Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 191948
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
348 PM EDT FRI SEP 19 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 518 AM EDT FRI SEP 19 2014

WV IMAGERY AND RUC ANALYSIS INDICATED A LOW AMPLITUDE PATTERN WITH A
MID/UPPER LEVEL RIDGE FROM THE PLAINS TOWARD THE UPPER MS VALLEY AND
A TROUGH FROM SRN SASK INTO THE NRN ROCKIES. AT THE SFC...SRLY FLOW
WAS INCREASING OVER THE UPPER MS VALLEY INTO THE WRN LAKES AS THE
PRES GRADIENT STRENGTHENS BETWEEN A TROUGH FROM MANITOBA INTO THE
NRN PLAINS AND HIGH PRES OVER QUEBEC. INCREASED LOW LEVEL MOISTURE
ADVECTION HAS ALSO BROUGHT SOME LOW CLOUDS INTO MUCH OF CNTRL WI AND
UPPER MI. SOME LIGHT SHOWERS OVER NR CNTRL MN WERE SUPPORTED BY
310K-315K ISENTROPIC ASCENT WITH FAVORABLE 850 MB THETA-E ADVECTION
ON 40-50 KNOT WINDS.

TODAY...RAIN SHOULD CONTINUE TO SPREAD TOWARD UPPER MI AS A WEAK
SHORTWAVE AND THE STRONGER 850 MB THETA-E ADVECTION MOVE IN. WITH
MODEL TRENDS HAVE SLOWING THE ARRIVAL OF THE PCPN INTO UPPER MI AND
THE PRESENCE OF A DRY 850-600 MB LAYER...RAIN CHANCES WILL INCREASE
INTO THE WEST HALF OF THE CWA MAINLY IN THE MID TO LATE AFTERNOON.
ONLY CHANCE FOR TSRA WAS MENTIONED OVER THE FAR WEST WHERE MUCAPE
VALUES CLIMB TO NEAR 800 J/KG. AS THE LOW CLOUDS MIX OUT TOWARD
AFTERNOON AND DAYTIME HEATING INCREASES...A BETTER PORTION OF THE
40-50 KNOT 900-850 MB WINDS MAY MIX TOWARD THE SFC. HOWEVER...THE
DEPTH OF THE MIXED LAYER SHOULD MAINLY ALLOW WIND GUSTS TO NEAR 30
KNOTS. HOWEVER...THERE MAY BE A PERIOD LATE THIS AFTERNOON OVER THE
EAST WHERE THE STRONG WINDS ABOVE THE LAKE MI MARINE LAYER ARE ABLE
TO MIX TOWARD THE SFC OVER THE EAST AND WINDS GUST INTO THE 30-40 MPH
RANGE FOR A TIME...ESPECIALLY FROM NEAR GRAND MARAIS TO NEWBERRY.

TONIGHT...SCT/NMRS SHOWERS AND A FEW THUNDERSTORMS WILL SPREAD
THROUGH THE CWA IN THE EVENING AS THE SFC AND MID LEVEL TROUGH APPROACH
AND THE AXIS OF HIGHER MOISTURE(PWAT TO 1.5 INCHES)/INSTABILITY
(MUCPAE TO NEAR 1K J/KG) MOVE IN. THE POTENTIAL FOR ELEVATED TSRA
REMAINS WITH 850 MB DEWPOINTS TO NEAR 14C.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 348 PM EDT FRI SEP 19 2014

