Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 310346
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1146 PM EDT WED JUL 30 2014

.SYNOPSIS.../ISSUED AT 340 PM/

A SERIES OF UPPER LEVEL DISTURBANCES WILL MOVE ACROSS THE REGION
BRINGING DAILY CHANCES FOR SHOWERS THROUGH SATURDAY...ESPECIALLY
DURING THE AFTERNOON HOURS. TEMPERATURES WILL SLOWLY INCREASE EACH
DAY INTO THE UPCOMING WEEKEND.

&&

.SHORT TERM.../ISSUED AT 340 PM/...THIS EVENING AND TONIGHT

THE DOMINANT WEATHER FEATURE FOR THE REGION REMAINS THE LONGWAVE
UPPER LEVEL TROUGH AND CLOSED MID LEVEL LOW PRESSURE SYSTEM THAT IS
CENTERED OVER JAMES BAY. LOWER MICHIGAN IS SITUATED WITHIN THE BROAD
CYCLONIC FLOW AT THE PERIPHERY...A LOCATION THAT HAS BEEN AT THE
MERCY OF EPISODIC SHORTWAVES AND VARYING LOW TO MID LEVEL SATURATION
PINWHEELING AROUND THE LOW.

TWO SEPARATE MIDLEVEL TROUGH AXES ARE PROVIDING SOME FOCUS AND
GENERAL ORGANIZATION TO THE PRECIPITATION IN THE GREAT LAKES REGION
THIS AFTERNOON. THE FIRST TROUGH AXIS IS QUICKLY CENTERING INTO
PORTIONS OF LAKE ERIE AND OHIO. RADAR AND LIGHTNING OBSERVATIONS
SHOW THE VAST MAJORITY OF THE THUNDERSTORM ACTIVITY IS OCCURRING
AHEAD OF THIS AXIS...WITHIN A RIBBON OF MUCH DEEPER MOISTURE. THE
SECOND OF THE TWO TROUGH AXES WILL SOON ENTER THE NORTHERN REACHES
OF FAR NORTHWESTERN LAKE SUPERIOR. SATELLITE ALONG WITH VARIOUS
OBSERVATIONAL DATASETS HAVE CONSISTENTLY SHOWN A STRONG SHORTWAVE
TIED TO THIS -DIV ZONE ALONG WITH A GOOD SURGE OF ATLANTIC
WRAPAROUND MOISTURE. SHOWER AND ISOLATED THUNDERSTORMS HAVE
BLOSSOMED WITHIN THE OVERLAP OF THESE INGREDIENTS OVER PORTIONS OF
ONTARIO AND LAKE SUPERIOR.

FOR TONIGHT...NWP ADVERTISES A CONTRACTION OF THE CLOSED LOW DUE
TO AN IMPRESSIVE LATE JULY INNER JET CORE DIGGING STRAIGHT
SOUTHWARD. THIS UPPER LEVEL JET AXIS NOW OVER LAKE SUPERIOR WILL
SWING RAPIDLY TO WESTERN PA/NY BY 12Z THURSDAY. THIS STRONG
ACCELERATION COMPONENT WILL MAKE IT DIFFICULT TO KEEP ORGANIZED
FORCING IN ANY ONE LOCATION FOR ANY LENGTH OF TIME...THUS THE
PRESERVATION OF MODEST PRECIP MENTION.

.LONG TERM.../ISSUED AT 340 PM/...THURSDAY THROUGH NEXT WEDNESDAY

MID LEVEL HEIGHTS WILL BE ON THE RISE ACROSS LOWER MI BY THURSDAY
MORNING AS SHORT WAVE ENERGY DEPARTS TOWARD UPSTATE NEW YORK AND
DRAGS THE CORE OF EXTREMELY COLD AIR ALOFT /500MB TEMPS DOWN TO
-20C/ EAST OF THE REGION. THE ANOMALOUSLY DEEP UPPER LOW WILL
HOWEVER REMAIN JUST SOUTH OF JAMES BAY THROUGH THE DAY THURSDAY AND
WILL DRIVE A SURFACE TROUGH INTO THE NORTHERN GREAT LAKES. SW FLOW
IN ADVANCE OF THIS TROUGH WILL LEAD TO SOME MOISTURE ADVECTION
THROUGH THE DAY...PROVING AN OPPORTUNITY FOR WEAK DAYTIME
DESTABILIZATION. THE HIGHEST INSTABILITY SHOULD BE OVER THE SAGINAW
VALLEY AND THUMB REGION GIVEN THE CLOSER PROXIMITY TO THE MOISTURE
PLUME. FARTHER SOUTH...LOWER SFC DEWPOINTS AND BUILDING MID LEVEL
HEIGHTS WILL BE A LARGE LIMITING FACTOR FOR AFTERNOON
CONVECTION...SUPPORTING JUST A SLIGHT CHANCE OF LATE DAY
SHOWERS/THUNDERSTORMS. A PLUME OF STEEPER MID LEVEL LAPSE RATES IS
FORECAST TO EXPAND INTO LOWER MI THURS NIGHT UNDER MID LEVEL W-SW
FLOW...WHILE SUBTLE MOISTURE ADVECTION PERSISTS IN THE LOW LEVELS.
THIS SUGGESTS A SLIGHT CHANCE OF SOME CONVECTION DURING THE
NIGHT...WITH SLIGHTLY HIGHER CHANCES CLOSER TO THE REMNANT LOW LEVEL
CONVERGENCE AXIS EXPECTED TO BE RESIDING OVER CENTRAL LOWER MI.

