Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 280725
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
325 AM EDT THU AUG 28 2014

.SYNOPSIS...
ISSUED AT 323 AM EDT THU AUG 28 2014

HIGH PRESSURE SETTLING OVER THE GREAT LAKES WILL GENERATE SEASONAL
CONDITIONS ACROSS NORTHERN MICHIGAN TODAY AND TONIGHT. LOW PRESSURE
FROM THE CENTRAL PLAINS WILL START MOVING INTO TO THE REGION FRIDAY
THROUGH SATURDAY NIGHT...BRINGING PERIODS OF RAIN AND POTENTIAL
THUNDERSTORMS WITH SIGNIFICANT AMOUNTS OF RAIN POSSIBLE.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 159 AM EDT THU AUG 28 2014

...SUNNY SKIES THEN THICKENING CLOUDS TONIGHT AND RAIN ON THE WAY...

IMPACTS: NONE.

CURRENT WEATHER AND SYNOPTIC PATTERN:

A SFC COLD FRONT WILL WELL OFF TO OUR SOUTH AND EAST EARLY THIS
MORNING...WITH QUITE THE DRY AIR MASS OVERHEAD AND INCREASED
SUBSIDENCE UNDER INCREASING HEIGHTS/RIDGE ALOFT. THE LOW LEVEL COLD
POOL WAS STILL COLD ENOUGH TO GENERATE SOME NARROW CORRIDORS OF LAKE
STRATUS TUCKED UP UNDER AN INVERSION BASED NEAR H8.
OTHERWISE...SKIES WERE PRETTY DARN CLEAR...AND RADIATIONAL COOLING
WAS QUITE STRONG. TEMPERATURES HAVE BEEN ABLE TO FALL OFF INTO THE
40S FOR MOST AREAS...IN LIGHT WINDS/LAND BREEZE SCENARIO. THE LOWEST
LYING AREAS WERE AS COOL AS THE UPPER 30S...WHERE PATCHY FROST MAY
BE POSSIBLE. CLOSEST WEATHER OF NOTE UPSTREAM IS A CIRCULATING AREA
OF LOW PRESSURE DRIFTING INTO NE/KS. AREAS OF SHOWERS AND STORMS
ARCED AROUND THIS LOW PRESSURE.

SYNOPTIC PATTERN/WEATHER EVOLUTION:

ANY REMNANT LAKE INDUCED/AIDED STRATUS WILL QUICKLY BURN OFF AFTER
SUNRISE...AS DIURNAL PROCESSES TAKE OVER WITH TERRESTRIAL HEATING.
NOT MUCH CHANGE IN THE LOW LEVEL THERMAL FIELDS WITH LITTLE IN THE
WAY OF ADVECTIONS IN A LIGHT WIND SCENARIO. SO THE DAY SHOULD BE
PRETTY CLOSE TO YESTERDAY...WITH HIGHS IN THE UPPER 60S AND LOWER
70S. SOME SCATTERED CUMULUS WILL GET LIFTED UNDERNEATH THE
AFOREMENTIONED INVERSION...CLUSTERED WITHIN LAKE BREEZE CONVERGENCE
REGIONS...WHICH WILL ULTIMATELY WIND UP IN THE VERY CENTRAL INTERIOR
SECTIONS OF EASTERN UPPER AND NRN LOWER.

THERE WILL BE SOME INCREASED HIGH LEVEL CLOUDS HEADING INTO LATE IN
THE AFTERNOON...AS INITIAL VORTICITY MAXIMA EJECT OUT OF THE
UPSTREAM LOW PRESSURE AND WARM FRONT...AND INTO THE WESTERN GREAT
LAKES. BELIEVE THIS INITIAL ENERGY WILL NOT BE ABLE TO DO ANY MORE
THAN MOISTEN THE HIGH LEVELS OF THE ATMOSPHERE...DUE TO THE
ANTECEDENT DRYNESS. THIS ENERGY LOOKS TO EXIT EAST OVERNIGHT...WHILE
THE DATA IS A BIT NEBULOUS ON WHEN THE NEXT BOUT OF VORTICITY ROLLS
ON IN. AM NOT AS CONFIDENT IN NEXT WAVE ARRIVING OVERNIGHT...ALONG
WITH SOME RAIN. HOWEVER...IT WILL BE AT LEAST GETTING CLOSE TO US.
WILL PUSH BACK THE LIKELY RAINS TO AREAS NEAR AND WEST OF GTV BAY.
ANY RAIN WILL BE LIGHT...AS IT TAKES FOREVER TO SATURATE THE LOWER
LEVELS OF THE ATMOSPHERE. NOT MUCH QPF DUE TO THIS...AND DUE TO
OVERALL WEAKISH FORCING...AND WARM FRONT STILL WELL UPSTREAM.