SATURDAY NIGHT AND SUNDAY...A SERIES OF MID-LEVEL SHORTWAVES WILL BE
TRACKING AROUND THE BASE OF A BROADER TROUGH ACROSS ONTARIO AND
HUDSON BAY. A SUBTLE SHORTWAVE AND SFC COLD FRONT WILL BE EXITING
THE EASTERN CWA AT THE BEGINNING OF THE PERIOD WHILE A STRONGER
SHORTWAVE TRACKS SE ACROSS MN. MEANWHILE...AN ASSOCIATED SFC LOW
WILL BE FORMING ON A TRAILING SFC TROUGH FROM THE COLD FRONT
CROSSING THE CWA SATURDAY AFTERNOON. WEAK LOW-LEVEL ISENTROPIC LIFT
AND A NEGATIVE UPPER PV ANOMALY WILL TRACK ACROSS NORTHERN WI AND
MUCH OF UPPER MI SATURDAY NIGHT...THOUGH DEEP MOISTURE WILL HAVE
DECREASED BY THIS TIME BEHIND THE LEAD SHORTWAVE/COLD FRONT.
HOWEVER...OVERALL DYNAMICS WILL BE ENOUGH TO RESULT IN RAIN ACROSS
MUCH OF THE CWA..ESPECIALLY THE SOUTHWEST HALF. THE MID-LEVEL TROUGH
AXIS DOES NOT CLEAR THE CWA UNTIL LATE IN THE DAY SUNDAY...SO
ISOLATED TO SCATTERED SHOWERS COMBINED WITH PLENTY OF CLOUDS SHOULD
CONTINUE UNTIL AT LEAST SUNDAY AFTERNOON.

SUNDAY NIGHT THROUGH MONDAY NIGHT...MID-LEVEL NW FLOW WILL SET-IN
OVER THE REGION THROUGH THIS PERIOD. A SFC RIDGE EXTENDING
NORTHEASTWARD FROM HIGH PRESSURE OVER THE CENTRAL PLAINS WILL CROSS
THE CWA SUNDAY NIGHT. TEMPS ARE A BIT TRICKY TO PIN DOWN AS THERE
ARE INDICATIONS THAT LOW-LEVEL CLOUDS MAY LINGER INTO THE EVENING
ACROSS THE AREA. HOWEVER...CLEARING SHOULD OCCUR OVERNIGHT. WENT
WITH THE LOWER END OF TEMP GUIDANCE IN THE MID 30S FOR INTERIOR
LOCATIONS.

A WEAK SHORTWAVE WILL TRACK SOUTHEASTWARD OUT OF FAR NORTHERN
CANADA...PASSING BETWEEN LAKE SUPERIOR AND JAMES BAY MONDAY
AFTERNOON AND EVENING. AN ASSOCIATED SFC TROUGH WILL THEN CROSS
UPPER MI MONDAY NIGHT. MID-LEVEL MOISTURE IS LACKING...AND WITH THE
RIGHT ENTRANCE OF THE UPPER JET OVERHEAD AND MID-LEVEL Q-VECTOR CONV
TIED DIRECTLY TO THE TROUGH...AM EXPECTING A DRY FRONTAL PASSAGE
WITH ONLY SOME SCATTERED CLOUDS.

TUESDAY THROUGH FRIDAY...A GRADUAL WARMING TREND WILL COMMENCE AS
ANOTHER SFC HIGH PRESSURE TRACKS SOUTHEASTWARD ACROSS NORTHERN
ONTARIO TUESDAY WHILE A MID-LEVEL RIDGE BUILDS OVER THE UPPER MS
VALLEY. THIS WILL BRING DRY WEATHER THROUGH MUCH OF WEDNESDAY. AS
THE RIDGE AXIS MOVES OVER THE UPPER GREAT LAKES WEDNESDAY NIGHT INTO
THURSDAY...A SHORTWAVE TROUGH MOVING ALONG THE INTERNATIONAL BORDER
WILL CROSS NORTH OF UPPER MI THURSDAY. THERE IS SOME MODEL
DISAGREEMENT ON THE STRENGTH OF THE TROUGH...AND THUS HOW EFFECTIVE
IT WILL BE IN PICKING UP A SLOW-MOVING CLOSED-LOW OVER THE CENTRAL
PLAINS. THE ECMWF IS A BIT STRONGER WITH THE NORTHERN TROUGH AND
THUS PICKS UP MOST OF THE ENERGY FROM THE CLOSED-LOW. THE GFS IS
WEAKER WITH THE NORTHERN TROUGH AND STRUGGLES TO KICK OUT THE
CLOSED-LOW. BOTH SOLUTIONS BRING CHANCES OF PRECIP TO THE CWA...BUT
THE ECMWF SHOWS MUCH MORE COVERAGE. GIVEN HOW ANY SUBTLE DIFFERENCES
IN THE NORTHERN TROUGH COULD MEAN THE DIFFERENCE BETWEEN PICKING UP
THE LOW OR LEAVING IT BEHIND...HAVE OPTED TO CONTINUE CONSENSUS
CHANCE POPS FOR WEDNESDAY NIGHT INTO THURSDAY.
&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 128 PM EDT FRI SEP 19 2014

