FXUS63 KMQT 201752 AAB
AFDMQT
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MARQUETTE MI
1245 PM EST MON JAN 19 2009
UPDATED FOR 18Z AVIATION DISCUSSION
.SYNOPSIS...
08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS STILL SHOWS A 
HIGH AMPLITUDE PATTERN ACROSS NORTH AMERICA...WITH STRONG RIDGING 
OVER THE WESTERN U.S. INTO SW CANADA...AND TROUGHING OVER SE CANADA 
INTO THE EASTERN U.S.. UPPER MI CONTINUES TO BE INFLUENCED BY THE 
TROUGH...AND AS SUCH 850MB TEMPS REMAIN ON THE COOL SIDE...AROUND 
-15C PER 00Z RAOBS. SINCE THE AIRMASS REMAINS COLD...LAKE EFFECT 
SNOW SHOWERS ALSO CONTINUE. ALL ACCUMULATIONS ARE VERY FLUFFY...WITH 
SNOW TO WATER RATIOS OF 50 TO 1 OR SO. THIS IS DUE TO THE LAKE 
EFFECT CLOUDS BEING COMPLETELY CONTAINED WITHIN THE DENDRITIC SNOW 
GROWTH ZONE (DGZ)...AS SHOWN BY A 02Z TAMDAR SOUNDING FROM SAW. 
BASICALLY...WE HAVE BEEN GETTING A LOT OF BANG FOR OUR BUCK...WITH A 
LOT OF SNOW TURNING UP FOR LITTLE QPF. THIS CONTINUES NOW...WITH 
SNOWFALL AMOUNTS FROM 7 PM TO 330 AM AT THE OFFICE OF 5.3 INCHES.  
POSITION OF THE LAKE EFFECT THE PAST FEW DAYS HAS BEEN FOCUSED A LOT 
BY MESOSCALE FACTORS...SUCH AS LAND BREEZES AND TROUGHS EXTENDING 
BACK FROM WEAK LOW PRESSURE IN MAINE. EVEN THE ICE THAT IS PRESENT 
ON LAKE SUPERIOR (NEAR THE APOSTLES AND COVERING A LOT OF OUR LSZ265 
ZONE) MAY BE HELPING A BIT AS A CONVERGENCE FOCUSING MECHANISM. 
CURRENTLY...ONE OF THOSE TROUGHS EXTENDS FROM SOUTHERN LAKE HURON NW 
ACROSS ESC AND TO ONTONAGON. NORTH OF THIS TROUGH...A SFC RIDGE IS 
NOTED ALONG THE NORTH SHORE OF LAKE SUPERIOR. BETWEEN THESE TWO 
FEATURES...A NORTH TO NE FLOW HAS HELPED TO CONFINE THE LAKE EFFECT 
SNOW TO MARQUETTE/WRN ALGER COUNTIES. CONVERGENCE ALONG THE TROUGH 
IS ALSO BRINGING LAKE EFFECT INTO WRN GOGEBIC/ONTONAGON COUNTIES. 
AREAS THAT ARE STAYING QUIET IN THE U.P. ARE CRYSTAL FALLS...ISQ AND 
ERY...WITH MOSTLY CLEAR SKIES. TEMPS HAVE FALLEN TO AROUND ZERO IN 
ALL THREE PLACES...WITH TYPICAL COLD SPOTS NEAR THEM BELOW ZERO. 
FARTHER UP TO OUR NW...A SHRTWV IS MOVING SE DOWN THE TOP OF THE 
RIDGE TO NEAR CHURCHILL MANITOBA. 00Z RAOB AT CYQD HAD AN 850MB TEMP 
OF 3C...AND SOME OF THIS WARM AIR WILL LIKELY GET PULLED EASTWARD AS 
THIS SHRTWV DROPS SOUTH INTO THE TROUGH. 
&&
.DISCUSSION...
MAIN HIGHLIGHT TO THE FORECAST IS THE TEMPORARY END OF THE LAKE 
EFFECT THIS AFTERNOON.
