Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 230846
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
446 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...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 347 PM EDT FRI AUG 22 2014

LOOKS LIKE A PERIOD OF WARMER...MORE HUMID WX TYPICAL OF MID SUMMER
WL DOMINATE INTO EARLY NEXT WEEK AS A HI AMPLITUDE UPR RDG BLDS INTO
THE GREAT LKS DOWNSTREAM OF DEEPENING TROF ACRS THE W. BEST CHC OF
PCPN APPEARS WL BE ON SUN NGT/MON AS A SHRTWV RIDING OVER THE RDG
DRAGS A COLD FNT INTO THE UPR LKS AND AGAIN ON TUE INTO WED AS
ANOTHER SHRTWV APRCHS FM THE W. ALTHOUGH THE LONGER RANGE GUIDANCE
INDICATES A MORE ZONAL FLOW WL DVLP NEXT WEEK...THERE IS POOR
EXTENDED MODEL AGREEMENT AND RUN-TO-RUN CONSISTENCY ON THE DETAILS
OF THIS EVOLUTION.

SAT NGT/SUN...PERSISTENT UPR RDG AXIS STRETCHING FM THE SCENTRAL
CONUS THRU THE GREAT LKS TO JAMES BAY WL PREVAIL THRU THIS TIME AND
SUPPORT A SFC-H85 HI CENTERED NEAR MONTREAL. AT THE SAME TIME...A
SHRTWV WL BE LIFTING NEWD FM THE CENTRAL ROCKIES INTO THE NRN
PLAINS...WITH ACCOMPANYING SFC LO FCST TO MOVE NEAR LK WINNIPEG BY
00Z MON. ALTHOUGH THE SLY FLOW IN THE WARM SECTOR BTWN THIS LO AND
THE HI TO THE E WL ADVECT WARMER...MORE HUMID AIR INTO THE UPR LKS
WITH H85 TEMPS FCST AS HI AS ARND 20-23C...ABSENCE OF HGT FALLS SO
FAR E OF THE SHRTWV TRACK AND H85 LLJ/HIER THETA E AXIS STILL IN MN
AT 12Z SUN SHOULD MAINTAIN DRY WX OVER UPR MI. CURRENT FCST HAS SOME
SCHC POPS EXTENDING AS FAR E AS THE WRN LAND CWA DURING THIS TIME...
CONSISTENT WITH THE FCST E EDGE OF THE DEEP LYR QVECTOR CNVGC
ACCOMPANYING THE DYNAMIC FORCING/MSTR ADVCTN TO THE W. HUMID AIRMASS
WL SUPPORT PATCHY FOG DURING THE DIURNAL COOLING ON SAT NGT INTO SUN
MRNG.

SUN NGT THRU MON NGT...AS THE SHRTWV/SFC LO RIDE NEWD AND INTO NW
ONTARIO...ATTENDANT COLD FNT IS FCST TO MOVE INTO WRN LK SUP SUN NGT
AND THEN INTO UPR MI ON MON. THE 12Z GFS HAS SLOWED DOWN THE
PROGRESSION OF THIS FNT WITH A MORE AMPLIFIED RDG/SW FLOW ALF
PARALLEL TO THE FNT AND INDICATES THE FNT WL STALL OVER THE CWA ON
MON NGNT. ON THE OTHER HAND...THE 12Z CNDN/ECMWF MODELS REMAIN
CONSISTENT WITH THEIR EARLIER RUNS SHOWING THE FNT MOVING THRU THE
CWA BY 00Z TUE. AS FOR POPS...WARM CONVEYOR BELT MSTR RIBBON/AXIS OF
DEEP LYR QVECTOR CNVGC IS FCST TO MIGRATE SLOWLY E ACRS THE CWA WITH
THE FNT. THE 12Z CNDN/ECMWF SHOW THE MOST AGGRESSIVE MID LVL DRYING/
DEEP LYR QVECTOR DVGC ON MON AFTN...AND EVEN THE SLOWER GFS
INDICATES SOME MID LVL DRYING DURING THE AFTN. WL GO NO HIER THAN
CHC POPS GIVEN THE TRACK OF THE SHRTWV/SFC LO/MOST VIGOROUS DPVA AND
DEEP LYR FORCING SO FAR TO THE N THAT CONTRIBUTES TO 12HR H5 FALLS
NO MORE THAN 30-40M DURING THIS TIME EVEN BY THE MOST AGGRESSIVE
CNDN MODEL. GIVEN THE HI AMPLITUDE RDG...SUSPECT THE SLOWER GFS IS
ON THE RIGHT TRACK...SO SLOWED DOWN THE FROPA TIMING/DRYING TREND...
WITH HIER POPS/LESS COOLING ON MON NGT. EXPECT THE HIEST CHC POPS
OVER THE E HALF ON MON AFTN AS THE ARRIVAL OF THE FNT WL COINCIDE
WITH PEAK DIURNAL HEATING. EXPECT TEMPS TO RUN WELL ABV NORMAL ON
SUN NGT THRU MON NGT. SUN NGT SHOULD BE PARTICULARY WARM RELATIVE TO
AVG WITH A STEADY SSW FLOW AND MOISTER ENVIRONMENT WITH FCST PWAT AS
HI AS 1.75 INCHES /175-200 PCT OF NORMAL/.

EXTENDED...THE UPR FLOW IS FCST BY MOST OF THE LONGER RANGE MODEL
GUIDANCE/ENSEMBLES TO TURN MORE ZONAL ALONG THE CNDN BORDER
FOLLOWING THE PASSAGE OF THE SHRTWV THRU NW ONTARIO/UPR LKS FROPA ON
MON/MON NGT. NOT SURPRISINGLY...THERE HAS BEEN POOR MODEL AGREEMENT
AND RUN-TO-RUN CONSISTENCY REGARDING THE DETAILS OF THE FCST FOR NEXT
WEEK. FOR INSTANCE...RECENT GFS RUNS HAVE SHOWN A MORE AMPLIFIED
SHRTWV TRACKING THRU THIS FLOW AND BRINGING BETTER PCPN CHCS TO THE
AREA FM LATE TUE INTO AT LEAST THU...BUT THE 12Z GFS HAS BACKED AWAY
FM THIS A BIT. ON THE OTHER HAND...THE 00Z CNDN MODEL FCST ONLY A
WEAK SHRTWV PASSING THRU THE UPR LKS ON WED WITH ALL PCPN REMAINING S
OF THE FA. NOW THE 12Z MODEL GENERATES A FCST SIMILAR TO THE ONE
SHOWN BY THE MORE VIGOROUS 06Z GFS. GIVEN THE POOR CONTINUITY AND
CONSISTENCY...WL RELY ON MODEL CONSENSUS FOR THE EXTENDED FCST.
&&

.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...KC
AVIATION...VOSS
MARINE...SRF






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