TIGHT PRESSURE GRADIENT AHEAD OF APPROACHING SURFACE TROUGH WILL
BRING GUSTY SOUTH WINDS TO ALL TERMINALS THROUGH THIS EVENING. FLOW
IS ESPECIALLY FAVORABLE FOR KSAW...AND EXPECT CONTINUED GUSTS TO
30KT OR PERHAPS HIGHER THERE INTO THE EARLY EVENING HOURS. OVERALL
COVERAGE AHEAD OF THE TROUGH HAS NOT BEEN EXTENSIVE...THEREFORE HAVE
KEPT VCSH IN FORECAST FOR IWD LATE THIS AFTERNOON WITH THE BETTER
CHANCE OF SHRA PUSHING IN DURING THE EVENING HOURS. AN ISOLATED
THUNDERSTORMS CANNOT BE RULED OUT WITH ELEVATED INSTABILITY OVER THE
AREA. OVERNIGHT TONIGHT...CONTINUED MOISTENING WILL OCCUR ALLOWING
EACH TAF SITE TO FALL TO IFR OR POSSIBLY EVEN LIFR CONDITIONS. WINDS
OVERNIGHT WILL DECREASE AS THE PRESSURE GRADIENT SHIFTS FARTHER EAST
AND MIXING DECREASES.
&&

.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 518 AM EDT FRI SEP 19 2014

SOUTHERLY WINDS WILL INCREASE TODAY WITH LOW PRESSURE APPROACHING
FROM THE WEST AND HIGH PRESSURE JUST EAST OF LAKE SUPERIOR SHIFTING
EASTWARD. 20-30KT SOUTHERLY WINDS ARE EXPECTED ACROSS THE CENTRAL
AND EAST TODAY. A FEW GALES TO 35 KNOTS WILL BE POSSIBLE FOR THE
HIGHER PLATFORMS AND CLOSER TO THE UPPER MI SHORELINE. THE 20-30KT
SOUTH WINDS WILL GRADUALLY DIMINISH ACROSS THE EAST HALF OF THE LAKE
FRIDAY NIGHT THROUGH SATURDAY AS THE TROUGH MOVES ACROSS LAKE
SUPERIOR. EXPECT A PERIOD OF WESTERLY WINDS OF UP TO 20 KNOTS
SATURDAY AFTERNOON AND NW WINDS TO 20 KNOTS SUNDAY BEHIND THIS
TROUGH. WINDS WILL REMAIN UNDER 20 KNOTS THROUGH MUCH OF NEXT WEEK AS
A SERIES OF HIGH PRESSURE SYSTEMS MOVES OVER THE UPPER GREAT LAKES.
THE ONE EXCEPTION WILL BE THE CHANCE OF NORTH WINDS UP TO 25 KNOTS
MONDAY AFTERNOON AND EVENING BEHIND A QUICK-MOVING LOW PRESSURE
TROUGH.
&&

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

$$

SHORT TERM...JLB
LONG TERM...KLUBER
AVIATION...KEC
MARINE...JLB





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