TODAY...SHRTWV APPROACHING CHURCHILL MANITOBA WILL CONTINUE ITS 
DESCENT SOUTHWARD...REACHING FAR NORTHERN ONTARIO BY 00Z. BECAUSE 
THIS SHRTWV IS DROPPING SOUTH...THE HIGH PRESSURE RIDGE ALONG THE 
NORTH SHORE OF LAKE SUPERIOR WILL ALSO HAVE TO BE FORCED SOUTHWARD. 
IN FACT...BY 00Z IT SHOULD BE SITUATED DOWN IN SRN LOWER MI. 
THEREFORE WINDS ARE EXPECTED TO BACK THROUGH THE DAY...ALLOWING WARM 
ADVECTION TO TAKE HOLD. MUCH OF THE WARM TAKES PLACE ABOVE 950MB AND 
PEAKS AT 850MB...WHERE SOUNDINGS FOR CMX SHOW A 24 HOUR RISE OF 12C 
BY 00Z WITH A READING OF -4C. THIS WARMING CAUSES INVERSIONS TO 
CRASH SUBSTANTIALLY THROUGH THE DAY...SO LAKE EFFECT SHOULD 
COMPLETELY SHUT OFF OVER WESTERN SUPERIOR...MAYBE AS EARLY AS 18Z. 
WARMING TAKES LONGER TO CROSS EASTERN SUPERIOR...SO LAKE EFFECT 
PROBABLY DOES NOT SHUT OFF UNTIL 21Z OR 00Z. HOWEVER...LAKE EFFECT 
PCPN OVER LAND WILL BE DONE BY 18Z DUE TO WINDS BACKING TO THE WEST. 
SINCE THE LAKE EFFECT IS MOVING AND DIMINISHING THROUGH TIME...LOOK 
FOR ADDITIONAL ACCUMULATIONS TO BE LIGHT...PERHAPS PEAKING UP TO 
ANOTHER 3 INCHES IN ALGER COUNTY. GOING END TIMES OF HEADLINES SEEM 
REASONABLE. OUTSIDE OF THE LAKE EFFECT...DRY CONDITIONS WILL OCCUR 
WITH SUBSIDENCE AND DRY AIR. ALTHOUGH WE ARE WARMING ALOFT...THE 
IMPACT AT THE SFC IS EXPECTED TO BE LESS DUE TO THE VERY LOW SUN 
ANGLE THIS TIME OF YEAR. STAYED TOWARD THE LOW END OF GUIDANCE FOR 
HIGHS DUE TO THE STRONG SUBSIDENCE SEEN ON SOUNDINGS...AND EXPECTED 
INCREASE IN HIGH CLOUDS DURING THE AFTN.
TONIGHT...UPPER RIDGE OVER THE WESTERN U.S. IS PROGGED TO BEGIN 
FLATTENING SOMEWHAT AS A SHRTWV TROUGH IN THE GULF OF ALASKA MOVES 
INLAND. THIS FLATTENING OF THE UPPER RIDGE WILL HELP TO KEEP THE 
SHRTWV THAT IS APPROACHING CHURCHILL WELL OFF TO OUR EAST...PROGGED 
TO REACH THE ONTARIO/QUEBEC LINE BY 12Z WED. HOWEVER...A LOW 
PRESSURE TROUGH WILL ACCOMPANY THE WAVE...MOVING FROM NW ONTARIO AT 
00Z INTO UPPER MI BY 12Z. GIVEN HOW FAR EAST THE SHRTWV IS...ANY 
DPVA FORCING IS MINIMAL. ISENTROPIC LIFT PROGS LOOK QUIET AS 
WELL...WITH NEUTRAL LIFT AND ONLY SOME GRADUAL LOWERING IN 
CONDENSATION PRESSURE DEFICITS BY 12Z. THEREFORE...CHANCES FOR 
SYNOPTIC PCPN LOOK VERY LOW AT THIS POINT. EVEN IF PCPN COULD 
FALL...SOUNDINGS DEPICT A FAIRLY DRY LAYER PRESENT BTWN 900-700MB. 
