Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 230926
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
526 AM EDT SAT AUG 23 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 446 AM EDT SAT AUG 23 2014

A FAIRLY AMPLIFIED UPPER LEVEL PATTERN OVER THE CONUS FOR THIS TIME
OF THE YEAR...AS UPPER TROUGHS ARE LOCATED OVER THE NORTHERN
ROCKIES AND JUST TO THE EAST OF THE NEW ENGLAND STATES.
MEANWHILE...AN UPPER RIDGE IS LOCATED IN THE CENTRAL CONUS...WITH
THE AXIS RUNNING FROM MISSOURI NORTH TO WESTERN LAKE SUPERIOR. THE
UPPER RIDGE NEAR THE CWA AND THE LIFTING TROUGH OVER THE NORTHERN
ROCKIES WILL BE THE MAIN INFLUENCE ON THE WEATHER FOR THE NEXT
SEVERAL DAYS. CURRENTLY...STILL SEEING SCATTERED/NUMEROUS RAIN
SHOWERS OVER THE CENTRAL PART OF UPPER MICHIGAN TO THE EAST OF THE
UPPER RIDGE AND JUST TO THE EAST OF A WEAK SURFACE TROUGH
STRETCHING NORTH ACROSS CENTRAL WISCONSIN AND INTO WESTERN UPPER
MICHIGAN. THIS PAST EVENING THERE WERE LOCALIZED AREAS OF HEAVY
RAIN IN NORTHEAST IRON COUNTY (RADAR ESTIMATES OF 2.5-4.5 INCHES
AROUND 5-7MI TO THE NORTHEAST OF AMASA). THIS AREA OF RAIN HAS
WEAKENED SLIGHTLY AND SHIFTED FARTHER TO THE EAST (NOW COVERING
SOUTHERN MARQUETTE...CENTRAL DELTA...AND FAR SOUTHWEST SCHOOLCRAFT
COUNTIES)...AS IT APPEARS A WEAK MESO LOW DEVELOPED IN NORTHERN IRON
AND SOUTHERN BARAGA COUNTIES BASED OFF THE RECENT RADAR LOOP.
GETTING A HANDLE ON THE EVOLUTION OF THIS RAIN IS THE MAIN
DIFFICULTY FOR THE NEXT SEVERAL HOURS OF THE FORECAST.

VERY SUBTLE FEATURES CONTROLLING THIS AREA OF SHOWERS...WHICH MAKES
FORECASTING IT OVER THE NEXT 6HRS DIFFICULT. THINK THE SHOWERS ARE
AIDED BY WEAK UPPER DIVERGENCE IN THE RIGHT REAR OF AN UPPER
JET...WEAK 850-700MB Q-VECTOR DIVERGENCE...AND CONVERGENCE ALONG
THE WEAK INVERTED SURFACE TO 925MB TROUGH OVER WEST-CENTRAL UPPER
MICHIGAN. CURRENT THOUGHT FOR THE RAIN OVER THE CENTRAL CWA IS FOR
IT TO SLOWLY MOVE EAST AND MAYBE A LITTLE NORTH THROUGH THE MORNING
HOURS DUE TO THE LIGHT FLOW WITHIN THE CLOUD LAYER. THEN...AS THE
UPPER RIDGE AMPLIFIES AND PUSHES NORTH TOWARDS THE AFTERNOON HOURS
WOULD EXPECT THE SHOWERS TO DIMINISH AND SHIFT NORTHEAST AS LOW
LEVEL SOUTHEASTERLY FLOW BEGINS TO INCREASE. THUS...HAVE FOLLOWED
THAT IDEA FOR POPS TODAY ALTHOUGH CONFIDENCE QUICKLY DECREASES
THROUGH THE DAY WITH THE SMALL SCALE INFLUENCES ON THE SHOWERS.
BRIEF HEAVY RAIN IS STILL POSSIBLE (PWAT VALUES AROUND 175 PERCENT
OF NORMAL...SLOW MOVEMENT...AND RADAR INSTANTANEOUS RAIN RATE
SHOWING 0.75-1.5 IN/HR)...BUT DON/T EXPECT ANY HEAVY RAINS LIKE
WAS SEEN LAST EVENING. ALSO FOR THIS MORNING...HAVE SEEN FOG
DEVELOP IN SOME LOCATIONS...ESPECIALLY AWAY FROM THE RAIN AND THE
WEAK MIXING IT HAS PROVIDED...AND THAT SHOULD CONTINUE INTO THE
FIRST PART OF THE MORNING HOURS BEFORE DIURNAL HEATING DIMINISHES
THE FOG.

