Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 272013
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
413 PM EDT WED MAY 27 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 340 AM EDT WED MAY 27 2015

A SHORTWAVE AND ASSOCIATED SFC LOW ARE DRIVING RAIN SHOWERS OVER
MAINLY WESTERN AND CENTRAL UPPER MI EARLY THIS MORNING. THIS AXIS OF
GREATEST PRECIP AMOUNTS/COVERAGE WILL SHIFT E OVER PRIMARILY THE ERN
U.P. THIS MORNING AND WILL EXIT E OF THE CWA BY 21Z TODAY.

MEANWHILE...A WEAKER SHORTWAVE CURRENTLY OVER SRN SASKATCHEWAN MOVE
ACROSS WRN AND CENTRAL UPPER MI LATE THIS AFTERNOON INTO THIS
EVENING. THE GREATEST FORECAST UNCERTAINTY IN THE SHORT TERM IS
RELATED TO CONVECTIVE POTENTIAL WITH THIS SECOND SHORTWAVE.
CONVECTIVE POTENTIAL WILL RELY HEAVILY ON HOW FAST PRECIP AND CLOUD
COVER MOVE OUT TODAY...DETERMINING INSTABILITY LEVELS. ALSO IN
QUESTION IS THE EXACT TRACK OF THE SHORTWAVE...WHICH IS SHOWN
HEADING S OF THE CWA BY A COUPLE MODELS. AT THIS POINT...IT APPEARS
THERE WILL BE CONVECTION FIRING ALONG THE LAKE BREEZE BOUNDARIES
OVER NCENTRAL UPPER MI LATE THIS AFTERNOON AND THIS EVENING AND
POSSIBLY ALONG THE WI BORDER AS WELL. AS FOR STRENGTH OF THE
CONVECTION...CONFIDENCE IS QUITE LOW. MODELS RANGE FROM A FEW
HUNDRED J/KG OF CAPE TO 1500 J/KG. ALSO...MODELS INDICATE THAT
EFFECTIVE SHEAR WILL INCREASE FROM VERY MARGINAL LEVELS EARLY TODAY
TO 30-35KTS AROUND EXPECTED TIME OF CONVECTIVE INITIATION (21Z) AS
THE SHORTWAVE MOVES INTO THE AREA. ADDITIONALLY...WNW FLOW IS THE
FAVORED FLOW FOR STRONGER CONVECTION OVER THE NCENTRAL. CERTAINLY A
CONDITIONAL AND VERY UNCERTAIN STRONG/SEVERE THREAT. WILL NOT HYPE
THE THREAT UP MUCH RIGHT NOW...ESPECIALLY GIVEN THAT IT WILL BE
FAIRLY LATE IN THE DAY...MORE INTO THE EVENING TIME FRAME...SO THE
DAY SHIFT WILL HAVE PLENTY OF TIME TO MONITOR TRENDS AND MAKE
REFINEMENTS. OTHERWISE...EXPECT HIGH TEMPS TODAY IN THE 60S E HALF
TO 70S W HALF...LOCALLY COOLER NEAR LAKE SUPERIOR.

REMAINING CONVECTION (IF ANY) WILL DISSIPATE TONIGHT AS THE
SHORTWAVE MOVES OUT AND INSTABILITY DIMINISHES. SKIES WILL BE
CLEARING INITIALLY...BUT CLOUDS WILL DEVELOP NEAR LAKE SUPERIOR AS
FLOW BECOMES NELY LATER IN THE NIGHT. LOWS WILL MAINLY BE IN THE
40S...WITH LOWS AROUND 50 OVER THE SCENTRAL.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 412 PM EDT WED MAY 27 2015

PRIMARY WEATHER ISSUES IN THE LONG TERM ARE TSRA STRENGTH ON FRIDAY
AND MIN TEMPS/FREEZE POTENTIAL FOR SATURDAY NIGHT AND SUNDAY NIGHT.

