Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 120729
AFDMQT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MARQUETTE MI
329 AM EDT SAT JUL 12 2014

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 429 PM EDT FRI JUL 11 2014

WV IMAGERY AND RUC ANALYSIS INDICATED A ZONAL PATTERN THROUGH THE
NRN CONUS BETWEEN A TROUGH OVER CNTRL CANADA AND A RIDGE OVER THE
SRN PLAINS. A WEAK SHORTWAVE TROUGH OVER LAKE SUPERIOR INTO CNTRL
UPPER MI HELPED PRODUCE SOME LIGHT SHOWERS ACROSS THE CWA TODAY.
SCT/ISOLD SHRA/TSRA FROM NEAR KINL INTO N CNTRL MN HAD DEVELOPED
ALONG A COLD FRONT/TROUGH AHEAD OF ANOTHER WEAK SHRTWV MOVING
THROUGH NORTH DAKOTA. MOSTLY CLOUDY SKIES OVER UPPER MI HAD LIMITED
TEMPS TO THE LOWER TO MID 70S AND LIMITED MLCAPE VALUES TO LESS THAN
400 J/KG.

TONIGHT...EXPECT THAT SHRA/TSRA OVER NRN MN WILL EXPAND IN COVERAGE
AND MOVE TOWARD UPPER MI. HOWEVER...WITH ONLY MARGINAL INSTABILITY
FCST OVER THE AREA...MUCAPE INTO THE 400-800 J/KG RANGE...THE
CONVECTION SHOULD WEAKEN WITH ONLY ISOLD TSRA. SCT SHRA COVERAGE
WITH CHANCE POPS WAS MENTIONED GIVEN THE WEAK FORCING ASSOCIATED
WITH THE FRONT AND SHRTWV SLIDING THROUGH THE NRN GREAT LAKES. THE
REMAINING SHOWERS ARE EXPECTED TO MOVE INTO THE ERN CWA LATE THIS
EVENING AND DIMINISH FROM WEST TO EAST OVERNIGHT.

SATURDAY...THE WEAKENING COLD FRONT THROUGH UPPER MI WILL PROVIDE A
BOUNDARY/FOCUS FOR POTENTIAL SHRA/TSRA DEVELOPMENT...ESPECIALLY WITH
ONSET OF STRONGER DAYTIME HEATING. EXPECT THE GREATEST PCPN COVERAGE
OVER THE SOUTH AND THROUGH ERN UPPER MI WHERE THE HIGHER RES MODELS
SUGGEST THE LOW LEVEL CONV WILL BE STRONGEST. MLCAPE VALUES TO NEAR
1K J/KG...PER GEM-REGIONAL AND GFS COMBINED WITH 0-6KM SHEAR VALUES
OF 35-40 KNOTS COULD SUPPORT SOME STRONG AND POSSIBLY SEVERE STORMS
IF CLOUD DEPENDENT INSTABILITY IS REALIZED. THE MODELS HAVE ALSO SHOWN A
CONSISTENT SIGNAL THAT SHRA/TSRA WILL MOVE INTO WI ASSOCIATED WITH
STRONGER SHORTWAVE TROUGH. THERE IS STILL TIMING/POSITION UNCERTAINTY
ON HOW IT WOULD AFFECT MAINLY SRN UPPER MI BY LATE AFTERNOON.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 328 AM EDT SAT JUL 12 2014

NAM SHOWS A CLOSED 500 MB LOW OVER SOUTH CENTRAL CANADA 12Z SUN WITH
A 500 MB TROUGH DIGGING INTO THE GREAT LAKES REGION. UPPER AIR
PATTERN AMPLIFIES OVER THE AREA 12Z MON WITH THE LOW MOVING OVER THE
AREA ON MON. AS THE LOW MOVES OVER THE AREA ON MON...EXPECT SOME
INSTABILITY SHOWERS TO BREAK OUT WITH THE HIGHEST POPS DURING THE
PEAK DIURNAL HEATING. NAM SHOWS SOME DEEPER MOISTURE AND 850-500 MB
Q-VECTOR CONVERGENCE MOVING THROUGH THE AREA ON MON INTO MON NIGHT.

