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000
FXUS63 KMQT 050954
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
454 AM EST WED MAR 5 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 357 AM EST WED MAR 5 2014

SOME WEAK SHORTWAVE ENERGY OVER THE CWA EARLY THIS MORNING IS
HELPING TO DRIVE SOME LIGHT LES OVER NRN MARQUETTE COUNTY. THAT LES
SHOULD QUICKLY DIMINISH BY SUNRISE TODAY AS DRY AIR FILTERS INTO THE
AREA AND THE SHORTWAVE EXITS. A 1040MB SFC HIGH IS CURRENTLY
CENTERED JUST SW OF JAMES BAY...WITH A 500MB RIDGE ALONG THE
MANITOBA/ONTARIO BORDER. THE SFC HIGH WILL MOVE TO SRN QUEBEC BY 12Z
THU AS LOW PRESSURE MOVES INTO THE NRN PLAINS STATES. THE RESULTING
DRY AIR WITH THE SFC HIGH WILL KEEP THE FORECAST DRY TODAY AND
TONIGHT. SLY WINDS WILL INCREASE TONIGHT BETWEEN THE TWO SYSTEMS.

FOR TEMPS...GIVEN LOWS THIS MORNING OF 0F TO -20F...COLDEST INTERIOR
W AND INTERIOR E...AND MIXING TO AOB 900MB...HIGHS TODAY WILL
GENERALLY BE 10F-20F EVEN WITH 850MB TEMPS OF -10C /7-8C HIGHER THAN
YESTERDAY/. 850MB TEMPS INCREASE ANOTHER 3-5C TONIGHT WITH THE
INCREASING SLY FLOW AS CLOUDS MOVE INTO NWRN PARTS OF THE
CWA...WHICH WILL RESULT IN LOW TEMPS TONIGHT OF 5F TO -7F...COLDEST
INTERIOR CENTRAL AND E.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 453 AM EST WED MAR 5 2014

OVER THE NEXT 7 DAYS...VERY COLD AIR WILL CONTINUE TO LINGER ACROSS
MUCH OF CANADA...ESPECIALLY IN THE VCNTY OF HUDSON BAY. HOWEVER...
SINCE THE FLOW REGIME ACROSS THE CONUS WILL BE LOWER AMPLITUDE...
THIS VERY COLD AIR WILL STAY TO THE N OF UPPER MI THRU THIS FCST
PERIOD. THERE WILL REMAIN A TENDENCY FOR SOME DEGREE OF RIDGING OVER
WRN NAMERICA WHICH RESULTS IN A MEAN LOW AMPLITUDE TROF FROM THE
UPPER MISSISSIPPI VALLEY TO NEW ENGLAND. THIS WILL SET THE STAGE FOR
A TIGHT THERMAL GRADIENT ON MOST DAYS ROUGHLY ACROSS THE UPPER
MISSISSIPPI VALLEY/UPPER GREAT LAKES REGION. SHORTWAVES MOVING ALONG
IN THIS WNW FLOW PATTERN WILL THEN PROVIDE THE PROSPECT FOR PERIODIC
PCPN ACROSS THE UPPER LAKES. WHILE NO SIGNIFICANT PCPN APPEARS TO BE
IN THE OFFING...SHORTWAVES TRACKING ALONG THE TIGHT THERMAL GRADIENT
SUCH AS WILL BE OVER/NEAR THE AREA CAN SOMETIMES PRODUCE VERY NARROW
BANDS OF MDT OR EVEN HVY PCPN. WILL BE SOMETHING TO WATCH.
OTHERWISE...THE RETREAT OF ARCTIC AIR WILL RESULT IN TEMPS RETURNING
CLOSER TO NORMAL OVER THE NEXT 7 DAYS. HOWEVER...TEMPS COULD VARY
RATHER DRAMATICALLY FROM FCST IF THERMAL GRADIENT IS SHIFTED ONLY
SLIGHTLY FARTHER N OR S.

