HAMweather.com Area Forecast Discussion for County Warning Area APX

Thu, 16 Feb 2012 13:23:53 GMT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
627 AM EST THU FEB 16 2012

.UPDATE...
ISSUED AT 626 AM EST THU FEB 16 2012

CAN SAFELY ACCELERATE EXITING SNOW FROM NORTHERN LOWER MI THIS
MORNING. WILL ALSO NEED TO BE MORE AGGRESSIVE WITH -DZ/-RA BEHIND
THE MAIN SNOW AREA...WHICH WILL LAST UNTIL WEST WINDS KICK IN
TOWARD MIDDAY AND BRING SOMEWHAT DRIER AIR IN FROM WI (NOTE BREAKS
IN CLOUDS BACK IN EASTERN WI). EASTERN UPPER MI IS LARGELY FINE.
NOTE THAT 06Z NAM BRINGS PRECIP A BIT FURTHER SOUTH THIS AFTERNOON
INTO PARTS OF NORTHERN LOWER.

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 356 AM EST THU FEB 16 2012

LOW PRESSURE IS BARELY DISCERNIBLE JUST WEST OF LAFAYETTE IN...WITH
ADDITIONAL LOW PRESSURE IN FAR NORTHERN ONTARIO. OUT AHEAD OF THE
THESE FEATURES...SOUTHERLY LOW LEVEL WINDS WERE ADVECTING
WARMER/MORE MOIST AIR NORTHWARD. SHOWERS OF MIXED PRECIP STARTED
DEVELOPING IN SOUTHERN AREAS JUST BEFORE MIDNIGHT. SNOW...SLEET...
RAIN (NEAR COASTS) AND FREEZING RAIN (INLAND)...WERE ALL
POSSIBILITIES AT THE START OF EVENT. BUT WE HAVE ALREADY SETTLED
INTO MOSTLY (IF NOT ALL) SNOW...WITH SAGINAW BAY AND MBL/FRANKFORT
THE MAIN QUESTION MARKS. PRECIP TRENDS ARE THE MAIN CONCERN
TODAY.

A HAT-TIP TO YESTERDAYS ECMWF...AS THE SURFACE LOW WILL CROSS LOWER 
MI THIS MORNING IN AN EXTREMELY DISHEVELED STATE. ONLY A N-S 
ORIENTED TROF OF LOW PRESSURE WILL MOVE INTO EASTERN INDIANA/WESTERN 
LOWER MI/CENTRAL UPPER MI BY 12Z. THIS IS OCCURRING AS THE SOUTHERN 
STREAM SHORTWAVE CONTINUES TO DEAMPLIFY...AND JUST BEFORE THE LEAD 
NORTHERN STREAM WAVE MAKES AN IMPACT. WITH THAT SHARP NORTHERN 
STREAM SHORTWAVE REACHING NORTHERN WI/WESTERN UPPER MI BY 18Z...THE 
SURFACE LOW WILL REORGANIZE SOON AFTER 12Z. EXPECT A 1012MB LOW OVER 
CENTRAL LAKE HURON BY 18Z...AND 1010MB NORTH OF GEORGIAN BAY BY 00Z. 
NOT SURPRISINGLY...THERE/S ALSO NO LONGER A SIGN OF A CLOSED 700MB 
CIRCULATION. THAT LIMITS THE AMOUNT OF MID-LEVEL DEFORMATION WE/LL 
SEE TODAY.

WITH THIS IN MIND...AM GENERALLY GOING TO BE REDUCING PRECIP TOTALS 
TODAY. THIS IS ESPECIALLY THE CASE IN NW LOWER...WHERE MODEL AND 
RADAR TRENDS SUGGEST LITTLE IF ANY PRECIP WEST OF A MESICK-CVX LINE 
AFTER 12Z/7AM. THE SOUTHEAST (ALONG AND S OF AN HTL-APN LINE)
WILL STILL DO ALL RIGHT THIS MORNING...MAINLY EARLY. A TOP END OF
AROUND A QUARTER-INCH OF QPF IS REASONABLE. BUT...THAT WILL NOT
FALL AS ALL SNOW IN ALL SPOTS. THOUGH THE INITIAL WARM NOSE AT
850-900MB WAS NOT BE LONG FOR THIS WORLD THANKS TO EVAP
COOLING...NAM SOUNDINGS SUGGEST ANOTHER WEAKISH WARM NOSE
ADVECTING NORTHWARD INTO THE FAR SE... CENTERED ON 09Z...WITH
925-950MB TEMPS OF 1C. WITH THAT WARM NOSE GONE AT 12Z...IT/S
STILL PRIMARILY A SNOW EVENT...BUT PL WILL AND RA/FZRA COULD MIX IN
EARLY ON. THUS WILL TOP OUT SNOW ACCUMS AT 2 INCHES IN THE
SE...WITH LESS ELSEWHERE.

