Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 281959
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
359 PM EDT TUE APR 28 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 359 PM EDT TUE APR 28 2015

WATER VAPOR IMAGERY AND RAP ANALYSIS INDICATE UPSTREAM SHORTWAVE
ENERGY SPLITTING WITH ONE SHORTWAVE DIVING SE THROUGH CENTRAL MN AND
ANOTHER MORE SHEARED OUT SHORTWAVE MOVING EAST THROUGH NRN MN AS IT
APPROACHES LAKE SUPERIOR. THE ENERGY SPLIT RESULTS IN WEAKENING
DYNAMICS OUT AHEAD OF SHORTWAVE TROUGH AS DEPICTED BY WEAKENING MID-
LVL Q-VECT CONVERGENCE. AND THIS PARTLY EXPLAINS WHY LINE OF SHRA
APPROACHING FM THE WEST IS ALSO WEAKENING AND BREAKING APART AS
NOTED ON REGIONAL RADAR LOOP.

TONIGHT...SHORTWAVE TROUGH APPROACHING FROM MN IS EXPECTED TO CROSS
LAKE SUPERIOR TONIGHT. MODEL Q-VECT CONV INDICATES BEST Q-VECT CONV
SPLITTING NORTH AND SOUTH OF CWA SO WOULD EXPECT WEAKENING TREND TO
CONTINUE WITH APPROACHING LINE OF SHRA THIS EVENING. EXPECT THE DRY
FCST TO CONTINUE ESPECIALLY GIVEN THE DRY AIRMASS IN PLACE.
SECONDARY SHORTWAVE NOW MOVING NW ONTARIO WL THEN BEGIN DIGGING MORE
SHARPLY TO THE S TONIGHT WITH MODELS SUGGESTING A MID LEVEL LOW
BEGINNING TO CLOSE OFF JUST N OF LAKE SUPERIOR LATE TONIGHT. THIS
SHOULD SUPPORT AN EXPANSION OF PCPN N AND E OF LAKE SUPERIOR
TONIGHT...CLOSER TO GREATEST HEIGHT FALLS. PCPN MAY TRY TO DEVELOP S
INTO ERN UPPER MI...BUT LACK OF DEEP FORCING SUGGESTS MAINLY DRY
WEATHER SHOULD CONTINUE THRU THE NIGHT.  EXPECT LOWS TONIGHT IN THE
30S UNDER PARTLY TO MOSTLY CLOUDY SKIES.

WEDNESDAY...CLOSED LOW AND ASSOC MID-LVL TROF CONTINUES TO DESCEND
SOUTH OVER ERN UPPER MI. 12Z NAM SOUNDING FOR KERY SHOWS SHALLOW LOW-
LVL MOISTURE EXTENDING TO 7-8 KFT BUT REMAINING BELOW -10C ISOTHERM.
WOULD EXPECT ONLY SPRINKLES AT BEST FOR ERN COUNTIES (POSSIBLY AIDED
BY UPSLOPE NRLY FLOW) AS BEST SYNOPTIC FORCING/Q-VECT CONV AND
DEEPER MOISTURE REMAINS EAST OF FCST AREA. N WINDS OF 10-15MPH
GUSTING TO 20MPH WILL KEEP LAKE SUPERIOR SHORELINE LOCATIONS COOL
WITH HIGHS ONLY REACHING THE 40S. FARTHER INLAND HIGHS COULD
REACH INTO THE 50S.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 316 PM EDT TUE APR 28 2015

OVERALL...LITTLE CHANGES IN THE FORECAST THOUGHTS OVER THE LAST
24HRS...WITH THE REGION SEEING LIMITED PRECIPITATION CHANCES
THROUGH SUNDAY AND A TRANSITION TO ABOVE NORMAL TEMPERATURES. THIS
TRANSITION WILL BE LED BY AN UPPER RIDGE THAT WILL BUILD OVER THE
GREAT LAKES REGION ON THURSDAY NIGHT WHILE AN UPPER TROUGH BECOMES
ESTABLISHED OVER WESTERN CANADA. THIS WILL PLACE THE AREA UNDER
ZONAL FLOW FRIDAY INTO THE WEEKEND...WITH WEAK SHORTWAVES AND
SURFACE TROUGHS LEADING TO LOW CHANCES FOR PRECIPITATION.

BEFORE THAT UPPER RIDGE MOVES INTO THE AREA ON THURSDAY NIGHT...THE
START OF THE LONG TERM FORECAST WILL SEE A STRONG SHORTWAVE DIVING
SOUTH-SOUTHEAST ACROSS THE GREAT LAKES REGION. THE 700-500MB LOW
ASSOCIATED WITH THIS FEATURE WILL TRACK ACROSS EASTERN UPPER
MICHIGAN AND SHOULD KEEP ANY SHOWERS ASSOCIATED WITH THE SHORTWAVE
TO THE EAST OF A LINE FROM MUNISING TO MANISTIQUE. IT DID APPEAR
THAT THERE MAY BE ENOUGH NORTHERLY FLOW UPSLOPE HELP TO PRODUCE A
FEW SHOWERS/DRIZZLE OVER THE NORTH CENTRAL (NOT COLD ENOUGH FOR ICE
CRYSTALS AND SNOW)...SO DID ADD A MENTION OF RAIN TO THAT AREA FOR
WED NIGHT INTO THURS MORNING. THE DISTURBANCE WILL QUICKLY MOVE
SOUTH OF THE AREA WEDNESDAY NIGHT INTO THURSDAY...ALLOWING THE UPPER
RIDGE TO BUILD EAST INTO THE UPPER GREAT LAKES REGION FROM THE
NORTHERN PLAINS AND SOUTHERN CANADA. THAT WILL LEAD TO DRIER AIR
WORKING INTO THE AREA AND IN TURN DECREASING CLOUDS FROM WEST TO
EAST ON THURSDAY. EXPECT TEMPERATURES TO STILL REMAIN BELOW
NORMAL...ESPECIALLY OVER THE NORTH WITH THE COOL AIR COMING OFF LAKE
SUPERIOR.

