000
FXUS63 KMQT 171037
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
637 AM EDT FRI MAY 17 2013

.UPDATE...
ISSUED AT 633 AM EDT FRI MAY 17 2013

BAND OF ISOLD SHRA/SPRINKLES EDGING OUT OF MINNESOTA ONTO WESTERN LK
SUPERIOR. H7 FGEN/MOISTURE BAND SUPPORTING THESE COULD CLIP KEWEENAW
SO HAVE INCLUDED SOME SPRINKLES FOR THE MORNING. INCREASED SKY COVER
FOR ALL BUT FAR EAST AS 12-15KFT DECK OF CLOUDS HAS SOLIDIFIED OVER
LAST COUPLE HOURS. WITH MORE CLOUD COVER...TEMPS HAVE BECOME STEADY
OR EVEN SLOWLY RISING. ADJUSTED TEMPS NEXT FEW HOURS. THINNING OUT OF
CLOUDS OVER NORTH STILL POSSIBLE BY AFTN WITH LOSS OF DIVERGENCE
ALOFT. FARTHER SOUTH THE SHOWERS LIFTING NORTH THROUGH WI...AS FAR
NORTH AS KAUW...STILL ON TRACK TO AFFECT VCNTY OF MEMOMINEE AFTER
17Z.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 446 AM EDT FRI MAY 17 2013

IN CONFLUENT FLOW PATTERN ALOFT EXPECT HIGH PRESSURE TO EXPAND FROM
NORTHERN ONTARIO ACROSS GREAT LAKES TODAY. LIGHT WINDS OVER FAR EAST
ALONG THE RIDGE AXIS AND CLEARER SKIES HAVE ALLOWED TEMPS TO FALL
BLO 30 AT A FEW OF THE FIRE WX RAWS SITES. WARM FRONT STAYS WELL TO
SOUTHWEST OF UPR MICHIGAN TODAY...CURRENTLY FROM CENTRAL PLAINS INTO
NORTHERN OHIO VALLEY...ONLY ADVANCING INTO SOUTHERN MINNESOTA AND
SOUTHERN WISCONSIN BY THIS EVENING. A LOT OF MID CLOUDS OVER THE
UPPER LAKES REGION THIS MORNING. REGIONAL RADAR LOOP SHOWS MULTIPLE
RIBBONS OF SHRA ACROSS NORTHERN MINNESOTA AND ALSO AS FAR NORTH AS
CENTRAL WISCONSIN. BOTH AREAS OF SHOWERS ARE SUPPORTED BY MID-LEVEL
FRONTOGENESIS AND H85-H7 MOISTURE ADVECTION. MORE ORGANIZED CLUSTER
OF SHRA AND NMRS TSRA OCCURRING OVER NORTHERN IA INTO FAR SOUTHERN
MINNESOTA ALONG H85 WARM FRONT/H95 MOISTURE CONVERGENCE AND ON EDGE
OF 1-6KM MUCAPE GRADIENT.

PRIMARY QUESTION IS RAIN POTENTIAL/COVERAGE THROUGH TONIGHT. TO SUM
UP HAVE WENT WITH DRIER FCST FARTHER NORTH INTO UPR MICHIGAN
COMPARED TO WHAT MANY MODELS SHOW. THINKING THAT MAJORITY OF MODELS
ARE OVERDONE WITH PRECIP GIVEN BUILDING SFC-H85 HIGH PRESSURE RIDGE
FROM NORTHERN ONTARIO INTO THE LOWER GREAT LAKES AND LACK OF STRONG
MOISTURE ADVECTION AS FAR NORTH AS UPR MICHIGAN. SHRA OVR NORTHERN
MINNESOTA EXPECTED TO DISSIPATE AS RIGHT ENTRANCE REGION OF JET OVER
ONTARIO FADES THROUGH 15Z. ISLE ROYALE COULD STILL GET CLIPPED WITH
ISOLD SHRA...REST OF WESTERN CWA SHOULD STAY DRY. MEANWHILE...H7
MOISTURE TRANSPORT MARKING EDGE OF SHRA OVER CNTRL WISCONSIN PRETTY
WELL RIGHT NOW. MOISTURE ADVECTION AT H7 AND H8-H7 FRONTOGENESIS IS
FORECAST TO IMPACT FAR SCNTRL CWA BY LATE MORNING AND REST OF THE
DAY. HAVE BROUGHT LOW CHANCE POPS INTO MENOMINEE COUNTY...BUT SHOULD
BE SHARP CUTOFF FARTHER NORTH FOR PRECIP GIVEN DOWNWARD MOTION ON
DECENDING BRANCH OF THE MID-LEVEL FRONTOGENESIS. NAM/GEM-REGIONAL
PROBABLY TOO DRY TODAY OVER THE SOUTHERN CWA...BUT SEEM BETTER FIT
COMPARED TO GFS/ECMWF. SHOULD NOTE THAT EVEN THESE MODELS HAVE
TRENDED FARTHER SOUTH WITH AXIS OF QPF COMPARED TO MODEL RUNS FROM
THURSDAY.