OTHERWISE...EXPECT CLOUDY CONDITIONS FOR MUCH OF THE DAY...AS LOW
LEVEL MOISTURE WILL STAY IN PLACE FOR MUCH OF UPPER MICHIGAN. WITH
THE SOUTHEASTERLY FLOW INCREASING THROUGH THE AFTERNOON...IT WILL
TRY TO FOCUS THE DEEPER MOISTURE TO THE WESTERN THIRD OF THE CWA.
SOME DRYING IN THE MID LEVELS COULD LEAD TO BREAKS IN THE CLOUDS
OVER THE EASTERN THIRD OF THE CWA. DID LEAVE SOME SLIGHT CHANCE OF
SHOWERS/THUNDERSTORMS OVER THE INTERIOR WEST HEADING INTO THE
AFTERNOON ALONG THE SURFACE TROUGH. HIGHS WILL BE IN THE 70S FOR
MOST LOCATIONS AND IT WILL BE HUMID WITH DEWPOINTS IN THE LOW-MID
60S.

FOR TONIGHT...EXPECT MOST OF THE PRECIP TO STAY OFF TO THE WEST
(DUE TO THE UPPER RIDGE BUILDING OVER THE CWA) AND CLOSER TO THE
SHORTWAVE AND ASSOCIATED SURFACE LOW LIFTING NORTH THROUGH THE
EASTERN DAKOTAS. KEPT THE POPS OVER THE WESTERN THIRD OF LAKE
SUPERIOR THROUGH THE NIGHT...BUT DID SNEAK THEM EASTWARD INTO
WESTERN GOGEBIC/ONTONAGON COUNTIES TOWARDS SUNRISE. THE INCREASING
SOUTHEASTERLY FLOW ALOFT WILL LIKELY LEAD TO NEAR SURFACE WINDS
INCREASING OVERNIGHT AND HELP LIMIT THE VISIBILITY REDUCTION FROM
FOG. STILL EXPECT SOME FOG...BUT THINK IT WILL TREND MORE TOWARDS A
LOW STRATUS. HAVE PATCHY FOG IN THE FAVORED LOCATIONS WITH THE
SOUTHEASTERLY WIND AND AREAS OF FOG WHERE THE UPSLOPE FLOW WILL
PROVIDE ADDITIONAL LIFT AND PUT BASES NEAR THE SURFACE.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 525 AM EDT SAT AUG 23 2014

TROF IS CURRENTLY SETTLING INTO THE ROCKIES WHILE DOWNSTREAM RIDGE
IS BUILDING OVER THE MISSISSIPPI RIVER VALLEY. MAIN PIECE OF ENERGY
IN THE TROF WILL LIFT NE INTO THE DAKOTAS SUN AND THEN INTO NRN
ONTARIO MON/MON NIGHT. THIS WILL SUPPRESS AND FORCE THE RIDGE
EASTWARD SO THAT THE AXIS EXTENDS THRU THE LOWER LAKES TO NEW
ENGLAND BY LATE MON. ADDITIONAL ENERGY WILL DROP INTO THE WRN TROF
EARLY NEXT WEEK...AND THEN THE TROF WILL BECOME MORE PROGRESSIVE FOR
THE REMAINDER OF THE WEEK. END RESULT OF THESE CHANGES WILL BE
WARM/HUMID WEATHER INTO THE EARLY PART OF NEXT WEEK...AND THEN A
CHANGE TO COOLER WEATHER FOR THE MIDDLE AND END OF THE WEEK AS THE
TROF PASSES. AS FOR PCPN...THERE WILL BE SOME INCREASE IN PCPN
POTENTIAL LATE SUN INTO MON AS THE MAIN PIECE OF ENERGY TRACKS FROM
THE DAKOTAS INTO NRN ONTARIO. HOWEVER...SHORTWAVE WILL BE TAKING A
TRACK FAR ENOUGH W AND N OF THE AREA TO PROBABLY PRECLUDE A
SIGNIFICANT PCPN CHC AS HEIGHT FALLS WILL BE WEAK AS COLD/OCCLUDED
FRONT SWINGS E ACROSS THE UPPER LAKES. ANOTHER SHOT OF PCPN MAY
OCCUR AROUND MIDWEEK AS WRN TROF PROGRESSES EASTWARD.