BEGINNING THU/FRI...SEVERAL SHORTWAVES WILL MOVE ACROSS THE UPPER
LAKES/NRN ONTARIO REGION...THE FIRST 2 ON THU AND THE LAST STRONGER
WAVE FRI. STRONG WAA/ISENTROPIC ASCENT REGIME DEVELOPS THU IN
ASSOCIATION WITH FIRST 2 WAVES. DESPITE THE STRONG ISENTROPIC
ASCENT...THERE ARE CONCERNS IN WHETHER DRIER AIR AT THE LOWER LEVELS
CAN BE OVERCOME. JUST N OF UPPER MI...SNOW IS MORE LIKELY TO OCCUR
AS ADDITIONAL FORCING PROVIDED BY A LEAD SHORTWAVE PASSING ACROSS
LAKE SUPERIOR/NRN ONTARIO EARLY IN THE DAY WILL HELP ERODE DRIER
AIR...ALLOWING REMAINING DRY AIR TO BE MORE EASILY OVERCOME BY
THE FOLLOWING WAVE. IN FACT...MODELS ARE IN NEARLY UNIFORM AGREEMENT
IN KEEPING SNOW MOSTLY N OF THE AREA THU. WILL THUS ONLY KEEP SCHC
POPS ACROSS THE KEWEENAW. OTHERWISE...IT WILL BE A BRISK DAY AS
SOUTHERLY WINDS BECOME GUSTY. NAM/GFS SHOW 35-45KT WINDS WITHIN 2KFT
AGL. FORTUNATETLY...STABLE LOW LEVELS WILL PREVENT SIGNIFICANT
MIXING. STILL...EXPECT GUSTS OVER 30MPH AT MANY LOCATIONS. CONTINUED
ISENTROPIC ASCENT...THOUGH WEAKER...COMBINED WITH APPROACH OF
STRONGER WAVE SHOULD EVENTUALLY RESULT IN SOME -SN LATER THU
NIGHT/FRI MORNING AS LOW-LEVELS FINALLY MOISTEN. ALTHOUGH MIXING
RATIOS ON THE 295K SFC (AROUND 700-750MB) ARE UP TO 3G/KG...
ISENTROPIC ASCENT BECOMES MUCH WEAKER THU NIGHT/FRI MORNING DUE TO
WINDS BECOMING ALIGNED NEARLY PARALLEL TO ISOBARS. COMBINED WITH
JUST MODEST DEEP LAYER FORCING...IT DOES NOT APPEAR THAT -SN WILL
RESULT IN MUCH ACCUMULATION...MAYBE AROUND AN INCH. WILL NEED TO
WATCH NOSE OF WARMER AIR PUSHING INTO THE AREA. COULD BE SOME
SLEET/-FZRA IF WARMING IS NOT SUFFICIENTLY COUNTERACTED BY
EVAPORATIVE COOLING. COLD FRONT SWEEPS THRU THE AREA FRI.
NORMALLY...WOULD HAVE TO DEAL WITH LES IN CAA REGIME...BUT SINCE
LAKE SUPERIOR IS MOSTLY ICE COVERED...POTENTIAL IS MINIMAL UNLESS
LARGER BREAKS IN THE ICE COVER OPEN IN THE BRISK WINDS THU (THAT
COULD VERY WELL HAPPEN). FOR NOW...ONLY EXPECT A FEW -SHSN/FLURRIES
IN INITIAL CYCLONIC FLOW BEHIND FRONT.

QUIET/DRY WEATHER RETURNS FOR FRI NIGHT/SAT AS HIGH PRES BUILDS INTO
THE NRN PLAINS/UPPER MISSISSIPPI VALLEY. HOWEVER...THE GFS/GEM SHOW
A SHORTWAVE DIVING SE THRU THE UPPER MISSISSIPPI VALLEY/UPPER GREAT
LAKES LATE SAT AFTN/EVENING. LAKE OF MOISTURE IS A PROBLEM...BUT
SINCE DEEP LAYER FORCING IS FAIRLY STRONG...THERE MAY BE SOME
FLURRIES AND PERHAPS A FEW -SHSN. DAYTIME HEATING WOULD HELP THAT
POTENTIAL...BUT AT THIS POINT...POTENTIAL IS SMALL ENOUGH TO LEAVE
MENTION OUT OF FCST...ESPECIALLY SINCE THE ECMWF/UKMET HAVE BEEN
CONSISTENTLY MUCH MUCH WEAKER WITH THIS WAVE.

SUN THRU TUE...LACK OF CONSISTENCY IN TIMING/STRENGTH OF SHORTWAVES
IN WNW FLOW PATTERN LEAD TO A LOW CONFIDENCE FCST WITH REGARD TO
PCPN. IT LOOKS LIKE THERE WILL BE AT LEAST 2 SHORTWAVES THAT WILL
TRACK THRU THE VCNTY OF THE UPPER LAKES. AS PREVIOUSLY MENTIONED...
THE TIGHT TEMP GRADIENT ACROSS THE REGION COULD RESULT IN NARROW
STREAKS OF HEAVIER PCPN WITH THE SHORTWAVES. HOWEVER...DUE TO
TIMING/TRACK ISSUES...LOW POPS...MOSTLY SCHC...WILL BE UTILIZED
UNTIL SOME CONSISTENCY EMERGES.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1233 AM EST WED MAR 5 2014

EXPECT VFR CONDITIONS AT ALL TAF SITES THROUGH THE FCST PERIOD. A
NEARLY COMPLETELY ICE COVERED LAKE SUPERIOR SHOULD MINIMIZE OR
ELIMINATE POTENTIAL FOR ANY STRATOCU OR LIGHT LES FORMATION UNDER
DEVELOPING NE FLOW.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 357 AM EST WED MAR 5 2014

EXPECT WINDS GENERALLY UNDER 20KT THROUGH TODAY AS HIGH PRESSURE
DOMINATES. SOUTHERLY WINDS WILL THEN BE ON THE INCREASE TONIGHT AND
THU AHEAD OF A LOW PRES TROUGH APPROACHING FROM THE W. OVER ERN LAKE
SUPERIOR...WINDS WILL INCREASE TO 20-30KT. THE TROUGH WILL CROSS THE
UPPER LAKES FRI...BRINGING A WIND SHIFT TO THE NW. WHILE THERE MAY
BE A PERIOD OF 15-25KT WINDS BEHIND TROUGH...WINDS WILL DIMINISH
INTO THE WEEKEND AS HIGH PRESSURE MOVES OVER THE REGION.
&&

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

$$

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