Frost Advisory 2, NWS Detroit, MI

674 
WWUS73 KDTX 160141
NPWDTX

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
941 PM EDT THU SEP 15 2011

...AREAS OF FROST TO DEVELOP OVERNIGHT...

.CLEARING SKIES AND DIMINISHING WINDS WILL ALLOW TEMPERATURES
OVERNIGHT TO FALL INTO THE MIDDLE AND UPPER 30S. THIS WILL PROVIDE
FAVORABLE CONDITIONS FOR FROST FORMATION THROUGH THE PRE-DAWN HOURS.

MIZ047>049-053>055-060>063-161300-
/O.CON.KDTX.FR.Y.0002.110916T0800Z-110916T1300Z/
MIDLAND-BAY-HURON-SAGINAW-TUSCOLA-SANILAC-SHIAWASSEE-GENESEE-
LAPEER-ST. CLAIR-
INCLUDING THE CITIES OF...MIDLAND...BAY CITY...BAD AXE...
SAGINAW...CARO...SANDUSKY...OWOSSO...FLINT...LAPEER...PORT HURON
941 PM EDT THU SEP 15 2011

...FROST ADVISORY REMAINS IN EFFECT FROM 4 AM TO 9 AM EDT
FRIDAY...

A FROST ADVISORY REMAINS IN EFFECT FROM 4 AM TO 9 AM EDT FRIDAY. 

IMPACTS...

 * CROPS AND VEGETATION SUSCEPTIBLE TO FROST DAMAGE COULD SUFFER 
   IF LEFT UNPROTECTED. 

HAZARDOUS WEATHER...

 * TEMPERATURES WILL DROP INTO THE MIDDLE AND UPPER 30S ACROSS
   MANY LOCATIONS DURING THE PRE-DAWN HOURS. THIS WILL ALLOW FOR
   AREAS OF FROST DEVELOPMENT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

 * A FROST ADVISORY MEANS THAT FROST IS POSSIBLE. SENSITIVE
   OUTDOOR PLANTS MAY BE KILLED IF LEFT UNCOVERED.

$$

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
320 PM EDT THU SEP 15 2011

.SHORT TERM... TONIGHT

THE COLDEST 500MB TEMPERATURES SHOULD NOW BE EXITING TO OUR
EAST...BUT UPPER AIR IS STILL 1.5 STANDARD DEVIATIONS COLDER THAN
NORMAL FOR THIS TIME OF YEAR. THE WARMTH OF THE GREAT LAKES
CONTINUES TO RISE AGGRESSIVELY INTO THIS COLD AIR AND HAS SPREAD
INSTABILITY CU AND SHOWERS DOWNSTREAM OF THE MARINE AREAS TODAY.
WIDESPREAD CU IS BATTLED WITH A STRONG NEGATIVE OMEGA FIELD THAT
PROVIDES SUBSIDENCE AND KEEPS THE CLOUDS SCATTERED OR BROKEN IN
NATURE. THE 500MB TROUGH AXIS WILL BE WELL TO THE EAST TONIGHT AND
A 1027MB SFC HIGH WILL SETTLE OVER THE STATE. CURRENT GUSTY WINDS
WILL SETTLE TO LESS THAN 10MPH AT THE SURFACE AFTER 00Z AS THE
APPROACHING HIGH PRESSURE ELIMINATES PGF WINDS.

A BIG FORECAST CHALLENGE TONIGHT IS THE FROST THREAT AND HOW COLD
WILL OUR MINS GET TO. CIRRUS BLOWOFF FROM A SYSTEM IN THE CENTRAL
PLAINS WILL APPROACH LENAWEE AND WASHTENAW COUNTIES (AND LIKELY
FURTHER NORTH AND EAST) AND LIKELY PREVENT TEMPS FROM GETTING TO 36F
OR LOWER. FOR THE LOW TEMPS...WENT WITH A BLEND OF BIAS CORRECTED
GFS AND THE SREF...ALONG WITH PREVIOUS FORECAST. DROPPED THE USUAL
COOL SPOTS/RADIATORS A FEW DEGREES LOWER AS WELL. FROST ADVISORY HAS
BEEN ISSUED FOR COUNTIES AT AND NORTH OF I-69.

