557 FXUS63 KAPX 231127 AFDAPX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 625 AM EST SUN NOV 23 2008 .SYNOPSIS.../ISSUED AT 350 AM/ HIGH PRESSURE OVER OHIO AND LAKE HURON WILL CONTINUE TO MOVE AWAY FROM THE REGION. A PAIR OF UPPER LEVEL DISTURBANCES WILL COMBINE TO CARVE OUT A SIGNIFICANT LOW PRESSURE SYSTEM TO OUR SE ON MONDAY AND MONDAY NIGHT. THIS SYSTEM WILL BRING ACCUMULATING SNOW TO MUCH OF NORTHERN MI. && .SHORT TERM.../ISSUED AT 350 AM/...TODAY RELATIVELY TRANQUIL. WEAKENING SHORTWAVE WILL PASS NORTH AND EAST OF THE SOO. A FEW FLURRIES REPORTED NORTH OF LAKE SUPERIOR EARLIER IN THE NIGHT. THOUGH THE BEST SUPPORT STAYS TO OUR NORTH...THERE IS STILL THE MATTER OF ENHANCED 800-700MB MOISTURE INTERACTING WITH LINGERING LAKE INSTABILITY (850MB TEMPS -6 TO -7C...DELTA T/S 13-14). GFS/NAM BOTH MANAGES TO SQUEEZE OUT A LITTLE PRECIP IN EASTERN UPPER TODAY...AND WILL KEEP SOMETHING IN THRU THE DAY. FLURRIES SHOULD SUFFICE FOR THE MORNING. BY AFTERNOON MOISTURE ONLY EXTENDS UP TO -8C...AND WILL ADD DZ/FZDZ. SUB-800MB AIRMASS NOT PROGGED TO BE AS MOIST SOUTH OF THE BRIDGE. WILL NEED TO MONITOR THE HIGH TERRAIN FROM CAD TO GLR THIS AFTERNOON...BUT FOR NOW WILL LEAVE DZ OUT. GENERALLY ON THE CLOUDY SIDE...THOUGH THE SE AND FAR SOUTH WILL SEE SOME SUNSHINE...ESPECIALLY THIS MORNING. MAX TEMPS IN THE 30S... PRACTICALLY A HEAT WAVE. JZ && .LONG TERM.../ISSUED AT 350 AM/...TONIGHT AND BEYOND NORTHERN STREAM UPPER LOW WILL DIVE SOUTH AND EAST FROM FAR WESTERN ONTARIO...ENDING UP OVER THE EASTERN LAKES BY TUESDAY. A SOUTHERN STREAM SHORTWAVE MOVING THRU THE OHIO VALLEY WILL PHASE WITH THE LOW...GIVING IT SOME EXTRA KICK. THE EXTENDED PRECIP EVENT EXPECTED FROM THIS SYSTEM IS THE CLEAR MAIN CHALLENGE. MODELS...THE NAM IS A BIT SLOWER TO DIVE THE UPPER LOW THRU THE WESTERN LAKES...AND IS NOT AS DEEP WITH THE SYSTEM ONCE ITS TO OUR EAST ON TUESDAY. THE NAM IS A CONSIDERABLE OUTLIER IN OTHER RESPECTS...ESPECIALLY OUT WEST (PER HPC DISCUSSION)...AND THE OPERATIONAL GFS OFFERS A BETTER AND MORE CONSISTENT SOLUTION. TONIGHT...SHORTWAVE RIDGING ALOFT WILL MOVE DOWNSTREAM OF NORTHERN MI. DEEP WARM/MOIST ADVECTION WILL INCREASE TONIGHT...ESPECIALLY LATE...IN ADVANCE OF A SHORTWAVE NEARING EASTERN IOWA AND AN UPPER LOW NEARING ONTARIO/MANITOBA BORDER. THIS NARROW MOIST BAND WILL DEVELOP ALONG AND JUST OF AHEAD A PAIR OF SURFACE LOWS...THE STRONGER ONE ON SUPERIOR...THE SOON-TO-BE-STRONGER ONE OVER THE SOUTH END OF LAKE MI. WILL REMOVE PRECIP FOR THE EVENING HOURS...AND HAVE A CHANCE FOR SNOW EVERYWHERE BUT THE SE ZONES...WITH THE HIGHEST POPS WEST AND NORTH. WILL ALSO ALLOW FOR A RAIN/SNOW MIX NEAR MBL AND FRANKFORT. THANKS TO WARM ADVECTION AND MARINE INFLUENCES...THE SURFACE-BASED MELTING LAYER INCREASES TO NEAR 1K FEET HERE. CLOUDY AND RELATIVELY MILD...WITH MINS IN THE 20S TO NEAR 30. MONDAY...SOUTHERN STREAM WAVE NEARS CINCY...UPPER LOW DROPS INTO WI...AND A SINGLE SURFACE LOW CONSOLIDATES AND DEEPENS AS IT NEAR PT HURON. DEEP UPWARD VERTICAL MOTION DEVELOPS DURING THE MORNING...IN RESPONSE TO UPPER JET FORCING AND RAPIDLY FALLING HEIGHTS. 