SHORTWAVE RIDGE IS OVER UPPER GREAT LAKES ON THURSDAY EVENING WITH
BROAD TROUGH FM CNTRL CANADA BACK OVER THE WESTERN CONUS. ANY ISOLD
SHRA/TSRA ON THURSDAY AFTN SHOULD FADE AWAY WITH LOSS OF DAYTIME
HEATING AND MINUS ADDITIONAL LARGER SCALE LIFTING MECHANISM. ANOTHER
SMALL CHANCE OF SHRA/TSRA LATER AT NIGHT OVER THE WEST AHEAD OF
BETTER MOISTURE TRANSPORT OUT AHEAD OF LOW PRESSURE AND COLD FRONT
MOVING ACROSS THE NORTHERN PLAINS. SOME HINT OF WEAKER SHORTWAVE
TIED TO THAT MOISTURE TRANSPORT. IF THAT OCCURS...BETTER CHANCE FOR
ORGANIZED SHRA AND POSSIBLE TSRA LATE THU NIGHT INTO FRIDAY MORNING.

AS CENTRAL CANADA TROUGH ALOFT DROPS ACROSS MANITOBA AND NORTHERN
ONTARIO ON FRIDAY ASSOCIATED LOW PRESSURE AND SFC COLD FRONT MOVES
FROM NORTHERN PLAINS TO THE UPPER GREAT LAKES. DECENT AGREEMENT FM
THE MODELS THAT FROPA OCCURS FRIDAY AFTN. MAIN QUESTION REMAINS IN
HOW MUCH INSTABILITY BUILDS UP AHEAD OF THE FRONT...AND WOULD
CERTAINLY BE AFFECTED BY ANY SHRA/TSRA AROUND DURING THE MORNING
HOURS. OVERALL THERE IS DECENT AGREEMENT THAT MLCAPES WILL BE AT
LEAST 500J/KG AND MAY BE OVER 1000 J/KG BY TIME FRONT WORKS ACROSS
IN THE AFTN. GREATEST INSTABILITY IS LOCATED OVER WI...BUT IS
FORECAST TO EXPAND OVER PORTIONS OF CNTRL UPR MICHIGAN AHEAD OF THE
FRONT. DEEP LAYER SHEAR UP TO 35 KTS WOULD BE FAVORABLE FOR
ORGANIZED STORMS...BUT POTENTIAL WILL BE HELD DOWN IF MORE
WIDESPREAD SHRA AND TSRA ARE AROUND EARLIER IN THE DAY. MOISTURE
AVAILABILITY NOT AN ISSUE AS PERSISTENT H85-H7 MOISTURE TRANSPORT
BOOSTS PWATS OVER 1.5 INCHES ALONG AND AHEAD OF THE FRONT. FAIR TO
SAY IF THERE IS AT LEAST SOME INSOLATION ON FRIDAY...THERE WOULD BE
RISK OF AT LEAST STRONG STORMS DURING THE AFTN. SPC DAY3 RISK HAS
MARGINAL CATEGORY MAINLY SOUTH OF HERE INTO WHERE BETTER CHANCE OF
HIGHER INSTABILITY RESIDES. FRONT MOVES ACROSS ALL OF UPR MICHIGAN
AFTER MIDNIGHT FRIDAY NIGHT. IT WILL PROBABLY TAKE UNTIL THE FRONT
HAS EXITED BEFORE CHANCES OF RAIN ARE ELIMINATED DUE TO DEEP
MOISTURE PERSISTING EVEN BEHIND THE SFC FRONT AND POSSIBILITY OF
SHORTWAVES WORKING THROUGH ON EDGE OF LARGE SCALE TROUGH. POPS
HIGHEST FRIDAY WITH THIS FROPA.