&&

.LONG TERM...FRIDAY THROUGH NEXT THURSDAY

A LARGE DOME OF HIGH PRESSURE WILL CENTER ITSELF OVER THE CENTRAL
GREAT LAKES ON FRIDAY. 850 MB TEMPERATURES WILL RISE A FEW DEGREES
TO THE LOWER SINGLE DIGITS ABOVE ZERO...ALLOWING HIGH TEMPERATURES
TO RISE A FEW DEGREES FROM TODAYS CHILLY VALUES. A CANOPY OF CIRRUS
CLOUDS WILL FILTER THE SUNSHINE DURING THE DAY...WITH MIXING HEIGHTS
TO 850 MB HIGHS THAT WILL TRANSLATE TO HIGH TEMPERATURES IN THE
LOWER 60S AWAY FROM THE THUMB.

THE HIGH WILL SLOWLY DRIFT EAST FRIDAY NIGHT AND SATURDAY...AS
HEIGHTS AND TEMPERATURES CONTINUE TO MODERATE. DESPITE THE
MODERATION...THE THINNING CIRRUS AND LIGHT WINDS UNDERNEATH THE
RIDGE OF HIGH PRESSURE MAY ONCE AGAIN LEAD TO FROST FORMATION ALONG
AND NORTH OF INTERSTATE 69 EARLY SATURDAY MORNING AS TEMPERATURES
DIP INTO THE MIDDLE TO UPPER 30S UNDER IDEAL RADIATIVE COOLING
CONDITIONS. TEMPERATURES WILL TREND UPWARD FROM THERE DURING THE
WEEKEND AS THE HIGH SLIDES OFF TO THE EAST...WINDS TURN TO A MORE
SOUTHERLY DIRECTION...AND 850 MB TEMPERATURES WARM INTO THE UPPER
SINGLE DIGITS ABOVE ZERO BY SUNDAY. HIGH TEMPERATURES SHOULD GET
WELL INTO THE 60S ON SATURDAY...WITH HIGHS AROUND 70 EXPECTED BY
SUNDAY UNDER ABUNDANT SUNSHINE AND INCREASING SOUTHERLY WINDS AHEAD
OF AN APPROACHING COLD FRONT.

A RATHER WEAK COLD FRONT WILL TRACK THROUGH THE CENTRAL GREAT LAKES
SUNDAY NIGHT AND MONDAY...BRINGING THE NEXT CHANCE FOR RAIN TO THE
REGION. THE BEST DYNAMICS WITH THIS FRONT WILL BE ACROSS THE
NORTHERN GREAT LAKES WHERE THE MID LEVEL TROUGH AND JET STREAM WILL
RESIDE...HOWEVER CONVERGENCE FROM THE SURFACE FRONT AND ASSISTANCE
FROM A SHORTWAVE ROUNDING THE TROUGH WILL BE ENOUGH TO KEEP THE
CHANCY POPS GOING FOR THIS PERIOD. WITH MLCAPE VALUES RISING TO A
FEW HUNDRED J/KG WITH PEAK HEATING ON MONDAY THUNDERSTORMS ARE A
POSSIBILITY WITH THIS FRONT. THIS FRONT WILL USHER IN AN ACTIVE
PERIOD DURING THE EXTENDED PORTION OF THE FORECAST AS SEVERAL
SHORTWAVES TRACK THROUGH THE FAST MOVING ZONAL FLOW THAT SETS UP
OVER THE GREAT LAKES THROUGH THE MIDDLE PORTION OF NEXT WEEK. WITH
THE LACK OF ANY STRONG SYSTEMS TO USHER IN PARTICULARLY COLD OR WARM
AIRMASSES...TEMPERATURES ARE EXPECTED TO HOVER AROUND CLIMATOLOGICAL
NORMALS DURING THIS PERIOD.

&&

.MARINE...

INSTABILITY REMAINS THE MAIN THREAT THIS EVENING AND TONIGHT AS THE
TEMPERATURE DIFFERENCE OVER THE LAKES AND AIR REMAINS QUITE HIGH
(NEAR 14K OVERNIGHT).  INSTABILITY CU AND SCATTERED SHOWERS WILL
REMAIN PRESENT OVER THE LAKES, AND WINDS WILL GUST TO 25-30KT FROM
THE NORTHWEST. LAPSE RATES ARE UP NEAR 5-7 K/KM THE NEXT 18 HOURS,
AND A NEW SZILAGYI WATERSPOUT INDEX (SWI) DEVELOPED BY OUR CANADIAN
COUNTERPARTS INDICATES EXTREMELY FAVOURABLE (+10) FROM 18-00Z...THEN
DROPPING OFF TO +3 AFTER 00Z WHICH IS STILL CONDUCIVE TO SPOUTS.

