Area Forecast Discussion
Issued by NWS Marquette, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KMQT 011215
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
815 AM EDT WED OCT 1 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 526 AM EDT WED OCT 1 2014

UPPER RIDGE OVER THE GREAT LAKES REGION CONTINUES TO SLOWLY PUSH
EAST THIS MORNING AS LOW PRESSURE SYSTEM LIFTS INTO THE CANADIAN
PRAIRIE PROVINCES. THE RIDGE WILL GRADUALLY MOVE EAST OF THE GREAT
LAKES REGION TONIGHT AS THE LOW SHIFTS INTO EXTREME NORTHWEST
ONTARIO. LOW CLOUDS AND AREAS OF DRIZZLE CONTINUE EARLY THIS MORNING
OVER CENTRAL AND EASTERN UPPER MICHIGAN AS SOUTHEAST FLOW CONTINUES
ON BACKSIDE OF SFC RIDGE. DRIZZLE EXPECTED TO END WITH DAYTIME
MIXING BUT CLOUD COVER WILL PERSIST THROUGHOUT MUCH OF THE DAY AS
LATEST BUFKIT SOUNDINGS SHOW PLENTY OF LOW LEVEL MOISTURE TO PERSIST
ACROSS THE AREA THROUGH THE DAY.

MAIN FORECAST CHALLENGE CONCERNS PRECIPITATION. WHILE THE BEST
FORCING TO EXIST W OF THE AREA CLOSER TO THE UPPER LEVEL
SUPPORT...THE AREA WILL SEE A NARROW BAND OF MOISTURE ADVECTION
AHEAD OF A 5H TROF THAT WILL BEGIN SWINGING TOWARD THE REGION LATER
TODAY. INCREASING 850-500 MB Q VECTOR CONVERGENCE AND 80 KT JET
ROUNDING THE BASE OF THE TROF SUPPORTS LIKELY POPS OVER THE WRN U.P.
THIS AFTERNOON. TIMING THE QUESTION...LATEST MODELS TRENDED SLIGHTLY
SLOWER WITH THE ARRIVAL OF THE PRECIPITATION AND HAVE IN GENERAL
FOLLOWED THAT TREND. THUS MAIN FOCUS FOR PCPN TO BE OVER THE WEST
FOR THE DAY AND MAINLY IN THE AFTERNOON. AS FOR TEMPS...PERSISTENT
CLOUD COVER CENTRAL AND EAST WILL HOLD TEMPERATURES DOWN SLIGHTLY
DESPITE SLIGHT WARM AIR ADVECTION.

FOR TONIGHT...PRECIPITATION SPREADS ACROSS THE AREA FROM WEST TO
EAST AS THE 5H TROF MOVES IN. CAPES AND LIFTED INDICES NOT
VERY IMPRESSIVE BUT WITH NOSE OF 100KT 250 MB JET MOVING IN AND WITH
PROXIMITY OF THE 5H TROF AXIS CANNOT RULE OUT A SLIGHT CHANCE OF
THUNDER WITH THIS SYSTEM. WITH SW FLOW AT 850 MB...AND TEMPS HOLDING
10-12 C...ALONG WITH THE CLOUD COVER PERSISTING THROUGH THE NIGHT
TEMPS WILL HOLD UP WELL ABOVE SEASONAL NORMALS...GENERALLY IN THE
UPPER 40S TO MID 50S.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 526 AM EDT WED OCT 1 2014

AN ACTIVE LATE WEEK PERIOD IS IN THE OFFING AS AN AMPLIFIED TROF
DEVELOPS OVER THE MISSISSIPPI VALLEY. THIS WILL SPUR THE DEVELOPMENT
OF A STRONG AUTUMN STORM SYSTEM THAT WILL BE STRENGTHENING AS IT
LIFTS THRU THE UPPER GREAT LAKES REGION FRI. THRU THE WEEKEND AND ON
INTO THE EARLY PART OF NEXT WEEK...FCST AREA WILL BE UNDER THE
INFLUENCE OF A DEEP TROF EXTENDING FROM HUDSON BAY S THRU THE GREAT
LAKES REGION. THESE CHANGES WILL RESULT IN NEAR NORMAL TEMPS
INITIALLY FALLING TO BLO NORMAL FOR THE WEEKEND...POTENTIALLY WELL
BLO NORMAL. STORM SYSTEM SHOULD BRING GENERALLY MDT PCPN AMOUNTS TO
THE FCST AREA...BUT PCPN COULD BE HVY OVER PARTS OF THE AREA
DEPENDING ON THE TRACK OF THE SFC LOW. UNSETTLED WEATHER WILL
CONTINUE DURING THE WEEKEND UNDER CYCLONIC FLOW WITH A LAKE
COMPONENT TO THE PCPN AS COLD AIR MASS INVADES THE AREA. IN
FACT...AIR SHOULD BE COLD ENOUGH FOR SOME SNOW TO OCCUR AS WELL...AT
LEAST OVER HIGHER TERRAIN. LOOKING FARTHER AHEAD...HOW QUICKLY THE
PATTERN DEAMPLIFIES/BECOMES MORE PROGRESSIVE NEXT WEEK WILL BRING
UNCERTAINTY TO TEMP/PCPN FCST AFTER THE EARLY PART OF THE WEEK...BUT
IT DOES APPEAR NW FLOW WILL DOMINATE...SO BLO NORMAL TEMPS SHOULD
OVERALL BE THE RULE NEXT WEEK.