700-600MB Q-VECTOR CONVERGENCE IS MODERATE BUT UNRELENTING ACROSS NORTHERN LOWER MI. EASTERN UPPER MI...FURTHER AWAY FROM THE MORE CONVENTIONAL SYNOPTIC SUPPORT...WILL BENEFIT FROM A 700-600MB DEFORMATION MAXIMA. SO PRECIP WILL QUICKLY BECOME WIDESPREAD. THIS WILL BE MOSTLY SNOW. HOWEVER...WILL MENTION A MIX NEAR LAKE MI...WITH WARMER WATER TEMPS AND SURFACE-BASED MELTING LAYER NEAR 1K FT IN GFS SOUNDINGS. SURFACE TEMPS WILL BE FAIRLY WARM...NEAR OR SLIGHTLY ABOVE FREEZING... ESPECIALLY NEAR THE GREAT LAKES. THIS WILL KEEP SNOW/LIQUID RATIOS ON THE LOW SIDE. SNOWFALL AMOUNTS LOOK TO BE 2 TO 3 INCHES IN NORTHERN LOWER...WITH THE HIGHEST AMOUNTS INLAND WITH LESS MELTING. 1 TO 2 INCHES NORTH OF THE BRIDGE. 850MB TEMPS -6 TO -7C MIGHT BRING SOME LAKE ENHANCEMENT INTO PLACES LIKE LEELANAU COUNTY AS NORTHERLY LOW LEVEL FLOW DEVELOPS...BUT AGAIN THE SURFACE LAYER HERE WILL BE WARMER. MAX TEMPS IN THE 30S. MONDAY NIGHT/TUESDAY...UPPER LOW MOVES TO LAKE ERIE MON NIGHT...AND THE NY/PA BORDER TUESDAY. SURFACE LOW HOVERS OVER FAR SOUTHERN ONTARIO THRU MONDAY NIGHT...BEFORE ENERGY TRANSFERS TO A TRIPLE POINT LOW OVER NY STATE. SAID LOW THEN ROTATES BACK OVER TOP OF LAKE ONTARIO. WE REMAIN UNDER DEEP MOISTURE MONDAY NIGHT...BUT THAT STARTS TO STRIP AWAY DURING THE DAY TUESDAY AS A DOMINANT DEFORMATION/WRAPAROUND BAND EMERGES JUST EAST OF LAKE HURON. WIDESPREAD SNOW WILL CONTINUE IN NORTHERN LOWER MI MONDAY NIGHT...WITH ANOTHER 1-3 INCHES POSSIBLE...HIGHEST NEAR AND EAST OF I-75. WILL CONTINUE WITH JUST LIKELY POPS IN EASTERN UPPER MI...AS THEY TRY TO EMERGE FROM THE DEEP MOISTURE JUST TO THEIR EAST. AROUND 1 INCH OF SNOW UP THERE. LOWS NEAR 30. SYNOPTIC SNOW SHOULD GRADUALLY FIZZLE OUT ON TUESDAY. HOWEVER... SOMEWHAT COLDER AIR (850MB TEMPS -8 TO -9C) AND LINGERING MOISTURE (850-700MB RH LEVELS ABOVE 70 PERCENT) WILL PROBABLY KEEP SNOW GOING IN FAVORED NORTH FLOW AREAS. WILL BOOST POPS TO LIKELY NEAR ROGERS CITY/APN...AND IN TVC AND POINTS WEST. HIGHS LOW TO MID 30S. REST OF THE FORECAST...A WESTWARD WOBBLE COULD RETURN LIGHT SYNOPTIC SNOW TO THE REGION FOR THE BUSY TRAVEL DAY WED...WITH SOME ENHANCEMENT IN N/NNW FLOW AREAS. FOR NOW...WILL JUST ADD A CHANCE OF SNOW SHOWERS TO THE EASTERN ZONES WED...BUT THIS MAY NEED TO BE EXPANDED IN LATER FORECASTS. STILL COOLISH THRU THE PERIOD...BUT WARM AIR INTRUSION SEEN FROM THE NORTH IN YESTERDAYS RUNS IS NO LONGER PRESENT. SIGH. JZ && .MARINE.../ISSUED AT 350 AM/ QUIET PERIOD ON THE WATERS IS SHORT LIVED. INCREASING SW FLOW AND THE LONG FETCH ON LAKE MI WILL PRODUCE SMALL CRAFT CONDITIONS TODAY AND TONIGHT ON LAKE MI...AS WELL AS ON THE UPPER MI COASTLINE OF HURON. AS LOW PRESSURE STRENGTHENS TO OUR EAST MONDAY NIGHT AND TUESDAY...GALES ARE POSSIBLE ON PARTS OF LAKE MI. JZ && .AVIATION.../ISSUED AT 625 AM/...VALID FOR 12Z TAFS MOISTURE OFF OF LAKE MI IS CONTRIBUTING TO A WIDE RANGE OF CIGS ACROSS NORTHERN LOWER MI...FROM 2K TO 6K FEET...WITH SOME BREAK AS WELL. CIGS WILL CONTINUE TO BE VARIABLE FOR THE UPCOMING DAY AND EVENING...AS MOISTURE FROM THE LAKES BATTLES WITH OTHERWISE DRY LOW LEVEL AIR. LATE TONIGHT...UPPER DISTURBANCES WILL APPROACH FROM THE WEST AND NW. LIGHT SNOW MAY BREAK OUT VERY LATE NEAR PLN/TVC...WITH WORSENING CONDITIONS EXPECTED AT ALL TAF SITES AFTER 12Z. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...SMALL CRAFT ADVISORY UNTIL 5 AM EST MONDAY FOR LMZ341-342- 344>346. GALE WATCH FROM MONDAY EVENING THROUGH TUESDAY EVENING FOR LMZ344>346. LH...SMALL CRAFT ADVISORY UNTIL 5 AM EST MONDAY FOR LHZ346. LS...NONE. && $$