WILL HAVE SOME SMALL CHANCE POPS IN FOR THE ERN CWA SUN MORNING AND
THEN GO DRY FOR SUN AFTERNOON AND SUNDAY EVENING. WITH APPROACH OF
THE UPPER LEVEL LOW ON MON...WILL HAVE POPS INCREASING TO LIKELY IN
A FEW PLACES MON WITH PEAK DIURNAL HEATING HAVING THE HIGHEST POPS
IN THE AFTERNOON. WITH LOSS OF DIURNAL HEATING MON NIGHT...HAVE POPS
DECREASING BACK TO CHANCE TO SLIGHT CHANCES. OVERALL...DID NOT MAKE
TOO MANY CHANGES TO THE GOING FORECAST. TEMPERATURES WILL BEGIN THE
COOLING TREND THIS FORECAST PERIOD AND LOWERED HIGHS A BIT FOR SUN
THROUGH MON NIGHT.

IN THE EXTENDED...GFS AND ECMWF SHOW A DEEP 500 MB TROUGH AND CLOSED
LOW OVER THE ERN HALF OF NORTH AMERICA WITH VERY COLD TEMPERATURES
OVER THE AREA 12Z TUE. THE TROUGH REMAINS NEARLY STATIONARY INTO THU
BEFORE PATTERN MODIFICATION TAKES PLACE WITH THE TROUGH AND
AMPLIFICATION BREAKING DOWN. A RIDGE MOVES INTO THE ROCKIES 12Z FRI.
WHAT THIS WILL MEAN IS THE COOL CONDITIONS WILL CONTINUE FOR MOST OF
THE FORECAST PERIOD WITH A SLOW MODERATION IN TEMPERATURES. SFC
HIGH PRESSURE REMAINS IN CONTROL OF THE WEATHER AND LOOKS COOL AND
DRY FOR THE MOST PART. WILL KEEP SOME SMALL POPS IN FOR TUE WITH
DEPARTING UPPER LOW IN THE AREA.
&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 140 AM EDT SAT JUL 12 2014

VFR CONDITIONS...WITH MAINLY HIGHER MVFR CONDITIONS AT KCMX...PREVAIL
OVERNIGHT. AS WINDS SHIFT AROUND TO A W TO NW DIRECTION BEHIND COLD
FROPA THIS MORNING...THE UPSLOPE WINDS AT KIWD/KCMX MAY RESULT IN A
PERIOD OF IFR CONDITIONS AND POTENTIALLY LIFR. MVFR CONDITIONS MAY
DEVELOP AT KSAW. ALL TERMINALS SHOULD RETURN TO VFR LATE MORNING INTO
THE AFTN. THERE MAY BE SHRA/TSRA AROUND KSAW THIS AFTN...BUT
LOCATION/COVERAGE OF ANY SHRA/TSRA DEVELOPMENT IS TOO UNCERTAIN AT
THIS POINT TO INCLUDE A MENTION IN FCST.
&&

.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 429 PM EDT FRI JUL 11 2014

SOUTH WINDS OF UP TO 20 KTS...POSSIBLY 25 KTS AT HIGHER PLATFORMS
ABOVE MARINE LAYER...EXPECTED INTO THIS EVENING WILL DIMINISH
OVERNIGHT WITH WINDS SHIFTING TO SW. AS SCT SHOWERS ASSOCIATED WITH A
WEAK COLD FRONT OR TROUGH MOVE THROUGH LAKE SUPERIOR...FOG WILL BE
POSSIBLE ACROSS THE ENTIRE LAKE WITH THE TROUGH PASSAGE. LIGHT WINDS
WILL CONTINUE THROUGH SUNDAY BEFORE ANOTHER TROUGH PASSES
SOUTHEASTWARD ACROSS LAKE SUPERIOR SUNDAY NIGHT. GUSTY NORTHWEST
WINDS TO 20 KNOTS EXPECTED BEHIND THIS TROUGH EARLY NEXT WEEK AS HIGH
PRESSURE BUILDS OVER THE NORTHERN PLAINS.
&&

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

$$

SHORT TERM...JLB
LONG TERM...07
AVIATION...ROLFSON
MARINE...JLB





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