LOOKING CLOSER AT SOME OF THE DETAILS...MID/UPPER LEVEL TROF WILL BE
AMPLIFYING AS IT MOVES FROM THE WRN PLAINS THU TO THE MISSISSIPPI
VALLEY FRI. INTERACTION OF LEAD SHORTWAVE ENERGY IN THE TROF AND A
MUCH STRONGER SHORTWAVE DROPPING SE FROM THE NRN ROCKIES WILL
DETERMINE TRACK OF DEVELOPING SFC LOW PRES AND HOW QUICKLY IT
DEEPENS. HEADING INTO THE WEEKEND...COMPLEX INTERACTION WITH ANOTHER
STRONG SHORTWAVE DROPPING SE FROM SCNTRL CANADA WILL ADD MORE
UNCERTAINTY TO THE EVOLUTION OF THE SFC LOW AND THE WHOLE EVOLUTION
OF THE MID/UPPER LEVEL TROF AND DEVELOPING MID LEVEL LOW SOMEWHERE
OVER THE GREAT LAKES REGION. AT THIS POINT...CONSENSUS OF RECENT
MODEL RUNS SUGGESTS COLD FRONT/OCCLUDED FRONT INITIALLY TIED TO THE
STRONG SHORTWAVE CURRENTLY LIFTING INTO SCNTRL CANADA WILL MAKE IT
TO AT LEAST WRN UPPER MI AND PROBABLY TO CNTRL LAKE SUPERIOR THU.
THEN...IN RESPONSE TO THE STRONG SHORTWAVE DROPPING SE FROM THE NRN
ROCKIES TOWARD THE MID/UPPER MISSISSIPPI VALLEY...A SFC WAVE WILL
ORGANIZE ALONG THE FRONT OVER THE UPPER MISSISSIPPI VALLEY LATE THU
AND THEN TRACK NNE ACROSS CNTRL UPPER MI THU NIGHT/EARLY FRI. ON
THU...STALLING FRONTAL BOUNDARY AND LIMITED FORCING SUGGESTS
GENERALLY NOTHING MORE THAN CHC POPS...THOUGH WILL INCLUDE LIKELY
POPS IN THE MORNING OVER THE E ALONG DIMINISHING MOISTURE TRANSPORT
RIBBON. MUCH OF THE W MAY SEE DRY WEATHER FOR THE BULK OF THE DAY.
IF ORGANIZING SFC LOW PRES TO THE SSW IS QUICKER TO LIFT NNE...THEN
MORE WIDESPREAD SHRA ACTIVITY WILL SPREAD INTO THE AREA IN THE AFTN.
THU NIGHT WILL BE THE MAIN EVENT PCPN-WISE AS STRENGTHENING SFC LOW
PRES MOVES ACROSS THE AREA WHILE DEEP LAYER FORCING/MOISTURE
TRANSPORT INCREASES IN RESPONSE TO DEEPENING TROF/HEIGHT FALLS INTO
THE UPPER MISSISSIPPI VALLEY/WRN GREAT LAKES. THERE`S NOT MUCH IN
THE WAY OF INSTABILITY...BUT CAN`T RULE OUT SOME THUNDER...MAINLY
ALONG E OF EXPECTED SFC LOW TRACK.

FRI INTO FRI NIGHT...NAM LOOKS OVER DEVELOPED WITH A DEEPER MORE
CONSOLIDATED MID LEVEL LOW SETTING UP SHOP OVER LAKE SUPERIOR/UPPER
MI. RESULT IS SFC LOW PRES NEVER MOVING OFF LAKE SUPERIOR THRU 12Z
SAT. ALL OTHER GUIDANCE MAINTAIN A BROADER MID LEVEL LOW OR MORE
THAN ONE CENTER AS A RESULT OF MORE SEPARATION OF THE MAIN
SHORTWAVES IN THE TROF...AND IN PARTICULAR THE STRONGER DIGGING OF
THE SHORTWAVE MOVING SE FROM THE NRN ROCKIES THRU THE MID/UPPER
MISSISSIPPI VALLEY AND THEN TOWARD THE OHIO VALLEY. GIVEN LOW
CONFIDENCE IN HOW THE INTERACTION OF ALL THE SHORTWAVES WILL PLAY
OUT...LARGELY UTILIZED A MIX OF THE 00Z GFS/12Z ECMWF AND SOME 00Z
GEM TO AVOID BEING OVERLY DEPENDENT ON THE UNCERTAIN DETAILS OF ANY
ONE SPECIFIC MODEL. 00Z ECMWF UNFORTUNATELY ADDED MUCH MORE
UNCERTAINTY TO FCST AS IT TAKES A WEAKER SFC LOW THRU UPPER MI THU
NIGHT AND THEN KEYS ON THE STRONGER SHORTWAVE DIGGING TOWARD THE
OHIO VALLEY TO GENERATE A STRONGER SFC LOW WHICH DEVELOPS OVER LWR
MI FRI AND THEN TRACKS N OF LAKE HURON FRI NIGHT. IF THIS
OCCURS...MAIN PCPN EVENT STILL OCCURS THU NIGHT...BUT PCPN FIELDS
THEN REORGANIZE TO BRING ANOTHER ROUND OF AT LEAST MDT PCPN INTO THE
ERN FCST AREA FRI AFTN INTO EARLY SAT. FOR NOW...THIS CHANGE IN
CONTINUITY WILL NOT BE FACTORED SIGNIFICANTLY INTO THE FCST. PCPN
WILL BE WINDING DOWN BY FRI MORNING WITH CAA GETTING UNDERWAY AS LOW
PRES LIFTS N OF UPPER MI. CYCLONIC FLOW AND DEVELOPING INSTABILITY
OVER LAKE SUPERIOR WILL RESULT IN LAKE ENHANCED SHRA DEVELOPING OFF
WRN LAKE SUPERIOR DURING THE DAY FRI WHILE PCPN DIMINISHES
ELSEWHERE.