SMALL CRAFT ADVISORIES REMAIN IN EFFECT ONLY FOR WAVES TONIGHT AS
WIND GUSTS WILL RAPIDLY DECREASE AFTER SUNSET THIS EVENING. PRESSURE
GRADIENT WINDS WILL RELAX FOR FRIDAY AS HIGH PRESSURE CENTERS OVER
LOWER MICHIGAN.

&&

.AVIATION...ISSUED 131 PM EDT THU SEP 15 2011

//DISCUSSION...

A WIDESPREAD CU FIELD HAS DEVELOPED ACROSS THE TAF SITES TODAY
VARYING FROM 4-5 KFT. THESE SMALL TUFTS OF CLOUDS WILL GROW SOME
THIS AFTERNOON WITH THE INCREASE OF SFC HEATING GROWING INTO VERY
COLD AIR ALOFT. LAPSE RATES ARE QUITE STEEP AND EXPECTING THE CU TO
BECOME BROKEN SHORTLY AFTER TAF ISSUANCE. NO MVFR IS EXPECTED WITH
CLOUD BASES LIKELY AT 5 KFT OR HIGHER. ANY THREAT OF A SHOWER WILL
BE FURTHEST NORTH NEAR MBS AND EVEN THAT CHANCE IS TOO LOW TO
MENTION IN TAF.

CIRRUS BLOWOFF SEEN ON IR IMAGERY IN THE CENTRAL PLAINS WILL ENTER
LATE TONIGHT THROUGH DAYTIME FRIDAY...OTHERWISE NO CIG/VIS WORRIES
FOR THE AVIATION INTERESTS. WIND SPEEDS CONTINUE TO GUST NEAR 20KT
THROUGH THE AFTERNOON FROM THE NNW. LACK OF MIXING AFTER 00Z WILL
END THE GUSTS AND HIGH PRESSURE CENTERING OVER LOWER MI WILL KEEP
JUST LIGHT WINDS PRESENT.

//DTW THRESHOLD THREATS...

* NONE

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...FROST ADVISORY...MIZ047-MIZ048-MIZ049-MIZ053-MIZ054-MIZ055-MIZ060-
     MIZ061-MIZ062-MIZ063...FROM 4 AM FRIDAY TO 9 AM FRIDAY.

LAKE HURON...
     SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
     HURON INCLUDING OUTER SAGINAW BAY...UNTIL 8 AM FRIDAY.

     FROST ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO HARBOR
     BEACH...FROM 4 AM FRIDAY TO 9 AM FRIDAY.

LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.

&&

SHORT TERM...MM
LONG TERM....KURIMSKI
MARINE.......MM
AVIATION.....MM

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
730 AM EDT THU SEP 15 2011

MIZ047>049-053>055-060>063-068>070-075-076-082-083-161130-
MIDLAND-BAY-HURON-SAGINAW-TUSCOLA-SANILAC-SHIAWASSEE-GENESEE-LAPEER-
ST. CLAIR-LIVINGSTON-OAKLAND-MACOMB-WASHTENAW-WAYNE-LENAWEE-MONROE-
730 AM EDT THU SEP 15 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST MICHIGAN.

.DAY ONE...TODAY AND TONIGHT

FROST WILL BE POSSIBLE IN MOST RURAL LOCATIONS TONIGHT AS AN
UNSEASONABLY COOL CANADIAN HIGH PRESSURE SETTLES OVER THE AREA.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THERE IS A CHANCE FOR THUNDERSTORMS MONDAY THROUGH WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT.

LHZ361>363-421-441>443-462>464-161130-
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-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-
730 AM EDT THU SEP 15 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF LAKE HURON.

.DAY ONE...TODAY AND TONIGHT

SHOWERS DEVELOPING OVER LAKE HURON TODAY WILL BE CAPABLE OF
PRODUCING WATERSPOUTS AND ISOLATED THUNDERSTORMS.

SMALL CRAFT ADVISORIES ARE IN EFFECT FOR OUTER SAGINAW BAY AND THE
NEARSHORE WATERS OF SOUTHERN LAKE HURON. PLEASE REFER TO THE LATEST
MARINE FORECAST FOR DETAILS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT.

LCZ422-423-460-LEZ444-LHZ422-161130-
ST. CLAIR RIVER-DETROIT RIVER-LAKE ST. CLAIR-
MICHIGAN WATERS OF LAKE ERIE FROM DETROIT RIVER TO NORTH CAPE MI-
INNER SAGINAW BAY SW OF POINT AU GRES TO BAY PORT MI-
730 AM EDT THU SEP 15 2011

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

.DAY ONE...TODAY AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THERE IS A CHANCE FOR THUNDERSTORMS MONDAY THROUGH WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT.

BT

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