FRIDAY WILL FEATURE A NICE START TO THE DAY IN THE U.P. WITH SUNNY
CONDITIONS ALLOWING TEMPERATURES TO WARM INTO THE 50S AND 60S. THE
NEXT DISTURBANCE (SLIDING EAST ALONG THE US/CANADIAN BORDER ON THE
LEADING EDGE OF THE UPPER TROUGH BECOMING ESTABLISHED IN WESTERN
CANADA WILL MOVE INTO WESTERN UPPER MICHIGAN IN THE AFTERNOON AND
THEN THE REST OF THE CWA THROUGH EARLY EVENING. THIS WILL LEAD TO
INCREASING CLOUDS DURING THE AFTERNOON. LIKE THE SHORTWAVE AND FRONT
THAT WILL BE MOVING THROUGH THE AREA THIS AFTERNOON/TONIGHT...IT
WILL BE RUNNING INTO EXISTING DRY AIR AND ALSO BECOMING SHEARED OUT.
THUS...EXPECT THE SYSTEM/PRECIPITATION TO DIMINISH AS IT SHIFTS INTO
THE WESTERN U.P. WILL CONTINUE TO SHOW SLIGHT CHANCE POPS OVER THE
WEST IN THE AFTERNOON AND THEN DIMINISHING AS IT SHIFTS EAST OVER
THE REST OF THE CWA IN THE EVENING.

BEHIND THAT DISTURBANCE...ZONAL FLOW BECOMES ESTABLISHED OVER THE
NORTHERN CONSUS AND EXPECT THAT TO LEAD TO ABOVE NORMAL
TEMPERATURES FOR MUCH OF THE CWA. ECMWF HAS BEEN CONSISTENT (OVER
THE LAST 6-8 RUNS) WITH HIGHS IN THE UPPER 60S TO LOWER 70S ON
SATURDAY AT KSAW/KIWD/KIMT AND A FEW DEGREES WARMER FOR SUNDAY.
THUS...WILL TREND THEIR FORECASTS UP TOWARDS THAT IDEA FOR BOTH OF
THOSE DAYS. WITH WINDS GENERALLY LIGHT...SHOULD SEE LAKE BREEZES
DEVELOP ON SATURDAY. WILL NEED TO KEEP AN EYE ON A DISTURBANCE
FORECAST TO TRACK EAST OUT OF THE CENTRAL ROCKIES ON SATURDAY. AT
THIS POINT...IT LOOKS TO STAY TO THE SOUTH OF THE AREA...BUT THERE
HAVE BEEN SOME INDICATIONS THAT IT MAY SLIDE NORTH AND AFFECT THE
AREA ON SUNDAY. OTHERWISE...THE DEPARTING SURFACE RIDGE TO THE EAST
WILL LEAD TO LIGHT SOUTHERLY FLOW DEVELOPING ON SUNDAY.

THE BEST OPPORTUNITY FOR RAIN WILL COME SUNDAY NIGHT INTO MONDAY
MORNING...AS THE UPPER TROUGH OVER THE CANADIAN ROCKIES SHIFTS EAST
AND INTERACTS WITH WEAK DISTURBANCES LIFTING NORTHEAST OUT OF THE
CENTRAL/SOUTHERN ROCKIES. WILL FOCUS ON THIS TIME FOR THE BEST RAIN
CHANCES AND TREND POPS UP BEFORE DIMINISHING THEM ON MONDAY
AFTERNOON AS THE WAVES DEPART. STILL COULD SEE SOME SHOWER LINGERING
INTO MONDAY NIGHT OR EVEN TUESDAY MORNING DEPENDING ON HOW QUICKLY
THE UPPER TROUGH AXIS DEPARTS.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 131 PM EDT TUE APR 28 2015

ALTHOUGH A WEAK LOW PRES TROF WILL MOVE ACROSS THE AREA LATE THIS
AFTN AND EVENING...DRY AIR WILL PERSIST IN THE LOWER LEVELS...
ALLOWING VFR CONDITIONS TO PREVAIL THRU THE FCST PERIOD AT
KIWD/KCMX/KSAW. NORTH WINDS WILL LIKELY GUST OVER 15 KT AT KCMX AND
KSAW ON WED AHEAD OF HIGH PRES BUILDING DOWN FROM HUDSON BAY.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 359 PM EDT TUE APR 28 2015

WINDS WILL BE LIGHT...UNDER 15KT...AS A VERY WEAK LOW PRES TROF
PASSES THE AREA THIS EVENING. IN ITS WAKE... ANOTHER HIGH PRES WILL
BUILD OVER HUDSON BAY AND EXTEND A RIDGE S INTO THE WRN GREAT LAKES
WED/THU. AS THE HIGH BEGINS RIDGING S INTO THE UPPER LAKES LATE
TONIGHT/WED...NNW WINDS OVER ERN LAKE SUPERIOR WILL LIKELY GUST TO
AROUND 20KT. WINDS WILL BE LIGHTER OVER THE W. WITH WEAK PRES
GRADIENT OVER THE UPPER LAKES THU THRU SAT...WINDS SHOULD BE
LIGHT...MOSTLY UNDER 15KT. A LOW PRES TROUGH APPROACHES FROM THE
WEST LATE SAT NIGHT/SUN BUT IT LOOKS WEAK AS WINDS SHOULD REMAIN BLO
20 KTS.
&&

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

$$

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



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