833
FXUS63 KAPX 161730
AFDAPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
130 PM EDT WED OCT 16 2013
.SYNOPSIS...
ISSUED AT 404 AM EDT WED OCT 16 2013
LINGERING MOISTURE BEHIND A DEPARTING AREA OF LOW PRESSURE WILL
BRING ADDITIONAL RAIN SHOWERS TO NORTHERN MICHIGAN TODAY. AFTER A
BRIEF BREAK IN THE WEATHER FOR MUCH OF THURSDAY...LAKE EFFECT RAIN
SHOWERS ARE EXPECTED FRIDAY INTO THE WEEKEND...ALONG WITH COOLER
TEMPERATURES.
&&
.UPDATE...
ISSUED AT 130 PM EDT WED OCT 16 2013
GOING FORECAST IN PRETTY GOOD SHAPE...WITH A SMATTERING OF SHOWERS
CONTINUING TO WORK THROUGH THE REGION. THE MOST PRONOUNCED AREA OF
THESE IS ALONG A SURFACE TROUGH AXIS JUST NOW WORKING THROUGH
NORTHWEST LOWER...WITH MORE DIURNALLY DRIVEN/LAKE ENHANCED
ACTIVITY FARTHER NORTH INTO EASTERN UPPER AND A COUPLE MORE AXES
OF LIGHT SHOWERS/DRIZZLE INTO NORTHEAST LOWER. THAT GENERAL SETUP
WILL CONTINUE THROUGH LATE AFTERNOON...WITH LOTS OF CLOUDS OUTSIDE
OF THE RAIN AND TEMPS BASICALLY REMAINING FLATLINED.
UPDATE ISSUED AT 949 AM EDT WED OCT 16 2013
NO BIG CHANGES NEEDED TO THE GOING FORECAST...WITH THE BASIC
FLAVOR OF A CHILLY...DAMP...AND SHOWERY OCTOBER DAY LOOKING JUST
FINE. SHARP UPPER TROUGH AXIS IS CURRENTLY PIVOTING INTO LAKE
MICHIGAN...WITH ITS ASSOCIATED SURFACE TROUGH FEATURE JUST NOW
CROSSING MID LAKE. CURRENTLY SEEING A NICE FLARE-UP OF SHOWERS
ALONG THIS FEATURE...AND EXPECT THIS TREND WILL CONTINUE...FUELED
ALSO BY INCREASING LAKE INSTABILITY THROUGH THE AFTERNOON AS H8
TEMPS SLOWLY DROP TOWARD 2C. CURRENT FORECAST OF LIKELY TO
CATEGORICAL SHOWERS SHOULD WORK THROUGH THE DAY...THOUGH WITH
ACTIVITY INCREASINGLY CONFINED TO NORTHERN LOWER AS THE LOWER
LEVEL TROUGH PASSES AND SOMEWHAT DRIER AIR TRIES TO FILTER TOWARD
THE EASTERN U.P. IN LINE WITH THE SETUP...HAVE ADDED A WATERSPOUT
MENTION BACK TO MUCH OF NORTHERN LAKE MICHIGAN AND PARTS OF LAKE
HURON...AS CURRENT PARAMETERS LINE UP NICELY WITH FAVORED NOMOGRAM
SETUPS...PARTICULARLY WITH ADDED LOW LEVEL CONVERGENCE ALONG THE
TROUGH AXIS TO HELP FOCUS VORTICITY/SPIN. TEMPS TODAY SHOULD
BASICALLY DO LITTLE...PERHAPS NUDGING UPWARD A COUPLE OF
DEGREES...BUT HOLDING NOT TERRIBLY FAR FROM TYPICAL MID OCTOBER
VALUES IN THE LOW TO MID 50S.