LOWS LIKELY FALLING OFF QUICKLY INTO THE LOW TO MID 50S...AND
STABILIZING OVERNIGHT WITH THE INCREASED BLANKET OF CLOUDS.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 323 AM EDT THU AUG 28 2014

HIGH IMPACT WEATHER POTENTIAL: HEAVY RAIN FROM THE FRIDAY/SATURDAY
STORM.

PRIMARY FORECAST CHALLENGES: RAINFALL ENHANCED BY ELEVATED
CONVECTION...FRIDAY INTO SATURDAY.

OVERVIEW...MODELS ARE IN AGREEMENT WITH THE EVOLUTION OF THE
UPCOMING WEEKEND STORM AS THE SHALLOW 500 MB CUTOFF LOW IN THE
CENTRAL ROCKIES GETS ABSORBED INTO THE ALMOST ZONAL FLOW CURRENTLY
OVER THE CANADIAN/U.S. BORDER. ONCE THE WEEKEND IS DONE, THERE IS A
BRIEF REPRIEVE, THEN A MORE AMPLIFIED TROUGH MOVES ACROSS THE US AND
INTO THE UPPER GREAT LAKES. SO THE FORECAST WILL LOOK LIKE THIS...

(8/29)FRIDAY...MODELS CONTINUE TO BE IN GOOD AGREEMENT THROUGH THE
DAY WITH THE GOOD DYNAMIC LIFT ALONG THE WARM FRONT. THE WARM FRONT
STARTING TO ENTER N MICHIGAN AROUND 12Z AND PUSHING TO AT LEAST THE
STRAITS BY 00Z. AT THE SAME TIME, A 500 MB JET STREAK OF ABOUT 40
KNOTS MOVES THROUGH E UPPER BY 18Z. THIS WILL PUT GOOD UPWARD MOTION
IN NW LOWER BETWEEN 12Z AND 20Z AS THE RRQ OF THE JET COINCIDES WITH
THE WARM ADVECTION. IT IS ALSO DURING THIS TIME WITH THE WARM
ADVECTION AND THE JET DYNAMICS THAT THUNDER BECOMES POSSIBLE, SO
WILL CONTINUE THE GRADUAL MOVEMENT OF ELEVATED CONVECTION WITH THE
WARM SECTOR APPROACHING.


FRIDAY NIGHT...BY 00Z WITH THE WARM ADVECTION SLOWS AS THE SFC LOW
MOVES INTO C UPPER RELAXING THE SFC PRESSURE GRADIENT, THUS LOWERING
THE UPWARD MOTION DUE TO THE WARM ADVECTION. HOWEVER, THE 500 MB JET
STREAK CONTINUES TO REMAIN OVER THE REGION WITH 35-40 KNOTS. THIS
GENERATES A SECOND SFC LOW OVER WISCONSIN WHICH IN TURN GENERATES
MORE WARM ADVECTION. THE MODELS SHOW DIFFERENT AREAS THAT COULD BE
TARGETED BY MESOSCALE FEATURES(GFS IN C AND E UPPER WHILE ECMWF IN
THE STRAITS). HOWEVER, IT IS PROBABLE THAT SOMEONE IS GOING TO GET A
PERIOD OF HEAVY RAIN, ESPECIALLY AS THE ELEVATED CONVECTION GETS
INTO THE ACT.

(8/30)SATURDAY...THE CONTINUED STALLED FRONT OVER THE FORECAST AREA,
AND THE 500 MB JET CONTINUE TO CAUSE ISSUES UNTIL THE AFTERNOON,
THEN IT LOOKS LIKE A 500 MB SHORTWAVE TROUGH MOVES INTO THE UPPER
GREAT LAKES. THIS WILL CONTINUE TO HELP CONVECTION THROUGH THE DAY,
BUT ALSO KICK THIS SYSTEM OUT OF THE FORECAST AREA BY THE LATE
AFTERNOON. OVERNIGHT, THE THUNDERSTORMS BEGIN TO MOVES OUT AS THE
MOISTURE IN THE 700-500 MB LAYER BEGINS TO DRY OUT WITH THE LAYER RH
FALLING FROM 90% TO LESS THAN 40% BY 12Z. THE 850 MB RH FALLS AS
WELL, WITH THE RH ENDING UP LESS THAN 60% BY 12Z.

