Area Forecast Discussion
Issued by NWS Marquette, MI

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000
FXUS63 KMQT 290842
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
442 AM EDT FRI AUG 29 2014

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 359 PM EDT THU AUG 28 2014

DRY WEATHER WILL COME TO AN END LATE TONIGHT INTO FRIDAY AS A
MOISTURE-LADEN SYSTEM BRINGS MODERATE RAINFALL TO UPPER MICHIGAN.

TONIGHT...A MID-LEVEL RIDGE CURRENTLY ALIGNED SOUTH TO NORTH OVER
UPPER MI WILL SHIFT EASTWARD THROUGH THE NIGHT. MEANWHILE...A TROUGH
OVER ALBERTA THIS AFTERNOON WILL TRACK EAST AND BEGIN TO PICK UP A
SLOW-MOVING TROUGH OVER THE CENTRAL PLAINS. A SFC LOW OVER SE SD AND
AN ASSOCIATED WARM FRONT STRETCHING FROM WESTERN IA TO CENTRAL IL
WILL LIFT NORTHWARD THROUGH THE NIGHT. THIS WARM FRONT HAS BEEN
PRODUCING MODERATE RAINFALL ACROSS NORTHERN IA AND SOUTHERN MN
TODAY. MUCH OF THIS RAIN IS BEING FORCED BY ASCENT ON THE 300 TO
310K THETA SFCS. AMPLE MOISTURE WITH PWAT VALUES SURPASSING 1.5
INCHES AND INCREASING LOW-LEVEL FLOW WILL SUPPORT CONTINUED
WIDESPREAD PRECIP ALONG THE FRONT.

THE FIRST QUESTION WITH THIS SYSTEM IS THAT OF TIMING. A FAIRLY DRY
ANTECEDENT AIR MASS ABOVE 850 HPA AS NOTED BY THE 12Z GRB RAOB
SUPPORTS SOME INITIAL SUPPRESSION OF PRECIP. THIS BEHAVIOR HAS BEEN
APPARENT ON RADAR IMAGERY SW OF THE AREA. THEREFORE...HAVE
MAINTAINED A DRY FORECAST THROUGH THIS EVENING FOR ALL
LOCATIONS...WITH RAIN REACHING THE WI BORDER AFTER 04Z. WHILE THERE
IS PLENTY OF DRY AIR...THE AFOREMENTIONED MOISTURE ALONG WITH ADDED
SUPPORT UNDER THE RIGHT ENTRANCE OF A WEAK UPPER JET SHOULD PRODUCE
HIGHER-INTENSITY RAINFALL THAT WILL QUICKLY ERODE THE DRY LAYER.
ADDITIONALLY...MUCH OF THE INITIAL FORCING FROM ISENTROPIC
ASCENT/FGEN WILL OCCUR IN ABOVE-FREEZING AIR. THE WARM RAIN
PROCESSES IN THIS LAYER WOULD BE EFFICIENT AT PRODUCING MODERATE TO
SOMETIMES HEAVY RAINFALL INTO FRIDAY MORNING.

THE NEXT QUESTION REVOLVES AROUND LOCATION. FORCING ALONG THE WARM
FRONT WILL BE ENOUGH TO PRODUCE WIDESPREAD COVERAGE OF SHOWERS LATE
TONIGHT INTO FRIDAY MORNING. SOME OF THE 12Z GUIDANCE HAS MOVED THE
GREATEST PRECIP CHANCES FARTHER WEST. HAVE HAVE OPTED TO MAINTAIN
THE HIGHEST CHANCES ACROSS THE SW AS THE THOSE MODEL RUNS WERE
HAVING DIFFICULTY HANDLING ONGOING PRECIP. OVERALL...THE CENTRAL CWA
IS EXPECTED TO SEE 0.5 TO 1.0 INCH OF RAINFALL BY LATE FRIDAY
MORNING...WITH LOCALIZED GREATER THAN 1 INCH AMOUNTS POSSIBLE.