UPDATE ISSUED AT 629 AM EDT WED OCT 16 2013
SHOWERS STARTING TO DEVELOP ON TARGET ACROSS NORTHWEST LOWER AS
FORCING FROM UPSTREAM VORTICITY CENTER SPREADS ACROSS LAKE
MICHIGAN. SO NO MAJOR FORECAST CHANGES FORTHCOMING.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 404 AM EDT WED OCT 16 2013
SYNOPSIS...MIDNIGHT SURFACE ANALYSIS SHOWS 1004MB OCCLUDING LOW
CENTER OVER SOUTHERN UPPER MICHIGAN...COLD/OCCLUDED FRONT ARCS SOUTH
ACROSS WESTERN LOWER MICHIGAN...WARM FRONT THROUGH THE STRAITS
REGION...AND A SECONDARY TROUGH AXIS EXTENDING BACK TO THE SOUTHWEST
ACROSS NORTHWEST WISCONSIN/CENTRAL IOWA. ELONGATED POSITIVE TILT
UPPER SHORT WAVE TROUGH/POTENTIAL VORTICITY ANOMALY EXTENDS FROM THE
UPPER GREAT LAKES SOUTHWEST TO THE CENTRAL ROCKIES/GREAT BASIN.
WATER VAPOR IMAGERY INDICATES A SEVERAL VORTICITY CENTERS UPSTREAM
ACROSS WISCONSIN/MINNESOTA...AND ANOTHER NORTHWEST OF LAKE SUPERIOR
(DRY SLOT ALSO PUNCHING INTO THE LOWER PENINSULA). ARRIVAL OF DRIER
MID LEVEL AIR HAS PUSHED THE MORE WIDESPREAD SHOWERS EAST OF LOWER
MICHIGAN...THOUGH A BAND OF SHOWERS COINCIDENT WITH THE COLD FRONT
WAS CROSSING LOWER MICHIGAN...WITH A BROKEN AREA OF SHOWERS ACROSS
EASTERN LAKE SUPERIOR/WESTERN UPPER MICHIGAN WITHIN LOW/MID LEVEL
DEFORMATION AXIS. A NARROW AREA OF CLEARING WAS PUSHING INTO
NORTHWEST LOWER...AND MAY SEE SOME BREAKS IN THE CLOUDS SPREAD
ACROSS NORTHERN LOWER MICHIGAN FOR A TIME DURING THE PRE-DAWN HOURS
THOUGH ANY CLEARING WILL BE SHORT LIVED.
2-3MB/3H PRESSURE FALLS COINCIDENT WITH AND EAST/NORTHEAST OF THE
OCCLUDED LOW SUGGEST A TRACK ACROSS EASTERN UPPER OVER THE NEXT
COUPLE OF HOURS AND MAY STRENGTHEN A COUPLE MORE MILLIBARS AS WELL.
ASSOCIATED COLD FRONT EXPECTED TO CLEAR LOWER MICHIGAN AROUND
DAYBREAK...SECONDARY TROUGH HANGING BACK ACROSS WISCONSIN WILL
ROTATE ACROSS THE FORECAST AREA THIS AFTERNOON. WISCONSIN VORTICITY
CENTER WILL CROSS LOWER MICHIGAN LATER THIS MORNING...WITH SOME WEAK
HEIGHT RISES EXPECTED TONIGHT. MAIN FORECAST CONCERN FOR THE SHORT
TERM PERIOD WILL DEAL WITH PRECIPITATION CHANCES AS THESE FEATURES
MOVE THROUGH.
TODAY/TONIGHT...A LULL IN THE PRECIPITATION EARLY THIS MORNING WILL
RAMP BACK UP AGAIN AS THE MORNING PROGRESSES DUE TO A COMBINATION OF
FACTORS: 1)ARRIVAL OF SOME DEEPER MOISTURE ASSOCIATED WITH
WISCONSIN VORTICITY CENTER. 2)BROKEN BAND OF DEFORMATION ZONE
SHOWERS ACROSS WESTERN UPPER WILL ROTATE IN LATER THIS
MORNING...WITH STRONGEST LOW LEVEL FORCING EXPECTED TO REMAIN OVER
NORTHERN PORTIONS OF THE FORECAST AREA. 3)COMBINATION OF DIURNAL
AND SOME LAKE INDUCED INSTABILITY WITH COLDER AIR SPREADING ACROSS
THE UPPER GREAT LAKES...AND LOW LEVEL CYCLONIC FLOW/ASSOCIATED
CONVERGENCE SHOULD INCREASE SHOWER COVERAGE BY LATE MORNING/
AFTERNOON PARTICULARLY ACROSS NORTHEAST LOWER. SO A CLOUDY/SHOWERY
DAY EXPECTED TO DEVELOP...A BIT BREEZY AS WELL WHICH WILL MAKE IT
FEEL THAT MUCH MORE COOL/DAMP AS TEMPERATURES NOT EXPECTED TO MOVE
UPWARD A WHOLE LOT THIS AFTERNOON.