EXTENDED (SUNDAY THROUGH WEDNESDAY)...(8/31)SUNDAY...WE GET ON THE
BACK SIDE OF THE LOW, BUT THE MODELS HAVE SPED THE DRYING UP A BIT
AS ALLUDED TO IN THE PREVIOUS PERIOD. SO THE FORECAST IS FOR DRYING
OUT. (9/1)LABOR DAY...A SFC LOW SPINS UP AND MOVES IN ONTARIO WITH
THE GFS PUTTING IT NEAR JAMES BAY AND ECMWF IN LAKE SUPERIOR. THIS
WILL KICK OFF THUNDERSTORMS THAT WILL MOVE ACROSS THE FORECAST AREA.
BY THE NIGHT, IT WILL BE DRY. (9/2)TUESDAY...THE MODELS ARE STILL UP
IN THE AIR WITH THIS TIME. THERE IS A 500 MB TROUGH IN THE REGION,
BUT WITH LIMITED MOISTURE. THE MODELS SHOW HIT AND MISS RAIN SHOWERS
WILL LEAVE THE DRY FORECAST WAS INHERITED. IF THIS PATTERN WERE TO
HOLD, THEN PROBABLY ISOLATED SHOWERS AT BEST. (9/3)WEDNESDAY...IT
LOOKS LIKE IT SHOULD REMAIN DRY AS HIGH PRESSURE PASSES SOUTH OF THE
FORECAST AREA, AND 500 MB FLOW BECOMES ZONAL AGAIN.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 159 AM EDT THU AUG 28 2014

...SOME LAKE GENERATED VFR STRATUS THEN SUNNY...

BANDS OF VFR STRATUS WILL AFFECT AREAS MAINLY BETWEEN TVC/PLN UNTIL
SHORTLY AFTER DAYBREAK. THEN...SKIES WILL RAPIDLY TURN SUNNY WITH
ONLY SOME FEW-SCT CUMULUS FIRING OFF IN CONVERGENCE AREAS FROM
DEVELOPING LAKE BREEZES THIS AFTERNOON. THIS CUMULUS WILL FADE WITH
NIGHTFALL...WHILE SKIES WILL BE INCREASING IN HIGH LEVEL CLOUDS.
THESE CLOUDS WILL THICKEN OVERNIGHT...WITH SOME LIGHT RAIN
POSSIBILITIES BY DAYBREAK OVER TVC/MBL...POSSIBLY PLN. NO
RESTRICTIONS TO VSBYS EXPECTED THROUGH THIS TAF PERIOD.

WINDS WILL BE QUITE LIGHT TODAY...TURNING ONSHORE THIS AFTERNOON AND
THEN LIGHT AGAIN TONIGHT BUT A PUSH TO MORE OUT OF A SOUTHERLY
DIRECTION.


&&

.MARINE...
ISSUED AT 159 AM EDT THU AUG 28 2014

WEAK WINDS WITH SFC HIGH PRESSURE SETTLING IN OVERHEAD. THIS HIGH
PRESSURE EXITS EAST TONIGHT...AHEAD OF WEAK LOW PRESSURE AND A WARM
FRONT LIFTING TOWARD THE WESTERN GREAT LAKES. SOUTHERLY WINDS DO
INCREASE...WHILE OVERLAKE INSTABILITY ALSO WEAKENS. STILL FORESEE
SOME GUSTS TO 20 KNOTS DEVELOPING TONIGHT AND INTO FRIDAY.
CONDITIONS TURN INCREASINGLY STABLE OVER THE LAKES FRIDAY-FRIDAY
NIGHT WHILE LOW LEVEL WINDS RAMP UP MORE SIGNIFICANTLY. THERE IS A
CHANCE THAT SOME SMALL CRAFT ADVISORY WINDS DEVELOP FOR A PERIOD OF
TIME ALL NEARSHORES...ESPECIALLY LAKE MICHIGAN AND WHITEFISH BAY. A
FRONTAL BOUNDARY AND WEAKER PRESSURE GRADIENT EXPECTED TO MOVE IN
SATURDAY AND INTO SATURDAY NIGHT.

RAINS ARE LIKELY FRIDAY-FRIDAY NIGHT IN EASTERN UPPER...WITH AN EVEN
BETTER CHANCE AT RAIN SET FOR SATURDAY IN ALL OF THE
NEARSHORES.


&&

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

&&

$$

SYNOPSIS...SMD
SHORT TERM...SMD
LONG TERM...JL
AVIATION...SMD
MARINE...SMD





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