Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 301700
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
100 PM EDT THU APR 30 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 352 AM EDT THU APR 30 2015

A 500MB LOW HAS MOVED ACROSS THE ERN CWA AND INTO LOWER MI...WITH
LINGERING LOW LEVEL MOISTURE MAKING ITS WAY ACROSS ERN UPPER MI IN
THE N-NE FLOW AHEAD OF THE SFC RIDGE OVER WRN LAKE SUPERIOR. LOW
LEVEL MOISTURE/UPSLOPE FORCING MAY RESULT IN A FEW LIGHT SHOWERS
BEFORE SUNRISE TODAY...BUT CERTAINLY NO SIGNIFICANT PRECIP AMOUNTS
EXPECTED. ANOTHER COOLER DAY TODAY (SIMILAR TO WEDNESDAY) ESPECIALLY
NEAR LAKE SUPERIOR WITH BREEZY N WINDS. CLOUDS WILL LINGER OVER
MAINLY THE NCENTRAL AND E INTO THIS AFTERNOON...WITH CLEARING
EXPECTED LATE THIS AFTERNOON AND EVENING AS THE SFC RIDGE SHIFTS E
AND IS REINFORCED BY AN UPPER RIDGE MOVING IN.

EXPECT A COOLER NIGHT TONIGHT WITH THE SFC AND UPPER RIDGE
OVERHEAD...MAKING FOR MOSTLY CLEAR SKIES. LOWS WILL BE IN THE MID
20S TO LOW 30S...COLDEST INTERIOR.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 501 AM EDT THU APR 30 2015

DURING THE LONG TERM...MODELS STILL DEPICT A TRANSITION TO LOWER
AMPLITUDE MORE ZONALLY ORIENTED FLOW IN THE VCNTY OF THE U.S./CANADA
BORDER. DURING THE LAST HALF OF NEXT WEEK...IT APPEARS THERE MAY BE
A MORE PRONOUNCED SPLIT FLOW DEVELOPING AS RIDGE BUILDS IN WRN
CANADA OVERTOP TROFFING OVER THE WRN CONUS. AS A RESULT OF THESE
CHANGES...ABOVE NORMAL TEMPS WILL LIKELY BE THE RULE FROM FRI THRU
MUCH OF NEXT WEEK...THOUGH TEMPS LATE NEXT WEEK WILL DEPEND ON
WHETHER THE UPPER LAKES BECOME MORE INFLUENCED BY THE NRN STREAM
(COOLER DUE TO ERN CANADA TROF THAT DEVELOPS IN RESPONSE TO THE WRN
CANADA RIDGE) OR THE SRN STREAM (WARM DUE TO THE SW FLOW DOWNSTREAM
OF THE WRN CONUS TROF). WHILE THERE WILL BE SOME PCPN CHANCES THRU
THE FIRST HALF OF NEXT WEEK (BEST CHC SUN AFTN/NIGHT)...MEDIUM RANGE
GUIDANCE OVER THE LAST 24HRS STILL PAINTS A PICTURE OF BLO NORMAL
PCPN FOR UPPER MI. THE LAST HALF OF NEXT WEEK APPEARS TO OFFER
DECENT POTENTIAL FOR MUCH NEEDED PCPN ACROSS THE AREA AS PERSISTENT
SOUTHERLY FLOW DOWNSTREAM OF WRN CONUS TROF WILL ALLOW A GOOD SUPPLY
OF GULF MOISTURE TO STREAM N THRU THE PLAINS AND MISSISSIPPI VALLEY.
AS LONG AS THE AFOREMENTIONED NRN STREAM TROF DOES NOT BECOME
DOMINANT AND SUPPRESS MOISTURE AND SRN STREAM SHORTWAVES S OF
HERE...THE PATTERN SHOULD BE SUPPORTIVE OF MUCH NEEDED RAINFALL
ACROSS UPPER MI DURING THE LAST HALF OF NEXT WEEK. WE`LL SEE.