BY 18Z/1PM...PRECIP ASSOCIATED WITH THE DEPARTING SURFACE LOW SHOULD 
ALREADY PRETTY MUCH BE GONE. WILL ALLOW FOR SOME TRAILING DRIZZLE
IN SOME SPOTS (MAINLY NW LOWER) BEFORE ENDING THINGS ENTIRELY. SOME
PEEKS OF SUNSHINE ARE CERTAINLY POSSIBLE IN MUCH OF NORTHERN LOWER
MI IN THE AFTERNOON...THOUGH STEEP LOW-LEVEL LAPSE RATES AND A
MOIST BL WILL TEND TO FILL IN BREAKS RATHER QUICKLY. MAIN PRECIP
FOCUS SHIFTS NORTH TO EASTERN UPPER MI...WHERE SHARP DPVA FORCING
ARRIVES AS THE NORTHERN STREAM WAVE MOVES IN AND TAKES ON A
NEGATIVE TILT. A DEEP/MOIST UNSTABLE LAYER UP THRU 700MB WILL
SUPPORT SHSN DEVELOPMENT IN NORTHERN AREAS DURING THE AFTERNOON.
LOCAL ACCUMS OF AN INCH...WILL BE POSSIBLE.

A GOOD CHUNK OF NORTHERN LOWER WILL TAKE A RUN AT 40F THIS 
AFTERNOON...AFTER PRECIP EXITS. IN EASTERN UPPER MI...MID 30S WILL 
BE MORE COMMON.

TONIGHT...LOW PRESSURE CONTINUES TO COALESCE AND DEEPEN TO OUR NE. W 
TO NW LOW LEVEL WINDS IN THE WAKE OF THE LOW WILL CONTINUE TO BRING 
SLIGHTLY COOLER AIR INTO THE REGION. BUT 850MB TEMPS WILL ONLY LOWER 
FROM -8C TO -10C...SO DELTA T/S TOP OUT AROUND 14 BY MORNING...WHICH 
ISN/T TERRIBLY IMPRESSIVE. MOISTURE WILL BE MOST PREVALENT NORTH OF 
M-72...AND ESPECIALLY ON SUPERIOR (WHERE 850-700MB RH WILL EXCEED 85 
PERCENT). WITH A SECONDARY COLD FRONT LINGERING ON SUPERIOR...THE 
LOW LEVEL FLOW WILL BE CONSIDERABLY MORE CYCLONIC UP THERE. AFTER A 
RELATIVE LULL TO START THE EVENING (WITH A QUICK SHOT OF SUBSIDENCE 
BEHIND THE INITIAL NORTHERN STREAM SHORTWAVE)...WOULD EXPECT SNOW 
SHOWERS TO BECOME LIKELY ALONG/N OF M-28 IN CHIPPEWA CO. LOCAL 
ACCUMS OF AN INCH OR SO CAN BE EXPECTED. IN NORTHERN LOWER...DON/T 
REALLY THINK LIKELY POPS ARE JUSTIFIED IN A DRIER AIRMASS AND 
FLATTER LOW-LEVEL FLOW. WILL KEEP POPS CHANCY/SCT...AND MOSTLY NORTH 
OF M-72...WITH LITTLE IN THE WAY OF ACCUMS. OUTSIDE OF LAKE EFFECT 
AREAS...WE/LL SEE PARTLY TO MOSTLY CLOUDY SKIES...WITH THE GREATEST 
CLEARING IN THE SOUTH. MIN TEMPS WILL RANGE THRU THE 20S.

FRIDAY...NEXT IN A SERIES OF DIGGING NORTHERN STREAM SHORTWAVES WILL 
ONLY REACH FAR WESTERN ONTARIO BY THE END OF THE DAY. THUS...IT 
WON/T POSE AN ISSUE FOR US UNTIL LATER. HOWEVER...WE WILL STILL SEE 
SOME FGEN PROCESSES UNDERWAY HERE...AS 850MB TEMPS LOWER TO -12C ON 
EASTERN UPPER MI...WHILE WARMING TO -8C IN THE SOUTH. 
CORRESPONDINGLY...MID-LEVEL MOISTENING TAKES PLACE IN NORTHERN 
LOWER...WITH 850-700MB RH LEVELS RISE TO 80-90 PERCENT DURING THE 
AFTERNOON. WITH INSTABILITY SLOWLY INCREASING ON SUPERIOR...AND A 
WNW/NW FETCH CONTINUING...WILL MAINTAIN LIKELY POPS IN WESTERN/ 
CENTRAL CHIPPEWA...AND 1-2 INCH LOCAL ACCUMS. SIMILARLY...SCT/CHANCY 
LAKE EFFECT CONTINUES NORTH OF M-72...AND WILL EXPAND POPS A LITTLE 
SOUTHWARD IN NW LOWER GIVEN THE FGEN/MOISTENING SIGNALS MENTIONED 
ABOVE. NO SIGNIFICANT ACCUMS IN NW LOWER. MAX TEMPS LOW TO MID 30S.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 356 AM EST THU FEB 16 2012