ELSEWHERE...SCT-BKN MID CLOUDS SHOULD BE THE STORY ALONG WITH LGT
EASTERLY SFC WINDS WITH ORIGIN OUT OF SFC HIGH AND WELL TO NORTH OF
THE SFC WARM FRONT. THINNING OF MID CLOUDS OVERHEAD MAY OCCUR AS
RIGHT ENTRANCE REGION FORCING FROM JET OVER ONTARIO DIMINISHES.
TEMPS SHOULD HAVE NON-UNIFORM GRADIENTS DUE TO CLOUDS AND SFC WIND
TRAJECTORIES. WARMEST READINGS AROUND 70 DEGREES IN THE FAR EAST.
COOLEST READINGS IN 50S ALONG LK SUPERIOR WITH PREVAILING ONSHORE
FLOW. MAY ALSO SEE COOLER POCKET OF TEMPS SET UP ALONG WI BORDER DUE
TO THICKER CLOUD COVER AND POTENTIAL PRECIP. UNLIKE LAST FEW
DAYS...H9-H85 LIMITED DRY AIR IN THE H9-H85 LAYER SHOULD PROHIBIT
DEEP MIXING AND VERY LOW HUMIDITIES.

TONIGHT...LARGE SCALE FORCING CHANGES START TO INCREASE CHANCES FOR
PRECIP TO MAKE IT INTO AT LEAST MORE OF UPR MICHIGAN. UPPER LEVEL
TROUGH MOVES INTO NORTHERN ROCKIES WITH SFC-H85 LOWS BECOMING MORE
ORGANIZED OVER NORTHERN PLAINS. WINDS BECOME MORE SOUTHERLY OVER
UPPER MISSISSIPPI RIVER VALLEY IN RESPONSE. H85 BAROCLINIC ZONE
LIFTS TOWARD WESTERN LK SUPERIOR AND NORTHERN WISCONSIN THROUGH THE
NIGHT. ISENTROPIC ASCENT ALONG THE BOUNDARY SUPPORTS CHANCES OF SHRA
INCREASING. SHARPEST MOISTURE TRANSPORT INTO THE H85 BOUNDARY IS
OVER NORTHERN MINNESOTA AND INTO WESTERN LK SUPERIOR...WITH A
TAPERING OFF FARTHER EAST. NOT MUCH H7 MOISTURE ADVECTION FARTHER
EAST EITHER. REALLY PREFER THE GEM-REGIONAL/NAM/NCEP WRF IDEA FOR
CONVECTION TONIGHT...FAVORING MAJORITY OF SHRA/TSRA OVER NORTHERN
MINNESOTA INTO SOUTHWEST UPR MICHIGAN. EDGE OF CAPE GRADIENT ALSO
SUPPORTS BETTER TSRA POTENTIAL INTO SW UPR MICHIGAN FROM LATE
EVENING ONWARD. BY LATE TONIGHT...MAJORITY OF MODELS SHOVE THE
CONVECTION...OR AT LEAST REMNANTS OF IT...INTO CNTRL UPR MICHIGAN.
SUPPOSE THIS MAY OCCUR DO TO LEAD SHORTWAVE PRESSING ACROSS NORTHERN
MINNESOTA AND H7 MOISTURE TRANSPORT VECTORS TURNING MORE WEST TO
EAST. NOT SOLD ON A LOT OF PRECIP MAKING IT WELL TO EAST OF GRADIENT
OF INSTABILITY ALOFT...SO JUST USED SLIGHT CHANCE POPS OTHER THAN
OVER FAR WESTERN CWA. MINS TONIGHT HELD UP BY THICKENING CLOUDS AND
PRECIP. TEMPS OVER INTERIOR EAST MAY DROP INTO 30S...BUT NOT AS COOL
AS EARLY THIS MORNING. 40S TO AROUND 50 FOR MINS EVERYWHERE ELSE.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 446 AM EDT FRI MAY 17 2013

NAM SHOWS A 500 MB RIDGE OVER THE UPPER GREAT LAKES 12Z SAT WITH
TROUGHING IN THE ROCKY MOUNTAINS. THE RIDGE REMAINS 12Z SUN WITH A
SHORTWAVE ON THE WESTERN SIDE IN THE DAKOTAS. TROUGHING THEN MOVES
IN THE NORTHERN PLAINS WITH A CLOSED LOW 12Z MON. NAM SHOWS SOME
DEEPER MOISTURE AND Q-VECTOR CONVERGENCE REMAINING OVER THE AREA 12Z
SAT ONWARD.