SYNOPTIC COMPONENT TO PRECIPITATION CHANCES WANES THIS AFTERNOON AND
TONIGHT...AND WITH LOSS OF DIURNAL HEATING COMPONENT WILL BE LEFT
WITH LINGERING LAKE INSTABILITY WITH 850MB TEMPERATURES FLIRTING
WITH 0C. THINK PRECIPITATION COVERAGE WILL WANE DURING THE
EVENING...BUT DON'T WANT TO BE TOO QUICK IN COMPLETELY DRYING THINGS
OUT OVERNIGHT GIVEN THE TYPICAL INERTIA ASSOCIATED WITH LAKE EFFECT
EVENTS.
&&
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 404 AM EDT WED OCT 16 2013
A SYSTEM TRACKING BY TO OUR SOUTH WILL BRING A CHANCE FOR SHOWERS
ACROSS SOUTHERN ZONES THURSDAY. OTHERWISE...A SHORT BREAK IN THE
ACTION IS EXPECTED THROUGH MUCH OF THURSDAY NIGHT AS SHORT WAVE
RIDGING BUILDS INTO THE REGION. MEANWHILE...AN OMEGA BLOCK TYPE
RIDGE ACROSS THE EASTERN PACIFIC WILL FORCE DOWNSTREAM TROUGHING
ACROSS THE GREAT LAKES REGION FRIDAY THROUGH EARLY NEXT WEEK. THIS
WILL LEAD TO SHOWERY...DAMP AND VERY COOL CONDITIONS...PERHAPS EVEN
WITH THE FIRST WET SNOWFLAKES OF THE YOUNG SEASON. THE MAIN LONG
TERM FORECAST CONCERNS CONTINUE TO REVOLVE AROUND POPS AND HIGH
TEMPERATURES THROUGH THE ENTIRE FORECAST PACKAGE.
THURSDAY INTO THURSDAY NIGHT...LOW PRESSURE TRACKS BY TO OUR SOUTH.
SHORT TERM MODELS DIFFER ON THE NORTHWARD EXTENT OF MOISTURE...SO
WILL CONTINUE WITH ONGOING LOW CHANCE POPS FOR RAIN SHOWERS ACROSS
SOUTHERN ZONES. MEANWHILE...SHORT WAVE RIDGING BUILDS IN FROM THE
WEST WHICH IS EXPECTED TO TEMPORARILY DRY OUT THE REMAINDER OF THE
REGION YIELDING PARTLY CLOUDY SKIES. HIGHS IN THE LOWER AND MIDDLE
50S. LOWS IN THE 30S TO AROUND 40.
