Beach Hazards Statement 11, NWS Detroit, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
352 AM EDT THU AUG 20 2015

.SHORT TERM... TODAY AND TONIGHT

A TEXTBOOK FRONTAL ENHANCEMENT OF SHOWERS AND A FEW THUNDERSTORMS IS
UNDERWAY OVER SE MICHIGAN DURING THE EARLY MORNING. THE POTENTIAL
FOR LOCALLY HEAVY RAINFALL WILL BE THE PRIMARY CONCERN WITH THIS
PATTERN UNTIL IT EXITS SE MICHIGAN BY MID MORNING. BREEZY WEST WIND
IN POST FRONTAL COLD ADVECTION WILL THEN TAKE OVER FOR THE REST OF
THE DAY WITH A FEW INSTABILITY SHOWERS POSSIBLE DURING PEAK HEATING.
THIS WILL LEAD TO A CLEARING TREND TONIGHT WITH COOLER AND MUCH LESS
HUMID CONDITIONS SETTLING OVER THE REGION.

REGIONAL RADAR COMPOSITE HAS INDICATED POCKETS OF DEEPER CONVECTION
AND HEAVIER RAINFALL ALONG AND AHEAD OF THE SURFACE FRONT. RADAR
ESTIMATES HAVE BEEN SLIGHTLY UNDER SURFACE OBSERVATIONS BUT BOTH
HAVE GENERALLY STAYED AROUND 0.5 INCH FOR 1 HOUR TOTALS WITH
RUNNING AVERAGE 3 HOUR TOTALS OF AROUND 1 INCH. THE PATTERN HAS
BEEN AND WILL CONTINUE TO QUICKLY TRANSITION TOWARD A HYBRID
ELEVATED CONVECTION/STRATIFORM SCENARIO WITH PEAK RAINFALL RATES
CLOSER TO 0.25 INCH PER HOUR. THIS WILL BE MONITORED THROUGH THE
MORNING COMMUTE WITH THE POTENTIAL FOR AN URBAN FLOOD ADVISORY
ABOUT ALL THAT MIGHT BE ANTICIPATED BASED ON BEHAVIOR OF POST PEAK
RATES BEFORE THE BACK EDGE OF THE RAIN EXITS SE MICHIGAN AROUND
MID MORNING.

UPSTREAM OBSERVATIONS IN SURFACE ANALYSIS AND SATELLITE IMAGERY OVER
THE MIDWEST INDICATE CONSIDERABLE COVERAGE OF STRATOCU WITHIN THE
COOLER AND LESS HUMID AIR SPREADING INTO THE REGION POST FRONT.
EXPECT THIS WILL EASILY SPREAD OVER LOWER MICHIGAN AND PERSIST
THROUGH THE DAY THANKS TO SURFACE HEATING UNDER STEEP LAPSE RATES
BELOW 700 MB. BOTH SYNOPTIC AND MESOSCALE MODEL SOUNDINGS INDICATE
ENOUGH CAPE DENSITY (~150 J/KG) TO SUPPORT ISOLATED - SCATTERED
LIGHT SHOWERS DURING THE AFTERNOON AS IN THE GOING FORECAST. THE
BOUNDARY LAYER WILL ALSO BECOME WELL MIXED AS AFTERNOON TEMPERATURES
REBOUND BUT ONLY INTO THE LOWER TO MID 70S. MIXING WILL TAP INTO
WESTERLY GUSTS NEAR 30 MPH BEFORE SETTLING DOWN AFTER SUNSET AS THE
SAME MODEL SOUNDINGS SHOW A CONVINCING SURFACE BASED INVERSION
DEVELOPING DURING THE EVENING. LIGHT SOUTHWEST SURFACE GRADIENT WIND
WILL LINGER AROUND 5 KNOTS OVERNIGHT WHICH IS ON THE HIGH SIDE FOR
FOG DEVELOPMENT EVEN OVER THE WET GROUND CONDITIONS. EVEN IF THE
WIND DIES OFF WITH DECOUPLING...FORECAST SOUNDINGS INDICATE A VERY
SHALLOW MOISTURE PROFILE NOT SUPPORTIVE OF MUCH FOG POTENTIAL
THROUGH SUNRISE FRIDAY.

&&

.LONG TERM...FRIDAY THROUGH TUESDAY

PROGRESSIVE LONGWAVE PATTERN WILL SEE LOW HEIGHT TROUGH/ANOMALY LIFT
RAPIDLY NORTHEASTWARD TOWARDS JAMES BAY WITH BUILDING GEOPOTENTIAL
HEIGHTS FOR THE CENTRAL GREAT LAKES. THE REGION WILL NOT EXPERIENCE
A RETURN TO A GENUINE LONGWAVE RIDGE...RATHER AN AMPLIFYING
SHORTWAVE RIDGE STRUCTURE HEADING INTO THE WEEKEND.

