Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 130751
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
351 AM EDT SUN JUL 13 2014

.SHORT TERM...TODAY AND TONIGHT

FIRST ORDER OF BUSINESS IS DEALING WITH THE CURRENT COLD FRONT AND
RESULTANT AREA OF SHOWERS AND THUNDERSTORMS WORKING THROUGH THE
AREA. SEVERE THREAT IS PRETTY MUCH GONE AS THE REFLECTIVITY
SIGNATURE IS TRANSITIONING TO THAT OF AN AREA OF SHOWERS WITH
EMBEDDED THUNDERSTORMS. IR SATELLITE LOOP SHOWS CLOUD TOPS WARMING
OVERHEAD BACKING UP THE DIMINISHING TREND. CURRENT RADAR TRENDS ARE
SUGGESTING A QUICKER END TO THE ACTIVITY THIS MORNING AS THE BACK
EDGE IS ALREADY HALFWAY THROUGH GRR CWA AS OF 07Z. SO STARTED OFF BY
TRIMMING MOST OF THE RAIN MENTION OUT OF THE FORECAST AFTER 12Z.
ALSO SHUNTED THE LINGERING SHOWERS ALONG THE FRONT SOUTH OF THE AREA
TODAY AS IT APPEARS THE SYSTEM WILL LAY THE FRONT OUT ACROSS OHIO
AND INDIANA VS EXTREME SOUTHERN MI. THE RISK OF FLOODING IS
DECREASING RAPIDLY AS WELL. THE HEAVIEST SHOWERS WERE MAINLY NORTH
OF THE I69 CORRIDOR AND CURRENT RADAR ESTIMATES ARE ONLY AROUND AN
INCH FROM THE ACTIVITY THUS FAR WITH THE BACK EDGE NOT FAR OFF.
WILL CONTINUE TO MONITOR THOUGH.

FOR TODAY...WITH THE INITIAL FRONT HAVING PASSED THROUGH THE AREA WE
WILL BE LEFT WITH A DRIER AIRMASS WITH PWATS DROPPING FROM 2 INCHES
DOWN TO NEAR 1 INCH BY THE AFTERNOON. TEMPERATURES WILL STILL BREAK
THE 80 DEGREE MARK AS WE START THE DAY WITH 850MB TEMPS STEADILY
AROUND 15C INTO THE AFTERNOON HOURS AS WE FALL INTO WESTERLY FLOW
BEHIND THE FRONT. WITH PLENTY OF SUBSIDENCE BEHIND THE FRONT AND
VERY DRY AIR ALOFT...WE SHOULD GET A FAIR AMOUNT OF SUN BEFORE THE
AMPLE LL MOISTURE GETS UTILIZED BY DIURNAL HEATING TO RESULT IN A
DECENT CU FIELD. THE MORE NOTABLE TEMPERATURE DROP WILL COME WITH
THE SECOND COLD FRONT TO GET SENT THROUGH THE REGION BY THE DEEP
CLOSED UPPER LOW OVER CENTRAL CANADA AFTER 00Z THIS EVENING. 500 MB
TEMPS AROUND -6C DURING THE AFTERNOON WILL DROP TO -11C BY 12Z
MONDAY AS THE -22C COLD CORE ROTATES INTO NORTHERN MN/WI. WITH THE
HIGH DEWPOINTS PUSHED SOUTH...TEMPS WILL FALL TO AROUND 55 TO 60
DEGREES TONIGHT. WILL NEED TO WATCH THE SAGINAW VALLEY AND THUMB FOR
POTENTIAL FOG DEVELOPMENT AS DEWPOINTS WILL ALSO HANG OUT IN THE
MID/UPPER 50S WITH PLENTY OF SFC MOISTURE FROM THE SATURDAY NIGHT
SHOWERS/THUNDERSTORMS. SOME HIRES RUNS ARE TRYING TO SPARK A FEW
SHOWERS ALONG THE SECOND COLD FRONT AROUND 00Z THIS EVENING BUT THE
RESIDENT AIRMASS WILL BE VERY DRY BY THAT POINT WITH THE EXCEPTION
OF THE THIN LAYER FROM ABOUT 850-750MB. WILL HOLD ONTO THE INHERITED
DRY FORECAST.

&&

.LONG TERM...MONDAY THROUGH SATURDAY

A LARGE UPPER LOW IS CLEARLY VISIBLE ON WATER VAPOR IMAGERY OVER
WESTERN QUEBEC EARLY THIS MORNING. A SIGNIFICANT SHORTWAVE SPINNING
OFF THIS LARGE LOW WILL DIVE SOUTH THROUGH THE CENTRAL GREAT LAKES
LATE MONDAY INTO MONDAY NIGHT. THIS LOW WILL BRING A POWERFUL COLD
FRONT WITH IT...DROPPING 850 MB TEMPERATURES FROM THE MIDDLE TEENS
TO AROUND 5 DEGREES BY MONDAY NIGHT. THIS WILL BRING A VERY COLD
AIRMASS TO THE CENTRAL GREAT LAKES TUESDAY AND WEDNESDAY. THIS
AIRMASS COULD LEAD TO RECORD LOW MAXES FOR WEDNESDAY AS RECORDS THIS
DAY ARE EASILY BEATABLE.