BEGINNING SUN...DURING THE MORNING...ISOLATED SHRA/TSRA MAY AFFECT
FAR WRN UPPER MI WHICH WILL BE ON THE ERN FRINGE OF LOW-LEVEL JET
AIMED N THRU MN. TAIL OF SHORTWAVE LIFTING THRU MN INTO NRN ONTARIO
MAY PROVIDE SOME SUPPORT AS WELL. OTHERWISE...MAIN PIECE OF ENERGY
IN THE WRN TROF WILL LIFT THRU THE WRN DAKOTAS TOWARD SRN MANITOBA.
SFC LOW WILL TAKE A SIMILAR TRACK...AND DURING THE DAY SUN...THE
ASSOCIATED COLD/OCCLUDED FRONT WILL REMAIN WELL W OF UPPER MI. BY
00Z MON...THE ROUGHLY N-S ORIENTED FRONT WILL ONLY BE HALFWAY ACROSS
MN. WITH FRONT WELL TO THE W...LITTLE/NO HEIGHT FALLS AND PROBABLY A
CAPPED ENVIRONMENT THRU THE AFTN...A DRY DAY SHOULD BE THE RULE.
HOWEVER...OPTED TO INCLUDE SLIGHT CHC POPS FAR W LATE IN THE AFTN AS
WEAK HEIGHT FALLS/DEEP LAYER FORCING BEGIN TO SPREAD TOWARD UPPER
MI. FCST SOUNDINGS SUGGEST MAX TEMPS GENERALLY IN THE LOW/MID 80S.
IT WILL BE UNCOMFORTABLY HUMID.

ON SUN NIGHT...WEAK HEIGHT FALLS ON THE ORDER OF 20-40M SPREAD INTO
UPPER MI AS SYSTEM LIFTS INTO SRN MANITOBA. FRONTAL BOUNDARY WILL
ALSO PUSH INTO WRN UPPER MI LATE IN THE NIGHT. WITH BEST DEEP LAYER
FORCING WELL OFF TO THE NW...BELIEVE SHRA/TSRA ALONG BOUNDARY SHOULD
WEAKEN AND BECOME LESS WIDESPREAD AS THEY ACCOMPANY FRONT INTO UPPER
MI SUN NIGHT. NORMAL NIGHTTIME DECREASE IN INSTABILITY WILL ALSO
WORK TO DIMINISH PCPN UNLESS CONVECTION BECOMES ELEVATED...THOUGH
THAT IS NOT LIKELY. THAT SAID...THERE WILL STILL BE SUFFICIENT
INSTABILITY IN THE PRESENCE OF 35-40KT DEEP LAYER SHEAR TO SUPPORT
THE POTENTIAL OF ORGANIZED STRONG STORMS AND PERHAPS A SVR STORM IF
SFC BASED CONVECTION HOLDS TOGETHER.

FRONTAL BOUNDARY CONTINUES EASTWARD ON MON...BUT THERE IS
DISAGREEMENT ON HOW FAR E FRONT WILL MOVE. THE GFS HOLDS UP FRONT
OVER THE FCST AREA MON WHILE THE GEM/ECMWF DRIFT FRONT E...EXITING
THE ERN FCST AREA MON EVENING. DESPITE FRONT HANGING UP...GFS STILL
SHOWS RATHER AGGRESSIVE MIDLEVEL DRYING PUSHING ACROSS THE FCST AREA
MON. SO...CONSENSUS SUPPORTS A TREND TO DRY WEATHER FROM W TO E MON
INTO MON EVENING. THE ERN FCST AREA WILL HAVE A CHC TO BUILD
INSTABILITY BEFORE FRONT AND/OR MID LEVEL DRYING ARRIVES...SO WILL
SHOW AN INCREASE IN POPS OVER THE E FOR THE AFTN WHILE THE W BECOMES
MOSTLY SUNNY. DEEP LAYER SHEAR OF 30-40KT WILL SUPPORT POTENTIAL FOR
ORGANIZED STRONG STORMS WITH THE POTENTIAL FOR ISOLD SVR.

ON MON NIGHT...THE GFS BRINGS SHORTWAVE ENERGY INTO THE UPPER LAKES
IN WSW FLOW...AND THE FRONT IT HANGS UP OVER THE AREA MON BECOMES A
FOCUSING POINT FOR NEW PCPN DEVELOPMENT. MEANWHILE...THE GEM/ECMWF
KEEP THE AREA DRY WITH FRONTAL BOUNDARY FARTHER TO THE S AND E. WILL
LEAN TOWARD THE DRIER SCENARIO FOR NOW...WITH ONLY SCHC POPS ACROSS
THE S AND E.