THE UPPER LOW WILL BE DRIVEN INTO EASTERN CANADA FRIDAY INTO
SATURDAY. THERE IS GOOD AGREEMENT AMONG THE MODEL SUITE THAT SHORT
WAVE ENERGY ROTATING AROUND THE BACK SIDE OF THIS TROUGH WILL
UNDERGO SOME AMPLIFICATION AS IT TRACKS FROM THE UPPER MS VALLEY
THURS INTO THE GREAT LAKES AND OHIO VALLEY FRI INTO SATURDAY. SUBTLE
COOLING ALOFT AND FAIRLY GOOD LOW LEVEL MOISTURE QUALITY WILL LEAD
TO MODEST DAYTIME DESTABILIZATION BOTH FRI AND SAT....SUPPORTIVE OF
THE CURRENT CHANCE OF SHOWERS/THUNDERSTORMS. MOST LIKELY TIMING BOTH
DAYS WILL BE LATE AFTERNOON AND EVENING. LOW LEVEL WARM AIR
ADVECTION ON THURS WILL BOOST TEMPS BACK CLOSER TOWARD TYPICAL MID
SUMMER TEMPERATURES. LITTLE OVERALL CHANGE IN THE THERMAL PROFILE
AND EXPECTED MIXING HEIGHTS WILL SUSTAIN THESE NEAR NORMAL TEMPS
INTO THE WEEKEND.

WEATHER PATTERN SHOWS LITTLE CHANGE WITH A GENERAL RIDGE WEST/TROUGH
EAST SET UP...PRECLUDING ANY BIG WARM-UPS. UPPER TROUGH AXIS/COLD
POOL WILL CONTINUE...SO DIURNALLY ENHANCED SHOWERS AND THUNDERSTORMS
WILL BE A POSSIBILITY THROUGH MUCH OF NEXT WEEK. TEMPERATURES ARE
EXPECTED TO REMAIN NEAR TO SLIGHTLY BELOW NORMAL.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1140 PM EDT WED JUL 30 2014

VFR CONDITIONS THROUGHOUT THE TAF PERIOD. UPPER LEVEL TROUGH IS
PRODUCING SPORADIC RAIN SHOWERS ACROSS NORTHERN LOWER
MICHIGAN. RAIN SHOWERS SHOULD END BY THE MORNING HOURS WITH
TROUGH AXIS EXPECTED TO PASS THROUGH THE FORECAST AREA. ANOTHER
MID LEVEL DISTURBANCE IS EXPECTED TO IMPACT NORTHERN MICHIGAN
DURING THE AFTERNOON HOURS...GENERATING SHOWERS ONCE AGAIN.
ALTHOUGH CONFIDENCE LEVEL IS LOW...AT THIS TIME RAIN CHANCES LOOK
THE BEST FOR THE APN AREA.

&&

.MARINE.../ISSUED AT 340 PM/

WINDS WILL REMAIN FAIRLY LIGHT THROUGH THE END OF THE WEEK...WITH
THE MOST NOTABLE PERIOD OF WINDS OCCURRING FROM THE SOUTHWEST
THURSDAY AND THURSDAY NIGHT AS A WEAK TROUGH MOVES ACROSS THE
WESTERN AND CENTRAL GREAT LAKES. OTHERWISE...EXPECT THE AREA TO
REMAIN UNDER A COOL PATTERN WITH SHOWERS AND THUNDERSTORMS
DEVELOPING EACH DAY...MOSTLY DURING THE AFTERNOON AND EVENING.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.

&&

$$

AVIATION...TL





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