BEGINNING FRI...SHORTWAVE TROF MOVING ACROSS SASKATCHEWAN/MANITOBA
AND THE NRN PLAINS THU NIGHT WILL REACH THE UPPER LAKES LATE FRI. AS
A RESULT...AFTER A SUNNY START TO THE DAY...CLOUDS WILL BE ON THE
INCREASE FROM W TO E FRI AFTN/EVENING. THE SUNNY START WILL HELP
TEMPS RISE INTO THE 60S IN THE INTERIOR FRI...EVEN CLOSE TO 70F AT
SOME LOCATIONS OVER THE W. SHORTWAVE TROF WILL WEAKEN SUBSTANTIALLY
AS IT DRIVES INTO THE MID LEVEL RIDGE THAT WILL BE HELD UP OVER THE
GREAT LAKES BY THE BLOCKY FLOW OVER FAR ERN NAMERICA. GIVEN THE
WEAKENING FORCING...THE LOW-LEVEL REFLECTION OF THE SHORTWAVE TROF
WASHING OUT (WEAKENING CONVERGENCE)...LACK OF MOISTURE INFLOW AND
ANTECEDANT DRY AIR MASS OVER THE AREA...SHRA ASSOCIATED WITH
SHORTWAVE TROF WILL WEAKEN AND PROBABLY MOSTLY DISSIPATE AS THEY
MOVE INTO UPPER MI FRI AFTN AND EVENING. OPTED TO DOWNPLAY PCPN EVEN
MORE FROM PREVIOUS FCST...WITH SCHC POPS ONLY INTO A SMALL AREA OF
FAR WRN UPPER MI AROUND KIWD FRI AFTN...THEN DRY ACROSS THE AREA FRI
NIGHT.

OVER THE WEEKEND...BROAD/LOW AMPLITUDE TROF WILL BE SET UP OVER WRN
CANADA. IT APPEARS SHORTWAVE ENERGY WILL MOVE THRU MANITOBA INTO FAR
NRN ONTARIO SAT...FAR ENOUGH TO THE NW THAT IT SHOULDN`T POSE A RISK
OF PCPN HERE. THAT SAID...A NUMBER OF MODELS ARE SHOWING SOME SPOTTY
PCPN IN THE INTERIOR CNTRL AND E SAT. THIS APPEARS TO BE DUE TO
LEFTOVER MOISTURE FROM THE TROF THAT WASHES OUT OVER THE AREA FRI
NIGHT. THE MODELS GENERATING PCPN ARE VERY LIKELY OVERDONE WITH LOW-
LEVEL MOISTURE...ESPECIALLY SINCE GREEN-UP HASN`T TAKEN OFF ACROSS
THE REGION. THE NAM SHOWS SFC DWPTS UP AROUND 50F WHICH LOOKS WAY
WAY TOO HIGH. THE GFS HAS SFC DWPTS INTO THE MID 40S...AND THAT ALSO
APPEARS A BIT TOO HIGH. RESULT OF THE HIGH DWPTS IS TOO MUCH
INSTABILITY...ESPECIALLY WITH THE NAM. THE GFS IS AT LEAST MORE
REASONABLE WITH MLCAPE NOT CRACKING 100J/KG. WITH DWPTS MORE LIKELY
TO BE IN THE 30S TO LWR 40S AT BEST ON SAT...PLAN TO LEAVE FCST DRY.
IT WILL BE A WARM DAY WITH HIGHS WELL INTO THE 60S TO MID 70S IN THE
INTERIOR...WARMEST W. UNDER WEAK PRES GRADIENT...LAKE BREEZES WILL
KEEP LAKESIDE LOCATIONS COOL IN THE AFTN.