THE UNCERTAINTY THAT INCREASES MON NIGHT CONTINUES TO GROW THRU
MIDWEEK. THE GFS...AS IT HAS FOR A NUMBER OF RUNS...MAINTAINS A MORE
AMPLIFIED TROF PROGRESSING ACROSS THE CONUS WITH THE RESULT BEING A
MORE WELL-DEFINED SFC WAVE IN MOST RUNS TRACKING ALONG FRONTAL
BOUNDARY INTO THE GREAT LAKES. THE ECMWF AND GEM HAVE BEEN FLATTER
WITH THE PATTERN EXCEPT FOR A RUN OR TWO. THE FLATTER PATTERN
RESULTS IN THE FRONTAL BOUNDARY FARTHER S AND E WITH WEAKER SFC
WAVES TRACKING ALONG IT AND THUS LESS PCPN POTENTIAL FOR UPPER
MI...PARTICULARLY ACROSS THE N AND W. WILL CONTINUE TO UTILIZE A
SIMPLE CONSENSUS UNTIL BETTER MODEL AGREEMENT DEVELOPS. THIS RESULTS
IN CHC POPS SPREADING INTO THE SW FCST AREA TUE AND THEN ACROSS THE
AREA TUE NIGHT THRU WED NIGHT. THE LATE WEEK PERIOD SHOULD TURN DRY
IN THE WAKE OF THE TROF.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 130 AM EDT SAT AUG 23 2014

STRENGTHENING INVERSION TONIGHT AND PLENTY OF MOISTURE BENEATH THE
INVERSION WILL ALLOW FOR MORE LOW STRATUS AND FOG TO DEVELOP LATE
TONIGHT INTO SATURDAY MORNING. VLIFR CONDITIONS HAVE ALREADY WORKED
INTO KIWD EARLY THIS EVENING AND WOULD EXPECT THESE TO PERSIST INTO
SAT MORNING. AT BOTH KCMX AND KSAW...EXPECT CONDITIONS TO LOWER TO
IFR OVERNIGHT. ISOLD SHRA WILL BE AROUND THE AREA THIS EVENING BUT
SHOULD ONLY AFFECT KSAW BRIEFLY SO INCLUDED -SHRA MENTION IN FIRST
FEW HRS OF TAF. WITH DIURNAL HEATING EXPECT SLOW IMPROVEMENT TO MVFR
CONDITIONS AT BOTH KIWD AND KCMX AND TO VFR AT KSAW BY SAT AFTERNOON.
CONDITIONS WILL LIKELY LOWER AGAIN SAT EVENING WITH SOME COOLING AND
LINGERING MOISTURE.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 446 AM EDT SAT AUG 23 2014

A LOW PRESSURE SYSTEM LIFTING NORTH FROM THE CENTRAL PLAINS TODAY
AND INTO SOUTHERN MANITOBA BY SUNDAY MORNING WILL LEAD TO A
TRANSITION FROM LIGHT NORTHEAST WINDS TO EAST-SOUTHEAST WINDS UNDER
20KTS BY SUNDAY. AS THIS LOW MOVES TO JAMES BAY BY MONDAY
NIGHT...EXPECT A TROUGH TO MOVE EAST THROUGH LAKE SUPERIOR ON MONDAY
AND SHIFTING THE WINDS TO A WESTERLY DIRECTION BY MONDAY NIGHT.
THERE COULD BE BRIEF PERIODS OF GUSTS TO 25KTS JUST AHEAD AND BEHIND
THE FRONT. THE WESTERLY WINDS UNDER 20KTS WILL CONTINUE THROUGH THE
MIDDLE OF NEXT WEEK AS THE TROUGH SLOWLY SAGS SOUTHEAST ACROSS THE
GREAT LAKES REGION.

MOIST AIR OVER THE UPPER GREAT LAKES REGION CONTINUES TO PRODUCE
FOG OVER PORTIONS OF LAKE SUPERIOR. AS SOUTHERLY FLOW DEVELOPS ON
SUNDAY...MORE MOISTURE WILL MOVE OVER THE LAKE AND LIKELY LEAD TO
MORE WIDESPREAD FOG OVER THE NORTHEAST HALF OF LAKE SUPERIOR. OBS
THIS PAST EVENING INDICATED SOME AREAS OF DENSE FOG OVER THE CENTRAL
LAKE AND MAY NEED TO ISSUE A DENSE FOG ADVISORY IF COVERAGE EXPANDS.
DRIER AIR ARRIVING BEHIND THE FRONT ON MONDAY SHOULD BRING AN END TO
THE FOG ON MONDAY NIGHT.
&&

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

$$

SHORT TERM...SRF
LONG TERM...ROLFSON
AVIATION...VOSS
MARINE...SRF





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