FRIDAY THROUGH SUNDAY...EXTENDED MODELS CONTINUE TO BE IN AGREEMENT
THAT A LARGE UPPER LEVEL RIDGE ACROSS THE EASTERN PACIFIC FORCES
DOWNSTREAM TROUGHING ACROSS THE GREAT LAKES REGION. THIS WILL BE THE
COOLEST AIR MASS OF THE YOUNG SEASON LEADING TO A FEW ROUNDS OF LAKE
DRIVEN SHOWERS (HAVE INCREASED POPS WITH NUMEROUS COVERAGE DOWNWIND
OF LAKE MICHIGAN AND SCATTERED COVERAGE ELSEWHERE). IN
ADDITION...SHORT WAVE ENERGY DROPPING DOWN THROUGH THE FLOW WILL
BRING REINFORCING SHOTS OF CHILLY AIR WHILE ENHANCING SHOWER
ACTIVITY. UNFORTUNATELY THE TIMING AND TRACK OF INDIVIDUAL WAVES
REMAINS FAIR TO POOR AT BEST...LEAVING CRUCIAL DETAILS LIKE THE
CHANGING FLOW REGIMES IN QUESTION...THOUGH A GENERAL WESTERLY FLOW
IS EXPECTED. THERE STILL COULD END UP BEING A FEW WET SNOWFLAKES
ACROSS THE HIGHER TERRAIN OVER THE WEEKEND AS 850 MB TEMPS FALL TO
BETWEEN -2 AND -4 C...MAINLY ON SUNDAY. HIGHS FRIDAY RANGING FROM
THE UPPER 40S NORTH TO THE UPPER 50S SOUTHEAST THEN ONLY THE MIDDLE
40S TO LOWER 50S OVER THE WEEKEND. LOWS MAINLY IN THE 30S.
MONDAY THROUGH WEDNESDAY...MORE OF THE SAME WITH THE UPPER TROUGH
REMAINING IN PLACE ACROSS THE REGION...BRINGING CONTINUED SHOWER
CHANCES AS MORE PIECES OF ENERGY MOVE THROUGH THE FLOW. CONTINUED
CHILLY WITH HIGHS RANGING FROM THE MIDDLE 40S TO LOWER 50S AND LOWS
MAINLY IN THE 30S...THOUGH WE COULD SEE SOME SPOTS AWAY FROM THE
LAKES THAT MANAGE TO CLEAR OUT EASILY FALLING INTO THE 20S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 130 PM EDT WED OCT 16 2013
A MORE TYPICAL OCTOBER AVIATION FORECAST...WITH LOTS OF MAINLY
MVFR CEILINGS EXPECTED FOR THE TERMINAL SITES RIGHT ON THROUGH
TONIGHT...AS AN UPPER TROUGH AND COLDER AIR CONTINUE TO WORK
THROUGH THE REGION. SHOULD CONTINUE TO SEE OFF AN ON RAIN SHOWERS
IMPACT MAINLY PLN/TVC/MBL RIGHT ON INTO THE EVENING AS SYNOPTIC
SHOWERS GIVE WAY TO THOSE OF THE LAKE EFFECT VARIETY. THOSE SHOULD
GRADUALLY WIND DOWN LATE TONIGHT INTO FRIDAY...WITH CEILINGS EVER
SO SLOWLY LIFTING BACK TOWARD LOW END VFR.
&&
.MARINE...
ISSUED AT 404 AM EDT WED OCT 16 2013
HAVE REARRANGED SOME OF THE SMALL CRAFT ADVISORIES THIS MORNING...
MAINLY ADJUSTING THE LAKE HURON ZONES FOR EXPECTED TRENDS. WINDS
WILL SWING AROUND FROM SOUTHERLY TO NORTHWEST BY TONIGHT...WILL
REMAIN GUSTY ON LAKE MICHIGAN AND SOUTHERN LAKE HURON ZONES
TODAY...AND AS WINDS BECOME NORTHWEST TONIGHT COASTAL CONVERGENCE
WILL HELP KEEP WINDS UP IN THE STRAITS TO PRESQUE ISLE LIGHT
NEARSHORE ZONE ON LAKE HURON. WINDS EXPECTED TO DIMINISH BY
THURSDAY MORNING.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR LHZ345.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LHZ348-349.
SMALL CRAFT ADVISORY UNTIL 5 AM EDT THURSDAY FOR LHZ347.
LM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR LMZ323-342-
344>346.
LS...NONE.
&&
$$
UPDATE...LAWRENCE
SYNOPSIS...AJS
SHORT TERM...JPB
LONG TERM...AJS
AVIATION...LAWRENCE
MARINE...JPB