FRIDAY...AS THE WARM FRONT LIFTS ACROSS THE CWA IN THE
MORNING...EXPECT A DECREASE IN PRECIP COVERAGE ACROSS THE WEST AND
CENTRAL CWA. WITH ABUNDANT LOW-LEVEL MOISTURE AND A PERSISTENT JET
INFLUENCE AHEAD OF A TROUGH MOVING OUT OF THE NORTHERN
PLAINS...SCATTERED SHOWERS WILL REMAIN POSSIBLE FROM LATE MORNING
INTO THE AFTERNOON. AS THE TROUGH TO THE WEST NEARS THE CWA BY LATE
AFTERNOON...SHOWER COVERAGE WILL INCREASE ACROSS THE WESTERN CWA.

WITH LITTLE TO NO INSTABILITY...EVEN ELEVATED...AHEAD OF THE WARM
FRONT...HAVE OPTED TO REMOVE ALL THUNDER FROM THE FORECAST THROUGH
FRIDAY MORNING. HOWEVER...POST-FRONTAL TEMPS SHOULD BE WARM ENOUGH
TO ALLOW FOR SOME SFC BASED INSTABILITY ACROSS THE WEST AND CENTRAL
CWA. CAPE VALUES OVER 500 J/KG WILL BE POSSIBLE...BUT RESIDUAL CLOUD
COVER SHOULD PREVENT ANYTHING MORE.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 439 AM EDT FRI AUG 29 2014

A RATHER UNSETTLED LABOR DAY WEEKEND LOOKS TO BE IN STORE FOR UPPER
MICHIGAN...ALTHOUGH SUNDAY LOOKS LIKE IT WILL REMAIN DRY. THE SHORT
WAVE TROUGH MOVING THROUGH THE WESTERLY FLOW ALOFT WILL PASS ACROSS
UPPER MICHIGAN ON SATURDAY. RAIN/RAIN SHOWERS WILL LIKELY BE ONGOING
ACROSS MUCH OF THE FORECAST AREA SATURDAY MORNING WITH DEEP MOISTURE
OVER THE REGION AND MODERATE MID LEVEL Q-VECTOR CONVERGENCE UNDER
THE RIGHT ENTRANCE REGION OF THE UPPER JET. BEST RAIN WILL LIKELY BE
ACROSS THE CENTRAL AND EAST THROUGH EARLY AFTERNOON WHERE THE
DEFORMATION AXIS WILL BE LOCATED. WITH PRECIPITABLE WATER VALUES
STILL AROUND 175 PERCENT OF NORMAL SATURDAY...THERE IS STILL AN
OPPORTUNITY FOR MODERATE RAINFALL ESPECIALLY WITH THE WARM CLOUD
DEPTH STILL AROUND 11 KFT. ONLY NEGATIVE TO HEAVY RAINFALL WOULD BE
THE LACK OF SIGNIFICANT INSTABILITY WHICH WOULD KEEP DEEPER
CONVECTION FROM BEING A CONCERN. AS SUCH...WILL RAISE POPS TO
CATEGORICAL ACROSS THE ENTIRE FORECAST AREA ON SATURDAY...WITH
DIMINISHING POPS DURING THE AFTERNOON.

WITH CONTINUED TROUGHINESS ACROSS THE EAST IN THE EVENING...WILL
HOLD ONTO CHANCE POPS UNTIL THE TROUGH AXIS PASSES EAST. MAIN
CONCERN SATURDAY NIGHT WILL BE THE FOG DEVELOPMENT. WITH THE
WIDESPREAD RAINFALL ON SATURDAY COMBINED WITH WEAK HIGH PRESSURE
BUILDING ACROSS THE UPPER GREAT LAKES...IT WOULD SEEM LIKE A
FAVORABLE ENVIRONMENT FOR DENSE FOG DEVELOPMENT SAT NIGHT INTO
SUNDAY MORNING. OTHERWISE...SUNDAY SHOULD BE A FAIRLY QUIET DAY WITH
WEAK HEIGHT RISES ACROSS THE AREA AHEAD OF THE DEEPER TROUGH OVER
THE PLAINS. THIS SHOULD ALLOW TEMPS TO RISE TO CLOSE TO NORMAL AS
MOST OF THE LOWER CLOUD SHOULD HAVE DISSIPATED IN THE MORNING HOURS.