CONFLUENCE ALOFT ON WESTERN EDGE OF TROUGH MOVING ACROSS NORTHERN
ONTARIO AND QUEBEC LEADS TO LARGE HIGH PRESSURE BUILDING IN ON
SATURDAY. CHILLY DAY FOR LATE MAY STANDARDS ON SATURDAY AS TEMPS
EVEN INLAND TOWARD WI BORDER MAY ONLY STRUGGLE INTO THE 50S DESPITE
GOOD DEAL OF SUNSHINE. GRADIENT ONSHORE WINDS NEAR LK SUPERIOR WILL
KEEP TEMPS THERE IN THE 40S. AIRMASS QUITE DRY WITH PWATS DROPPING
TO 0.25-0.35 INCHES BY SATURDAY NIGHT. LIGHT WINDS/CLEAR SKIES AND
DRY AIRMASS POINT TO STRONG RADIATIONAL COOLING AND WITH DWPNTS ON
SATURDAY BLO 30F...A FREEZE IS LIKELY ON SATURDAY NIGHT. LACK OF ANY
ONSHORE FLOW LATER SATURDAY NIGHT FAVORS EVEN SHORELINE AREAS NEAR
LK SUPERIOR AND MOST OF LK MICHIGAN FOR MIN TEMPS AT LEAST IN THE
LOWER 30S WITH STRONG FROST POSSIBILITY. WEAK EASTERLY WINDS ON
SOUTHERLY EDGE OF SFC HIGH COULD KEEP BAY OF GREEN BAY SHORE IN FAR
SCNTRL WITH THE WARMEST TEMPS OVER THE CWA. ANOTHER CHILLY DAY FOR
SUNDAY UNDER MOSTLY SUNNY SKIES. INLAND TEMPS NEAR 60 DEGREES WHICH
IS OVER 10 DEGREES BLO NORMAL. TEMPS ALONG LK SUPERIOR WILL BE
MAINLY IN THE 40S OR 50S. WENT ON LOW SIDE FOR TEMPS SUNDAY NIGHT
AND INCLUDED FROST MENTION AGAIN. SOME BIAS CORRECTED GUIDANCE
INDICATED MINS BACK TO AROUND 32 DEGREES WHICH SEEMS REASONABLE
AS RIDGE AND DRY AIRMASS LINGERS...ESPECIALLY CNTRAL AND EAST.

REST OF EXTENDED FEATURES A WARMING TREND. UPPER LEVEL FLOW FLATTENS
OUT IN WAKE OF THE TROUGH THIS WEEKEND. HIGH AT THE SFC SLOWLY MOVES
OFF TO THE EAST OVER NEW ENGLAND AND MID ATLANTIC PUTTING PLAINS AND
GREAT LAKES WITHIN RETURN FLOW. H85 TEMPS AS EARLY AS TUESDAY RISE
TO 14C...WHICH WOULD YIELD HIGHS WELL INTO THE 70S INLAND FROM THE
GREAT LAKES. MAY SEE SOME MID CLOUDS SPILL ACROSS UPR LAKES ON
TUESDAY DUE TO WARM AIR ADVECTION H85-H7. PROBABLY NOT MUCH RISK OF
SHRA THOUGH AS FORCING AND MOISTURE IS MARGINAL AT BEST. MAYBE BETTER
CHANCE OF SHRA/TSRA ON WEDNESDAY AS TROUGH ALOFT HEADS ACROSS
WESTERN CONUS. BETTER CHANCES PROBABLY STAY WEST YET CLOSER TO THE
SFC LOW OVER THE NORTHERN PLAINS. AS LONG AS SYSTEM DOES NOT SPEED
UP TO THE EAST...GOOD CHANCE THAT TEMPS MAY TOP OUT AROUND 80
DEGREES ON WEDNESDAY.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 158 PM EDT WED MAY 27 2015

EXPECT VFR CONDITIONS THROUGH THE FORECAST PERIOD. WITH ONLY A SMALL
CHANCE OF SHRA/TSRA AND LOW CONFIDENCE THAT ANY WILL AFFECT THE TAF
SITES THIS AFTERNOON...NO MENTION WAS INCLUDED AT THIS TIME. UPSLOPE
ERLY FLOW DEVELOPS AT CMX TONIGHT BUT EXPECT ENOUGH DRYING TO
LIMIT POTENTIAL FOR FOG OR LOW CLOUDS.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 340 AM EDT WED MAY 27 2015

WINDS ARE EXPECTED TO STAY AT OR BELOW 20 KNOTS FOR MOST OF THIS
FORECAST PERIOD WITH THE EXCEPTION OF FRI NIGHT INTO EARLY SATURDAY
WHERE THEY WILL BE UP TO 25 KNOTS ACROSS EASTERN LAKE SUPERIOR. FOG
WILL LINGER THROUGH INTO TONIGHT AND WILL BE DENSE AT TIMES.
ADDITIONAL FOG IS EXPECTED TO DEVELOP THURSDAY NIGHT AND FRIDAY
AHEAD OF THE NEXT LOW AND ASSOCIATED COLD FRONT.
&&

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

$$

SHORT TERM...TITUS
LONG TERM...JLA
AVIATION...JLB
MARINE...TITUS


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