THE ONLY AREA THAT SHOWS THIS LAYER MOISTENING IS OVER EASTERN 
SUPERIOR...AND THUS KEPT SOME 20 POPS THERE. REMOVED CHANCES FOR 
PCPN ELSEWHERE. TEMPS ARE TRICKY SINCE THERE SHOULD BE PLENTY OF 
HIGH CLOUDS AROUND...AS WELL AS INCREASE OF MID CLOUDS AND THEN LOW 
CLOUDS LATE IN THE NIGHT. IN ADDITION...THE APPROACH OF THE SFC 
TROUGH WILL HELP TO KEEP WIND SPEEDS UP. THEREFORE DECIDED TO STAY 
ON THE WARM SIDE OF GUIDANCE. ON A SIDE NOTE...WITH THE LOW CLOUDS 
COME IN LATE AND A WESTERLY FLOW...THERE COULD BE SOME FLURRIES 
DEVELOPING IN THE UPSLOPE AREAS OF THE WESTERN U.P..  
WEDNESDAY...UPPER RIDGE IS SHOWN TO CONTINUE FLATTENING OUT AS THE 
SHRTWV CURRENTLY IN THE GULF OF ALASKA PUSHES SOUTHWARD THROUGH 
BRITISH COLUMBIA. FLOW OVER UPPER MI ALOFT ACTUALLY GOES FROM THE 
CURRENT DUE NORTH TO NORTHWEST BY 00Z THU. THIS NW FLOW WILL HELP TO 
KEEP RELATIVELY WARM AIR AT 850MB OVER THE CWA...RANGING FROM -2C 
WEST TO -8C EAST. OF MORE INTEREST IS BELOW 850MB...WITH MODELS 
HAVING PLENTY OF LOW LEVEL MOISTURE TRAPPED. MOST MODELS ARE ALSO 
PRINTING OUT LIGHT QPF WITH THIS MOISTURE...ESPECIALLY IN NW FLOW 
AREAS. IN FACT...IT IS CLOSE TO BEING UNSTABLE ENOUGH BELOW 850MB TO 
CALL IT LAKE EFFECT. FOR NOW...DECIDED TO FOLLOW THE PREVIOUS FCST 
AND JUST CALL IT FLURRIES FOR UPSLOPE NW FLOW AREAS...SINCE CLOUD 
DEPTHS ARE ONLY EXPECTED AROUND 2000 FT. LATER FCSTS MAY HAVE TO 
INCLUDE SOME LOW CHANCE POPS...THOUGH. THESE LOW CLOUDS SHOULD HELP 
KEEP TEMPS DOWN AS WELL...BUT READINGS ARE STILL EXPECTED TO CLIMB 
ABOVE NORMAL. STAYED WITH A BLEND OF GUIDANCE...WHICH HAS HIGHS IN 
THE MID TO UPPER 20S. 