THE PLAINS UPPER TROUGH MOVES EASTWARD SUNDAY NIGHT INTO MONDAY.
MODELS ARE IN QUITE GOOD AGREEMENT IN SHOWING THE TROUGH AND
ASSOCIATED COLD FRONT TO PASS THROUGH THE AREA MONDAY MORNING. THE
MORNING TIMING SHOULD PRECLUDE ANY SIGNIFICANT CHANCE FOR SEVERE
WEATHER DESPITE THE STRONG WIND FIELDS AND 50 KT LLJ. AT LEAST RIGHT
NOW...IF THERE WERE TO BE ANY SEVERE WEATHER WITH THIS SYSTEM ACROSS
UPPER MICHIGAN...IT WOULD OCCUR IN THE LATE MORNING INTO THE
AFTERNOON ACROSS THE CENTRAL AND THE EASTERN U.P. RIGHT ALONG THE
FRONT AND WHEN THE LEFT EXIT REGION OF THE JET IS OVERHEAD. WILL
MAINTAIN LIKELY POPS STARTING ACROSS THE WEST SUN NIGHT AND THEN
ACROSS THE ENTIRE FORECAST AREA ON MONDAY.

FOR THE REMAINDER OF THE EXTENDED...ZONAL FLOW DEVELOPS ACROSS THE
NORTHERN TIER AS A BROAD RIDGE EXTENDS ACROSS THE SOUTH. THE WEATHER
WILL STAY GENERALLY QUIET AND SEASONABLE TUE AND WED WITH WEAK SFC
HIGH PRES IN CONTROL. BETTER CHANCES FOR SHOWERS AND STORMS BY
THURSDAY WITH A FRONTAL BOUNDARY MOVING INTO THE AREA IN W-NW FLOW.
AT THIS TIME...IT LOOKS LIKE THU COULD END UP BEING FAIRLY WARM
AHEAD OF THIS FRONT IF THE ECMWF VERIFIES. BEYOND THURSDAY...IT
LOOKS LIKE ANOTHER COOL DOWN FOR NEXT WEEKEND WITH CANADIAN HIGH
PRESSURE JUST TO OUR NORTH.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 127 AM EDT FRI AUG 29 2014

VFR CONDITIONS ARE EXPECTED INTO LATE TONIGHT. LOW PRESSURE
APPROACHING FROM THE SW WILL BRING RAIN AND QUICKLY LOWER CIGS LATE
TONIGHT FOR ALL SITES. IFR CIGS ARE EXPECTED FOR SAW AND CMX...WITH
NEAR IFR CONDITIONS FOR IWD...BY 15Z FRIDAY. GIVEN UPSLOPE ASSISTANCE
WITH SSE FLOW...CIGS AT SAW AND CMX MAY FALL BELOW ALTERNATE LANDING
MINS. ALTHOUGH CONFIDENCE IS LOW...SOME IMPROVEMENT TO MVFR LATE FRI
AFTERNOON AT SAW IS POSSIBLE. OTHERWISE...AN EXTENDED PERIOD OF SUB-
IFR CIGS IS THEN EXPECTED TO CONTINUE INTO SATURDAY.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 359 PM EDT THU AUG 28 2014

HIGH PRESSURE OVER LAKE HURON WILL SHIFT EAST OVERNIGHT AS A WARM
FRONT ASSOCIATED WITH A LOW OVER EASTERN SD MOVES NORTHWARD ACROSS
WI. INCLUDING THIS WARM FRONT...SEVERAL WEAK TROUGHS WILL MOVE
NORTHEAST ACROSS THE UPPER GREAT LAKES REGION THROUGH SATURDAY. THE
WEAK PRESSURE GRADIENT ASSOCIATED WITH THESE FEATURES WILL KEEP
WINDS BELOW 20KTS THROUGH THE WEEKEND. RAINFALL EXPECTED LATE
TONIGHT THROUGH SATURDAY WILL BRING THE POTENTIAL FOR FOG TO DEVELOP
OVER LAKE SUPERIOR...ESPECIALLY OVER THE NORTHEAST...AND CONTINUE
INTO SUNDAY MORNING. A STRONGER TROUGH LIFTING NORTHEAST ACROSS THE
AREA ON MONDAY WILL LIKELY LEAD TO SOUTHERLY WINDS TO 25KTS SUNDAY
NIGHT INTO MONDAY.
&&

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

$$

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






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