DID MAKE A MAJOR CHANGE TO THE GOING FORECAST AND WENT DRIER OVER
THE EASTERN HALF OF THE CWA THROUGH SUN NIGHT. AM FINDING IT HARD TO
BELIEVE WITH THE SLOW MOVEMENT OF THE SYSTEM TO THE WEST...BUILDING
UPPER RIDGE TO THE EAST AND A SFC HIGH PRESSURE SYSTEM BRINGING IN
DRY EAST TO SOUTHEAST FLOW...THAT PCPN WOULD BE AS WIDESPREAD AS IT
IS IN THE ECMWF...NAM AND GFS MODELS AND THINK THEY ARE ALL OVERDONE
WITH HIGHER SFC DEW POINTS BEING OVERFORECASTED WHICH HAS BEEN THE
CASE FOR THE PAST SEVERAL WEEKS. WITH HIGHER DEW POINTS BEING
FORECASTED THAN WHAT HAS OCCURRED...THIS WOULD CAUSE MORE WIDESPREAD
QPF THAN WHAT IS ACTUALLY OCCURRING DUE TO CONVECTIVE PARAMETERS
BEING ACTIVATED IN THE MODELS. WITH THIS IN MIND...WILL GO WITH A
DRIER SCENARIO AND CUT POPS BACK WITH CHANCE POPS OVER THE WEST ONLY
THROUGH SUNDAY NIGHT. OTHERWISE...DID NOT MAKE TOO MANY CHANGES TO
THE GOING FORECAST.

IN THE EXTENDED...GFS AND ECMWF SHOW A 500 MB CLOSED LOW OVER THE
NORTHERN PLAINS 12Z MON WITH A RIDGE OVER THE EASTERN U.S. AND
TROUGHING ACROSS THE PLAINS. PATTERN CHANGES VERY LITTLE FOR 12Z TUE
WITH A SLIGHT EASTWARD MOVEMENT 12Z WED INTO THE UPPER MISSISSIPPI
RIVER VALLEY. THIS LOW AND TROUGH MOVE INTO THE UPPER GREAT LAKES
12Z THU. ONE THING WITH THIS PATTERN IS IT WILL BE SLOW TO PROGRESS
EASTWARD. LOOKS LIKE A DECENT CHANCE FOR WIDESPREAD RAIN STARTING
MON AND LASTING INTO WED AS THE TROUGH KICKS OUT. ON THU...DRIER AIR
STARTS TO WORK IN AS A COLD FRONT HEADS SOUTH WED NIGHT INTO THU AND
POPS SHOULD BE LOWER BY THEN. SHOULD ALSO BE A COOLING TREND THIS
FORECAST PERIOD WITH TEMPERATURES COOLING TO BELOW NORMAL STARTING
TUE ONWARD.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 142 AM EDT FRI MAY 17 2013

ALTHOUGH HI CLDS WL BE ON THE INCREASE THRU TODAY...EXPECT VFR
CONDITIONS TO PREVAIL THRU THIS FCST PERIOD WITH DRY E WIND OUT OF
HUDSON BAY HI PRES. IF THIS HI RETREATS...SOME -SHRA MAY IMPACT IWD
THIS EVNG. BUT MENTIONED ONLY VCSH ATTM GIVEN LIKELY PERSISTENCE OF
DRY AIR ASSOCIATED WITH STUBBORN HUDSON BAY HI PRES.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 446 AM EDT FRI MAY 17 2013

HEADING THRU THE WEEKEND INTO EARLY NEXT WEEK...PRESSURE GRADIENT
OVER THE UPPER LAKES WILL SLOWLY TIGHTEN BTWN LOW PRES SLOWLY MOVING
FROM THE WRN PLAINS TOWARD THE UPPER MISSISSIPPI VALLEY AND HIGH
PRES BUILDING IN THE VCNTY OF WRN HUDSON BAY. THIS WILL LEAD TO
EASTERLY WINDS GRADUALLY INCREASING INTO GENERALLY THE 15-25KT
RANGE. COULD BE SOME PERIODS OF HIGHER WINDS AT TIMES EARLY NEXT
WEEK...ESPECIALLY OVER WRN LAKE SUPERIOR WHERE FUNNELING/CHANNELING
WILL ENHANCE THE WINDS.
&&

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

$$

UPDATE...JLA
SHORT TERM...JLA
LONG TERM...07
AVIATION...KC
MARINE...07