CHILLY CYCLONIC FLOW WITH 850MB TEMPS FALLING TO -3 TO -5C FRI
NIGHT/SAT WILL SPELL LAKE ENHANCED PCPN. WARMER WATER TEMPS OVER WRN
LAKE SUPERIOR AND MORE SUBSTANTIAL UPSLOPING WILL RESULT IN STEADIER
SOMEWHAT HEAVIER PCPN OVER WRN UPPER MI. FCST SOUNDINGS/THICKNESS
AND WETBULB TEMPS SUPPORT PCPN MIXING WITH OR EVEN CHANGING TO ALL
SNOW OVER THE HIGH TERRAIN...LATER FRI NIGHT/SAT MORNING. MAY SEE A
LITTLE SNOW ACCUMULATION ON THE GRASS.

LAKE EFFECT/LAKE ENHANCED PCPN WILL CONTINUE SAT NIGHT/SUN WITH SOME
SNOW IN THE HIGHER TERRAIN AT NIGHT AND INTO THE MORNING HRS.

ON ANOTHER NOTE...WITH A LENGTHY PERIOD OF STRONG NW WINDS ON LAKE
SUPERIOR...INCLUDING GALES FOR A TIME...AND HIGH LAKE LEVELS (LAKE
SUPERIOR IS CURRENTLY ABOUT 6 INCHES BLO THE RECORD HIGH FOR THIS
TIME OF YEAR)...BEACH EROSION/FLOODING MAY BECOME A PROBLEM FOR
AREAS THAT ARE EXPOSED TO WAVES GENERATED BY NW WINDS.

UPPER LAKES WILL STILL BE IN THE TROF MON AND THEN MODEL UNCERTAINTY
GROWS SIGNIFICANTLY ON HOW FAST THE FLOW BECOMES MORE PROGRESSIVE
TUE AND BEYOND. AT THIS POINT...IT APPEARS THERE MAY BE A SHORTWAVE
OR TWO MOVING THRU THE AREA TO BRING SOME PCPN.
&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 814 AM EDT WED OCT 1 2014

LOWER CEILINGS/VIS THANKS TO PLENTY OF MOISTURE ON S DOWNSLOPE WINDS
AT SAW WILL IMPROVE THIS MORNING WITH DAYTIME HEATING/MIXING.
ALREADY SEEING SOME IMPROVEMENTS TO THE S CEILING WISE. OTHERWISE
THE MAIN STORY WILL BE THE APPROACHING WET WEATHER FOR LATER TODAY
THROUGH TONIGHT...WHICH WILL BRING ANOTHER ROUND OF IFR TO LIFR
CEILINGS/VIS AFTER 08Z THURSDAY MORNING. WINDS SHOULD STAY BELOW
20KTS THROUGH THE PERIOD.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 526 AM EDT WED OCT 1 2014

HIGH PRESSURE WILL KEEP WINDS AND WAVES DOWN OVER THE GREAT LAKES
UNTIL THE NEXT SYSTEM DEVELOPS OVER THE CENTRAL PLAINS ON THURSDAY
AND THEN LIFTS NORTHEAST AND DEEPENS OVER THE UPPER GREAT LAKES BY
FRIDAY MORNING. THIS FEATURE WILL BRING GALES TO MUCH OF LAKE
SUPERIOR ON FRIDAY WITH THE STRONG WINDS PERSISTING INTO SATURDAY.
THE SURFACE LOW WILL LINGER OVER NORTHERN ONTARIO THROUGH THE WEEKEND
WHILE GRADUALLY WEAKENING. WINDS WILL STILL REMAIN AT OR ABOVE 20
KNOTS THROUGH SUNDAY OVER ALL BUT FAR WESTERN LAKE SUPERIOR.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&

$$

SHORT TERM...RJT
LONG TERM...ROLFSON
AVIATION...KF
MARINE...RJT





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.