SUN/MON...AS HAS BEEN THE CASE FOR SEVERAL DAYS...MODELS POINT TO
THE LATE WEEKEND TIME FRAME FOR THE BEST CHC OF PCPN. AS WRN CANADA
TROF DRIFTS EASTWARD AND SHORTWAVES MOVE FROM THE ROCKIES/SCNTRL
CANADA TO NRN ONTARIO AND WRN LAKES...COLD FRONT SHOULD PASS ACROSS
UPPER MI SUN NIGHT...PERHAPS ARRIVING OVER WRN UPPER MI AS EARLY AS
SUN AFTN PER FASTER GFS. WILL FOCUS ON SUN AFTN/SUN NIGHT FOR THE
BEST RAIN CHANCES. INSTABILITY AT THAT TIME WILL BE SUFFICIENT TO
SUPPORT POTENTIAL OF SOME TSTMS AS WELL. GIVEN AN OVERALL FASTER
TREND FROM THE MODELS OVER THE LAST DAY OR SO...FRONT WILL BE THRU
THE FCST AREA BY 12Z MON...RESULTING IN A DRY DAY. HOWEVER...WILL
MAINTAIN SCHC POPS IN THE MORNING OVER THE SE IN THE EVENT THE FRONT
IS A LITTLE SLOWER THAN CURRENTLY EXPECTED. SUN WILL BE THE WARMEST
DAY OF THIS FCST PERIOD WITH HIGHS WELL INTO THE 70S OVER MOST OF
THE W HALF OF UPPER MI. S TO SW WINDS OFF LAKE MICHIGAN WILL KEEP
THE E COOLER. IN THE WAKE OF THE FRONT...EXPECT SOME COOLING FOR
MON... MOST NOTABLY NEAR LAKE SUPERIOR.

DRY WEATHER WILL CONTINUE INTO TUE WITH SFC HIGH PRES OVER THE UPPER
LAKES. TEMPS SHOULD BE SIMILAR TO MON.

ON WED...ENERGY SHOULD BE EJECTING NE THRU THE PLAINS DOWNSTREAM OF
THE WRN CONUS TROF. SIMILAR TO RECENT RUNS...00Z GFS/ECMWF/GEM AND A
NUMBER OF GEM ENSEMBLES ALL INDICATE PCPN SPREADING INTO MUCH OF THE
FCST AREA WED. WILL THUS INCLUDE SCHC TO CHC POPS ACROSS THE FCST
AREA.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 100 PM EDT THU APR 30 2015

KIWD...VFR CONDITIONS WILL PERSIST THROUGH THIS TAF PERIOD.

KCMX...CONTINUED UPSLOPE AND REMAINING LOW LEVEL MOISTURE HAS
DELAYED THE EROSION OF LOW LEVEL CLOUD COVER ACROSS THE CMX TAF SITE.
WINDS ARE EXPECTED TO DECREASE THIS AFTERNOON AS A RIDGE OF HIGH
PRESSURE AND DRIER AIR BEGINS TO SLIDE ACROSS THE AREA. CONDITIONS
ARE EXPECTED TO IMPROVE TO VFR BY 19Z AND THEN REMAIN VFR THROUGH
THE REMAINDER OF THE TAF PERIOD.

KSAW...IMPROVEMENT WILL BE MORE GRADUAL ACROSS CENTRAL PORTIONS OF
THE U.P. AS UPSLOPE FLOW AND CONTINUED LOW LEVEL MOISTURE CONTINUE
INTO THE MID TO LATE AFTERNOON HOURS. THE CLOUDS MAY BEGIN TO SLOWLY
MIX OUT BY MID AFTERNOON...ALLOWING FOR SOME IMPROVEMENT...BUT VFR
CONDITIONS WILL LIKELY HOLD OFF UNTIL THE LATE AFTERNOON
HOURS...AROUND 22Z TO 23Z.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 352 AM EDT THU APR 30 2015

A HIGH PRESSURE SYSTEM WILL BUILD OVER HUDSON BAY AND EXTEND A RIDGE
S INTO THE WRN GREAT TODAY. WINDS WILL SLOWLY DIMINISH TODAY...WITH
LIGHT WINDS EXPECTED TONIGHT. WITH WEAK PRESSURE GRADIENT OVER THE
UPPER LAKES FRI THRU SAT...WINDS SHOULD BE LIGHT...MOSTLY UNDER
15KT. A LOW PRESSURE TROUGH APPROACHES FROM THE WEST LATE SAT
NIGHT/SUN BUT IT LOOKS WEAK AS WINDS SHOULD REMAIN BELOW 20 KTS. THE
TROUGH WILL CROSS THE AREA ON SUN...WITH A HIGH SETTLING IN ON
TUESDAY. WINDS WILL REMAIN RELATIVELY LIGHT.
&&

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

$$

SHORT TERM...TITUS
LONG TERM...ROLFSON
AVIATION...KEC
MARINE...TITUS


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