SURFACE HIGH PRESSURE CENTERED OVER PORTIONS OF OHIO AND LAKE ERIE
WILL BE IN SOLID CONTROL OF THE WEATHER FRIDAY ACROSS SOUTHEASTERN
MICHIGAN. LOW HUMIDITY WILL BE THE ITEM OF NOTE AS SURFACE DEWPOINTS
WILL ONLY BE OBSERVED IN THE LOWER 50S. SUNSHINE AND PICTURE PERFECT
WEATHER. THE DRIER AIRMASS WILL LEAD TO A GOOD DIURNAL TEMPERATURE
RESPONSE WITH HIGHS IN THE UPPER 70S.

RETURN SOUTHWESTERLY FLOW WILL KICK WARM AIR ADVECTION INTO GEAR
FRIDAY NIGHT AND INTO THE DAY ON SATURDAY. TWO THINGS WILL KEEP THE
WEATHER DRY DESPITE THE WAA...1. STABLE MIDLEVELS BETWEEN 9 AND 16
KFT AGL...2. DOWNRIGHT LACK OF ANY SIGNIFICANT MOISTURE ADVECTION.
WITH SUNSHINE AND WARMER AIR ADVECTING INTO THE
REGION...EXPECTATIONS ARE FOR TEMPERATURES TO CLIMB ABOVE THE 80
DEGREE MARK.

MODEL DATA IS STILL ADVERTISING A DYNAMIC UPPER LEVEL LOW PRESSURE
SYSTEM SLIDING ACROSS THE UPPER PLAINS SATURDAY NIGHT AND PUSHING
INTO THE GREAT LAKES SUNDAY WHILE ON A NEGATIVE TILT. OVERALL...THE
SYSTEM LOOKS GREAT BOTH FROM AN UPPER LEVEL JET AND CYCLONIC
VORTICITY STRUCTURE PERSPECTIVE. INHERENT TIMING UNCERTAINTIES
ALWAYS EXIST...BUT EVIDENCE POINTS TO A SUNDAY EVENING TIMING FOR
PRECIPITATION ONSET. THE FEELING IS THERE IS ACTUALLY HIGHER THAN
NORMAL CONFIDENCE THAT THE GREATER PORTION OF DAYLIGHT SUNDAY WILL
REMAIN DRY. HIGHS SUNDAY WILL AGAIN MAKE A RUN AT THE 80 DEGREE
MARK. ENJOY THE WEEKEND.

&&

.MARINE...

THE SURFACE COLD FRONT IS IN THE PROCESS OF PUSHING ACROSS
SOUTHEASTERN MICHIGAN EARLY THIS MORNING. STRONG WESTERLY FLOW WILL
DEVELOP TODAY IN THE POST COLD FRONT ENVIRONMENT. WEST TO SOUTHWEST
WINDS ARE EXPECTED TO INCREASE INTO THE 20 TO 30 KNOT RANGE FOR ALL
MARINE AREAS. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR ALL
NEARSHORE WATERS ADJACENT TO SOUTHEASTERN MICHIGAN. OFF SHORE FLOW
WILL MINIMIZE THE WAVE HEIGHTS IN THE NEARSHORE ZONES WITH THE
EXCEPTION OF SAGINAW BAY WHERE THE FLOW WILL BE ALONG THE AXIS OF
THE BAY ALLOWING WAVE TO BUILD. SURFACE HIGH PRESSURE WILL THEN
BUILD INTO THE AREA FOR FRIDAY AND MUCH OF THE UPCOMING WEEKEND.
LIGHTER FLOW AND SUNSHINE WILL LEAD TO AN OUTSTANDING STRETCH OF
MARINE WEATHER CONDITIONS RIGHT THROUGH MUCH OF THE DAY ON SUNDAY.

&&

.AVIATION...ISSUED 1157 PM EDT WED AUG 19 2015

INCREASING POTENTIAL FOR SHOWERS OVERNIGHT AS A STRENGTHENING
FRONTAL ZONE ENTERS THE REGION.  LIMITED POTENTIAL FOR EMBEDDED
THUNDER...LIMITED COVERAGE PRECLUDES A MENTION.  ENVIRONMENT WILL BE
SUPPORTIVE OF AT LEAST PERIODIC EPISODES OF HEAVIER RAINFALL...
LEADING TO MVFR CONDITIONS.  THIS MOISTURE WILL EXIT TO THE EAST BY
MID MORNING THURSDAY /10Z-12Z/.  GUSTY POST-FRONTAL SOUTHWESTERLY
CONDITIONS WILL EMERGE AS DAYTIME HEATING ENSUES ON THURSDAY.  GUSTS
INTO THE 25 KNOT RANGE FOR THE AFTERNOON PERIOD.