WED NIGHT INTO THU...MODEL DIFFERENCES ARISE IN THE HANDLING OF THE 
BRITISH COLUMBIA SHRTWV. THE GFS/NAM AND UKMET ARE ALL PRETTY 
PROGRESSIVE...BRINGING IT TO AROUND THE INTERNATIONAL FALLS AREA BY 
00Z FRI. ASSOCIATED WITH THIS SHRTWV IS A SFC LOW...WHICH WOULD 
REACH UPPER MI BY 00Z FRI ACCORDING TO THIS MODEL GROUP. THE 00Z 
ECMWF...ON THE OTHER HAND IS COMPLETELY DIFFERENT...WHICH WAS TRUE 
WITH THE 12Z RUN OF IT AS WELL. IT SUGGESTS THE SHRTWVS MAKES MORE 
OF A DIVE SOUTHWARD INTO SRN ALBERTA...WITH A WEAK NON-ASSOCIATED 
SFC LOW WELL TO THE EAST OVER SE MN AT 00Z FRI. AFTER COORDINATION 
WITH HPC...FOLLOWED THE ECMWF IDEA. ALL MODELS SHOW FOR WED NIGHT A 
COLD FRONT DROPPING SOUTH THROUGH NORTHERN ONTARIO...MOVING INTO 
LAKE SUPERIOR BY 12Z THU. MID-LEVEL FRONTOGENESIS ABOVE AND TO THE 
NORTH OF THIS FRONT MAY SUPPORT SOME LIGHT SYNOPTIC SNOW. WOULD 
EXPECT IT TO THEREFORE MOSTLY FALL ON LAKE SUPERIOR...PERHAPS 
BRUSHING THE EASTERN CWA. OTHERWISE...LOW CLOUDS HANGING AROUND 
COMBINED WITH WEST TO NW LOW LEVEL WINDS SUGGESTS KEEPING FLURRIES 
GOING IN UPSLOPE AREAS. THE CLOUDS WILL ALSO HELP TO KEEP TEMPS 
UP...AND THEREFORE STAYED ON THE WARM SIDE OF GUIDANCE WITH LOWS 
FROM THE MID TEENS TO LOW 20S. THESE READINGS COULD BE WARMED UP IN 
LATER FORECASTS IF IT ENDS UP COMPLETELY CLOUDY ON WEDNESDAY. FOR 
THU...THE FRONT AND MID-LEVEL FRONTOGENESIS SHIFT SOUTH IN RESPONSE 
TO FALLING HEIGHTS ALOFT. THEREFORE...SHIFTED THE LOW CHANCE POPS 
SOUTH AS WELL FOR THU. ECMWF 850MB TEMPS OF -8 TO -10C ARE TOO 
MARGINAL FOR LAKE EFFECT...THEREFORE DID NOT SHOW ANY LOCATION 
HAVING HIGHER POPS THAN 20. CLOUD COVER SHOULD BE PERSISTENT 
AGAIN...BUT WITH WARMER LOWS ON WED NIGHT AND NO SIGNIFICANT COOLING 
ON THU...THU SHOULD END UP BEING THE WARMEST DAY OF THE WEEK. GOING 
HIGHS LOOKED REASONABLE.
THU NIGHT AND FRI...WHETHER YOU FOLLOW THE GFS...UKMET OR 
ECMWF...THERE IS A GENERAL IDEA OF LOW PRESSURE IN THE WESTERN GREAT 
LAKES AREA BY FRI MORNING...WHICH THEN SHIFTS OFF TO THE EASTERN 
GREAT LAKES DURING THE DAY FRI. IN THE WAKE OF THIS LOW...HIGH 
PRESSURE WHICH WILL BE BUILDING OVER THE NEXT COUPLE DAYS FROM NRN 
ALASKA INTO THE YUKON...IS EXPECTED TO NOSE DOWN THROUGH THE PLAINS. 
THIS MEANS ANOTHER SURGE OF ARCTIC AIR FOR UPPER MI...WHICH SHOULD 
ARRIVE BY 00Z SAT. ECMWF 850MB TEMPS FALL TO -12C BY 12Z FRI AND 
THEN TO -20C BY 00Z SAT. THESE FALLING 850MB TEMPS MEANS A 
RESURGENCE OF LAKE EFFECT...FIRST AFFECTING NORTH FLOW AREAS THU 
NIGHT INTO FRI MORNING...THEN SWITCHING TO NW FLOW AREAS FRI AFTN 
INTO FRI NIGHT. KEPT THE GENERAL IDEA OF THE PREVIOUS FORECAST THE 
SAME...WITH THE MAIN ADJUSTMENT TO SLOW DOWN THE HIGHER POPS IN THE 
NORTH CENTRAL U.P. THU NIGHT. ALSO ADDED SOME SMALL CHANCE POPS TO 
THE SOUTHERN U.P. THU NIGHT AND FRI WITH POTENTIAL OF SYNOPTIC SNOW 
AS INDICATED BY THE ECMWF. INITIALLY THE SNOW WILL LIKELY BE QUITE 
FLUFFY...THEN AS THE COLD AIR MOVES IN...THE SNOW SHOULD GET FINER 
AS THE DENDRITIC SNOW GROWTH ZONE FALLS BELOW THE CLOUD BASE. 