FRIDAY NIGHT AND SATURDAY...THE WEAK SYSTEM THAT EXITED THE GREAT 
LAKES EARLY FRIDAY...WILL CONTINUE TO LIFT NORTH ACROSS QUEBEC INTO
SATURDAY...WHILE A SECOND FEATURE OVER THE CENTRAL PLAINS LIFTS INTO 
THE OHIO VALLEY. AT UPPER LEVELS...A SHARPENING 500MB TROUGH WILL 
BUILD INTO THE WRN LAKES EARLY SATURDAY...BEFORE QUICKLY EXITING 
EAST SATURDAY NIGHT. THE BEST SYNOPTIC MSTR AND LIFT WILL BE 
CENTERED OVER THE STATE FRIDAY NIGHT INTO SATURDAY AFTERNOON...
BEFORE QUICKLY EXITING EAST OF LAKE HURON BY THE EVENING. LAKE 
EFFECTS WILL BECOME AN INFLUENCE ACROSS NRN MI...AS THE SFC AND 
UPPER LEVEL FEATURES EXIT THE REGION. 850MB TEMPS WILL BE 
MARGINAL...ONLY FALLING TO AROUND -12/-13C WHILE VARIABLE 925-850MB 
WINDS TURN MORE NORTHERLY THROUGH THE AFTN. MODEL SOUNDINGS SHOW 
WEAK INVERSION HEIGHTS TO AROUND 6K FT. LAKE PROCESSES WILL LINGER 
OVER THE WRN LAKES INTO EARLY SUNDAY...BEFORE 850MB TEMPS INCREASE 
TO WARMER THAN -11C OVER THE NRN LAKES. WILL KEEP MENTION OF SNOW 
SHOWERS ACROSS THE ENTIRE CWA FRIDAY NIGHT AND SATURDAY...IN RESPONSE 
TO SYNOPTIC SNOWS AND LAKE EFFECTS. 

SUNDAY AND MONDAY...A LARGE AREA OF HIGH PRESSURE OVER THE PLAINS 
AND UPPER MIDWEST...WILL BUILD INTO THE WRN LAKES SUNDAY BEFORE 
BECOMING CENTERED OVER THE STATE MONDAY. AT UPPER LEVELS...NEARLY 
ZONAL FLOW SUNDAY WILL TRANSITION TO INCREASING 500MB HEIGHTS...
WHILE AN UPPER RIDGE BECOMES CENTERED OVER THE STATE MONDAY. THIS 
PATTERN WILL GENERATE MAINLY A DRY AND MILD FORECAST ACROSS NRN 
MICHIGAN THROUGH MONDAY. HIGH TEMPS SUNDAY WILL BE IN THE UPPER 20S 
WITH 850MB TEMPS AROUND -10C...WARMING TO AROUND 35 DEGREES MONDAY 
AS 850MB TEMPS WARM TO AROUND -6C. 

PRECIPITATION WILL BUILD BACK INTO THE REGION TUESDAY AND 
WEDNESDAY...AS A SYSTEM ORGANIZING OVER THE SRN PLAINS...LIFTS INTO 
THE UPPER MIDWEST. WARMING MID LEVELS IN ADVANCE OF THE APPROACHING 
SYSTEM...COULD GENERATE SOME PCPN TYPE QUESTIONS TUESDAY AND INTO 
WEDNESDAY. EXPECT AFTERNOON HIGH TEMPS INTO MID WEEK TO BE ABOVE 
SEASONAL LEVELS IN THE LOW TO MID 30S...AS 850MB TEMPS WARM TO 
BETWEEN -1C AND -3C. 
   
SWR

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 626 AM EST THU FEB 16 2012

SNOW WILL BE EXITING NE LOWER MI OVER THE NEXT 2-3 HOURS. A WAVE
OF -DZ OR EVEN -RA WITH IFR CONDITIONS IS TRAILING THE SNOW
AREA...AS THE LOW LEVEL REMAIN MOIST WHILE THE MID LEVELS DRY.
THAT WILL LAST UNTIL ABOUT LATE MORNING...WHEN INCREASING WEST
WINDS WILL START THE DRYING PROCESS. CIGS WILL REMAIN MVFR THRU
THIS AFTERNOON AND INTO TONIGHT...THANKS TO LAKE-INDUCED CLOUD
COVER. 

.MARINE...
ISSUED AT 356 AM EST THU FEB 16 2012

WEAK WINDS EARLY TODAY...AS A TROF OF LOW PRESSURE CROSSES LOWER
MI FROM WEST TO EAST. LOW PRESSURE WILL BEGIN STRENGTHENING JUST
TO OUR EAST THIS AFTERNOON...AND CONTINUE INTO EARLY FRIDAY. W TO
NW WINDS WILL INCREASE AS THIS HAPPENS...AND MOST WATERS WILL BE
RATHER CHOPPY BY TONIGHT. RATHER MARGINAL AS TO WHETHER SMALL
CRAFT ADVISORY CONDITIONS WILL BE REACHED...THE NW LOWER MI COAST
AND NE LOWER NEAR PRESQUE ISLE LT HAVE THE BEST CHANCE. NO
ADVISORIES WILL BE ISSUED AT THIS TIME.

.APX WATCHES/WARNINGS/ADVISORIES...
NONE.