FOR DTW...INCREASING COVERAGE OF SHOWERS EXPECTED DURING THE
OVERNIGHT PERIOD. WEAK INSTABILITY WILL MAINTAIN THE POTENTIAL FOR
SOME EMBEDDED THUNDERSTORMS.  HOWEVER THE LOW PROBABILITY AND
QUESTIONABLE DURATION/TIMING WILL PRECLUDE ANY DEFINED MENTION AT
THIS STAGE.  PERIODIC MVFR CONDITIONS AS THIS MOISTURE WORKS
THROUGH.

//DTW THRESHOLD PROBABILITIES...

* MEDIUM FOR CEILINGS BELOW 5000 FT TONIGHT...AND THURSDAY.

* LOW FOR THUNDERSTORMS TONIGHT.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...NONE.

LAKE HURON...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 10 PM EDT THIS
     EVENING FOR LHZ441>443.

     SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR LHZ421-422.

LAKE ST CLAIR...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 10 PM EDT THIS
     EVENING FOR LCZ460.

MICHIGAN WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 10 PM EDT THIS
     EVENING FOR LEZ444.

&&

SHORT TERM...BT
LONG TERM....CB
MARINE.......CB
AVIATION.....MR

YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
942 PM EDT WED AUG 19 2015

MIZ047>049-053>055-060>063-068>070-075-076-082-083-210145-
MIDLAND-BAY-HURON-SAGINAW-TUSCOLA-SANILAC-SHIAWASSEE-GENESEE-LAPEER-
ST. CLAIR-LIVINGSTON-OAKLAND-MACOMB-WASHTENAW-WAYNE-LENAWEE-MONROE-
942 PM EDT WED AUG 19 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST
MICHIGAN.

.DAY ONE...TONIGHT

THERE IS AN INCREASING CHANCE FOR SHOWERS TONIGHT. THE POTENTIAL
EXISTS FOR THESE SHOWERS TO CONTAIN SOME EMBEDDED THUNDERSTORMS.
WHILE STORMS ARE NOT EXPECTED TO BE SEVERE OVERNIGHT...THEY MAY
RESULT IN TORRENTIAL RAINFALL. THIS COULD LEAD TO FLOODINGIN THE
NORMALLY FLOOD PRONE URBAN AREAS. STORM MOTION WILL BE SOUTHWEST
TO NORTHEAST AT 35 MPH.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THERE IS A CHANCE OF THUNDERSTORMS SUNDAY AS THE NEXT COLD FRONT
MOVES INTO THE REGION.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT.

LCZ460-LEZ444-LHZ361>363-421-422-441>443-462>464-210145-
LAKE ST. CLAIR-
MICHIGAN WATERS OF LAKE ERIE FROM DETROIT RIVER TO NORTH CAPE MI-
LAKE HURON FROM 5NM EAST OF MACKINAC BRIDGE TO PRESQUE ISLE LT
BEYOND 5 NM OFF SHORE-
LAKE HURON FROM PRESQUE ISLE LIGHT TO STURGEON POINT MI BEYOND 5NM
OFF SHORE-
LAKE HURON FROM STURGEON POINT TO ALABASTER MI BEYOND 5NM OFF SHORE-
OUTER SAGINAW BAY SW OF ALABASTER TO PORT AUSTIN MI TO INNER SAGINAW
BAY-INNER SAGINAW BAY SW OF POINT AU GRES TO BAY PORT MI-
PORT AUSTIN TO HARBOR BEACH MI-HARBOR BEACH TO PORT SANILAC MI-
PORT SANILAC TO PORT HURON MI-
LAKE HURON FROM PORT AUSTIN TO HARBOR BEACH BEYOND 5NM OFF SHORE-
LAKE HURON FROM HARBOR BEACH TO PORT SANILAC BEYOND 5NM OFF SHORE-
LAKE HURON FROM PORT SANILAC TO PORT HURON BEYOND 5NM OFF SHORE-
942 PM EDT WED AUG 19 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF LAKE ERIE...LAKE
HURON AND LAKE ST CLAIR.

.DAY ONE...TONIGHT

A SMALL CRAFT ADVISORY IS IN EFFECT TODAY AND TONIGHT FOR SAGINAW
BAY. PLEASE SEE THE LATEST MARINE FORECASTS AND STATEMENTS FOR
DETAILS.

SCATTERED THUNDERSTORMS THROUGH TONIGHT. A FEW STORMS COULD
PRODUCE WIND GUSTS TO 40 KNOTS ALONG WITH TORRENTIAL RAINFALL.
STORM MOTION WILL BE SOUTHWEST TO NORTHEAST AT 30 KNOTS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

A SMALL CRAFT ADVISORY IS IN EFFECT FOR SAGINAW BAY THROUGH
THURSDAY EVENING. PLEASE SEE THE LATEST MARINE FORECASTS AND
STATEMENTS FOR DETAILS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT.

YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

MR