POTENTIAL DOES EXIST FOR MODERATE SNOW ACCUMULATIONS OVER HIGHER 
TERRAIN AREAS...AND WILL NOTE THIS IN THE HWO. REGARDING 
TEMPS...RAISED BOTH LOWS AND HIGHS UP A FEW DEGREES DURING THE 
PERIOD TO ACCOUNT FOR THE SLOWER SCENARIO OF COLD AIR COMING IN. 
FURTHER INCREASES MAY BE REQUIRED. HOWEVER...TEMPS SHOULD FALL 
FRIDAY AFTN.
NO CHANGES MADE BEYOND FRI. STILL LOOKS COLD FOR THE WEEKEND INTO 
MONDAY. NEW ECMWF SHOWS THE ARCTIC HIGH THAT HAS BEEN NOSING DOWN 
INTO THE PLAINS MOVING OVERHEAD MONDAY NIGHT. IF THIS COMES 
TRUE...COULD SEE INLAND AREAS GETTING DOWN TO -20F AT LEAST. 
&&
.AVIATION (FOR THE 18Z TAF ISSUANCE)...
KSAW...EXPECT VFR CONDITIONS TO PREVAIL THIS AFTERNOON INTO TONIGHT. 
WAA AHEAD OF A TROUGH APPROACHING THE AREA WILL BRING MVFR CIGS 
BACK INTO THE REGION LATE TONIGHT AND WED MORNING. 
KCMX...NORTHWEST WINDS WILL BACK SOUTHWEST THIS AFTERNOON. AS A 
RESULT...MVFR CONDITIONS ARE EXPECTED TO IMPROVE TO VFR LATE THIS 
AFTERNOON AS ANY LINGERING LAKE EFFECT SNOW ENDS. MVFR CIGS AND 
FLURRIES COULD MOVE BACK IN LATE TONIGHT AS WINDS SHIFT WEST AGAIN 
WITH A TROUGH PASSAGE. 
&&
.MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)...
NORTH WINDS THIS MORNING WILL BACK SOUTHWEST THIS AFTERNOON AS A 
HIGH PRESSURE RIDGE MOVES ACROSS THE AREA. A TIGHTENING SW GRADIENT 
AHEAD OF AN APPROACHING TROUGH WILL INCREASE WINDS TO 30 KT OVER THE 
WRN AND NCNTRL PORTIONS OF LAKE SUPERIOR TONIGHT RESULTING IN 
MODERATE FREEZING SPRAY. BEHIND THE PASSAGE OF A WEAK TROUGH LATE 
TONIGHT...WINDS WILL GENERALLY REMAIN 25 KTS OR LESS THROUGH 
THURSDAY. NORTHERLY WINDS WILL INCREASE TO 30 KT LATE THURSDAY NIGHT 
INTO SATURDAY BEHIND A COLD FRONTAL PASSAGE ALLOWING FOR THE 
FORMATION OF HEAVY FREEZING SPRAY.  
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
  LAKE EFFECT SNOW ADVISORY UNTIL 9 AM EST THIS MORNING FOR MIZ006.
  LAKE EFFECT SNOW WARNING UNTIL 9 AM EST THIS MORNING FOR MIZ002-
     005.
  LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST THIS MORNING FOR MIZ009.
LAKE SUPERIOR...NONE.
LAKE MICHIGAN...NONE.
&&
$$
SYNOPSIS/DISCUSSION...AJ
AVIATION...JLB
MARINE...VOSS