SLIGHT CHANCE IN.
STILL WARM MONDAY AND TUESDAY AS RIDGING RESURGES PRECEDING THE NEXT
SYSTEM. THERE IS LIMITED ENSEMBLE SPREAD ON LEAD SHORTWAVE TROUGH
PASSING TO OUR NORTHWEST TUESDAY. ITS ASSOCIATED WARM CONVEYER
BELT/MOISTURE SURGE SHOULD BRING A BAND OF RAIN MONDAY NIGHT AND
EARLY TUESDAY, BUT COLD ADVECTION WILL BE MINIMAL AS THIS TROUGH
WEAKENS AND MOVES EAST AT THE SAME TIME DIGGING TROUGH EVOLVES OVER
THE PLAINS.
WEDNESDAY ONWARD WE WILL ENTER A PERIOD OF LOW-MID RANGE
PRECIPITATION PROBABILITIES AND COLDER TEMPERATURES. THE SYNOPTIC-
SCALE PATTERN IS STILL SOMEWHAT UNCERTAIN AS EPS-WEIGHTED CLUSTERS
HOLD THE PLAINS TROUGH WEST LONGER, WHILE GFS IS DEEPER AND MORE
PROGRESSIVE. THIS MAY PRIMARILY IMPACT TEMPERATURES WEDNESDAY AS THE
FORMER CAMP OFFERS AN OPPORTUNITY TO WARM PRIOR TO THE ONSET OF
STRONGER COLD ADVECTION, COMPARED TO THE LATTER CAMP. DETAILS WITH
REGARDS TO PERIODS OF ENHANCED FORCING/ASCENT WITH ROTATING
VORTICITY MAXIMA ARE UNCLEAR. ALSO, COLD ADVECTION MAGNITUDE APPEARS
TO BE MODULATED BY SUBSTANTIAL HIGH-LATITUDE RIDGING IN THIS
BLOCKING PATTERN, SO WHETHER OR NOT TEMPERATURES ARE COLD ENOUGH FOR
SNOW LATE NEXT WEEK IS NOT TOTALLY CLEAR. TEMPERATURES WILL BE
MARGINAL. STEEP LAPSE RATES BENEATH THE COLD CORE LOW WOULD SUPPORT
A MORE SHOWERY REGIME.
DAY 8-14 WILL START OFF WITH TROUGHING, AND THERE APPEARS TO BE SOME
SIGNAL FOR THIS TO PERSIST. NEAR TO BELOW NORMAL TEMPERATURES
AND NEAR NORMAL PRECIPITATION WOULD RESULT.
AVIATION (06Z TAF ISSUANCE)
ISSUED AT 1233 AM EST FRI NOV 15 2024
IMPACTS:
- MVFR/IFR CIGS AND VIS SLOWLY IMPROVE AFTER 15Z THIS MORNING
DISCUSSION:
MVFR TO IFR CIGS AND VIS WILL CONTINUE THROUGH THE EARLY MORNING
HOURS AT ALL TAF SITES IN CENTRAL INDIANA. LATEST ACARS SOUNDINGS
AND SATELLITE IMAGERY SHOW LOW LEVEL MOISTURE AND CLOUDS TRAPPED
WITHIN THE LOWEST 1KM AGL WITH THE BACK EDGE OF THE CLOUD DECK STILL
ALONG THE MISSISSIPPI RIVER. CYCLONIC FLOW AROUND A DEPARTING AREA
OF LOW PRESSURE NEAR DETROIT WILL KEEP WINDS OUT OF THE NW AROUND 10
KTS OVERNIGHT WITH THE CHANCE FOR DRIZZLE IN SUCH A SATURATED
ENVIRONMENT. PATCHY AREAS OF FOG MIXED IN WITH THE LOW STRATUS MAY
REDUCE VISIBILITY AT TIMES THROUGH THE LATE MORNING HOURS.
LOWER CONFIDENCE EXISTS WITH HOW FAST CONDITIONS IMPROVE DURING THE
DAY. POTENTIAL EXISTS FOR MVFR CIGS TO STICK AROUND MUCH OF THE
AFTERNOON, WHICH IS CERTAINLY POSSIBLE DUE TO THE LOWER SUN ANGLE
THIS TIME OF YEAR. THE CURRENT TAF CALLS FOR CIGS TO RAISE TO VFR
LEVELS BY LATE AFTERNOON/EARLY EVENING; HOWEVER WILL HAVE TO KEEP A
CLOSE EYE ON SATELLITE TRENDS LATER TODAY AND ADJUST TAFS
ACCORDINGLY.
IND WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...CM
LONG TERM...BRB
AVIATION...CM
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