MONDAY WILL START OUT DRY BEFORE THE AFOREMENTIONED TROUGH AND COLD
FRONT DIVE SOUTH. ALTHOUGH THERE WILL BE A CHANCE OF RAIN MONDAY
AFTERNOON AHEAD OF THE SHORTWAVE...THE BEST CHANCES WILL BE MONDAY
EVENING WHEN THE SHORTWAVE TRACKS THROUGH SOUTHEAST MICHIGAN.
UNDERNEATH THE DOME OF COLD AIR RAIN CHANCES WILL CONTINUE TUESDAY
AND WEDNESDAY...WITH THE BEST POPS DURING THE DAY GIVEN THE ADDED
BOOST FROM DAYTIME HEATING.

TEMPERATURES IMPROVE BACK TOWARDS NORMAL THURSDAY AND FRIDAY AS
RIDGING ENDS PRECIPITATION CHANCES ACROSS THE CENTRAL GREAT LAKES.
BY SATURDAY THINGS IMPROVE EVEN MORE AS DAYTIME HIGHS GET TO AROUND
80 DEGREES.

&&

.MARINE...

THE PRIMARY MARINE HAZARD THROUGH THE WEEKEND WILL BE WIDESPREAD
THUNDERSTORMS EARLY THIS MORNING...ESPECIALLY FOR CENTRAL LAKE HURON
AND POINTS SOUTH INCLUDING LAKES SAINT CLAIR AND ERIE.
OTHERWISE...WINDS WILL REMAIN LIGHT TO MODERATE AND ARE EXPECTED TO
REMAIN WELL BELOW SMALL CRAFT ADVISORY CRITERIA. A COLD LOW PRESSURE
SYSTEM WILL MOVE INTO THE GREAT LAKES TUESDAY INTO WEDNESDAY. WEST
WINDS WILL GUST TO NEAR 20 KNOTS DURING THIS TIME. IN
ADDITION...WATERSPOUTS WILL BE LIKELY OVER AREAS OF WARMER WATER
BEGINNING MONDAY NIGHT. AREAS MOST AT RISK FOR WATERSPOUTS FROM
MONDAY NIGHT THROUGH WEDNESDAY NIGHT INCLUDE SOUTHERN HALF OF LAKE
HURON...LAKE SAINT CLAIR...AND THE MICHIGAN WATERS OF LAKE ERIE.

&&

.AVIATION...ISSUED 1149 PM EDT SAT JUL 12 2014

//DISCUSSION...

UPSTREAM RADAR AND LATEST MODEL GUIDANCE SUGGESTS SHOWERS AND STORMS
IMPACTING PTK/FNT/MBS BETWEEN 06Z AND 10Z AND METRO DETROIT BETWEEN
09Z AND 12Z. AN INFLUX OF MOIST AND UNSTABLE AIR INTO SRN MI OVER
THE NEXT 3 TO 6 HOURS AND UPPER SHORT WAVE ENERGY TRACKING IN FROM
WI/NRN IL WILL SET THE STAGE FOR FAIRLY WIDESPREAD COVERAGE OF
CONVECTION. BRIEF INTERVALS OF HEAVY RAIN AND PERIODIC REDUCTIONS IN
BOTH CEILINGS AND VISIBILITY WILL BE THE MAIN IMPACTS FROM THESE
STORMS. THE INSTABILITY AND DEEPER MOISTURE WILL QUICKLY EXIT TO THE
EAST AROUND DAYBREAK WITH THE PASSAGE OF A SURFACE TROUGH. THIS WILL
BRING AN ABRUPT END TO THE CONVECTION.

FOR DTW...GIVEN THE NE TO SW ORIENTATION OF THE INSTABILITY
AXIS...THE BETTER CHANCES FOR CONVECTION WILL ARRIVE IN METRO
DETROIT A LITTLE LATER THAN POINTS NORTH. THE MOST PROBABLE TIME
PERIOD STILL LOOKS TO BE BETWEEN 09Z AND 12Z.

//DTW THRESHOLD THREATS...

* THERE IS HIGH CONFIDENCE THAT THUNDERSTORMS WILL OCCUR OVERNIGHT
INTO EARLY SUN MORNING.

* THERE IS HIGH CONFIDENCE THAT CEILINGS WILL FALL BELOW 5000 FT
TONIGHT.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.

&&

$$

SHORT TERM...DRK
LONG TERM....KURIMSKI
MARINE.......KURIMSKI
AVIATION.....SC


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






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