Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 210527
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
127 AM EDT THU MAY 21 2015

.UPDATE...
ISSUED AT 950 PM EDT WED MAY 20 2015

A SHROUD OF MID AND HIGH CLOUDS COVERS NORTHERN MI THIS EVENING.
SOME RAIN HAS BEEN FAR IN FAR SOUTHERN LOWER...BUT THE LOW LEVELS
ARE TOO DRY TO ALLOW PRECIP TO GET ANY FURTHER NORTH. NOTE THE 00Z
APX SOUNDING...WHICH WAS MOIST ABOVE 550MB BUT QUITE DRY BELOW.

CLOUD COVER UPSTREAM IS THINNING ACROSS NORTHERN WI...WESTERN
UPPER MI...AND LAKE SUPERIOR. ANTICIPATE SEEING PARTIAL CLEARING
FROM NW TO SE AFTER MIDNIGHT. THIS DOESN/T LEAVE A LOT OF TIME FOR
RADIATIONAL COOLING...GIVEN IT/S LIGHT BY 10Z THIS TIME OF YEAR.
BUT CURRENT READINGS ARE ALREADY IN THE 40S...SO WE DON/T HAVE FAR
TO FALL TO POSE A HAZARD TO TENDER VEGETATION.

GIVEN A RELATIVELY SOLID OVERCAST PRESENTLY...AND A SLOWER
CLEARING TREND...HAVE ADJUSTED MIN TEMPS VERY SLIGHTLY HIGHER.
THESE CHANGES ARE NOT LARGE ENOUGH TO JUSTIFY CHANGES TO THE
GOING FREEZE WARNING.

&&

.NEAR TERM...(THIS EVENING THROUGH TONIGHT)
ISSUED AT 326 PM EDT WED MAY 20 2015

...A SNEAKY FREEZE AGAIN...

SYNOPTIC PATTERN AND OBSERVATIONS:

THIS AFTERNOON...A SFC LOW IS POSITIONED NEAR THE ARKANSAS/LA BORDER
WITH AN INVERTED TROUGH EXTENDING NORTH THROUGH MO/IA....WHILE A
SHORTWAVE TROUGH WAS WORKING TOWARD THE MID MISSISSIPPI VALLEY.
STRONGER LOW TO MID LEVEL WAA WAS CENTERED IN IL...WHILE MORE
DYNAMICAL FORCING HIGHLIGHTED BY UPPER DIVERGENCE IN A DOUBLE JET
STRUCTURE...WAS DRIVING ACROSS NRN IL/SRN WISCONSIN. BOTH AREAS WERE
RESULTING IN FAIRLY WIDESPREAD RAIN SHOWERS. ACROSS NRN MI...WE WERE
SEEING A RAPID EXPANSION OF MID AND HIGHER LEVEL CLOUDS THROUGH NRN
LOWER AS EXPECTED...BUT EVEN FURTHER NORTH. UP TO THIS POINT...SFC
DEW POINTS HAVE TANKED AS PLANNED TOO...INTO THE 20S AND LOW 30S
ACROSS MOST ALL AREAS.

SYNOPTIC PATTERN EVOLUTION AND ASSOCIATED WEATHER:

WE ARE SITTING IN A RELATIVE AREA OF HIGHER PRESSURE AND FAIRLY
LIGHT WINDS THAT WILL FALL OFF TONIGHT...ESPECIALLY IN NRN LOWER
WHERE THE HIGH PRESSURE WILL BE LINGERING. ACROSS EASTERN UPPER...A
COLD FRONT WILL BE DROPPING SOUTH AND TIGHTENING THE PRESSURE
GRADIENT...WITH WINDS JUST ABOVE THE SFC INCREASING. THIS WILL HELP
TO KEEP THE BL A BIT MORE MIXED TONIGHT...WHERE LOWS WILL FALL TO
JUST BELOW FREEZING. ACROSS NRN LOWER...THE MID AND HIGH LEVEL
CLOUDS DRIVEN BY THE DYNAMICAL FORCING FROM THE SHORTWAVE DIVE ESE
FROM US THROUGH THE EVENING...WITH LITTLE IN THE WAY OF CLOUDS FOR
THE OVERNIGHT...DESPITE WAA ABOVE THE SFC. THIS IS A SNEAKY
SITUATION FOR LOW TEMPERATURES...BUT WITH SFC DEW POINTS TANKED THIS
AFTERNOON...CLEARING OVERNIGHT AND LIGHT/NEAR CALM WINDS...READINGS
IN THE UPPER 20S AND LOWER 30S WILL BE QUITE COMMON. COLDER READINGS
IN THE MIDDLE 20S FOR THE LOWEST LYING LOCALES. FRUIT CROP MANAGERS
AND PLANT/FLOWER GARDENERS NEED AS MUCH TIME TO PREPARE...WHICH
PROMPTED THE EARLIER ISSUANCE OF THE FREEZE WARNING. ADDITIONAL
FROST AND FREEZE PRODUCTS ARE LIKELY TO BE NEEDED FOR THURSDAY NIGHT
AND FRIDAY NIGHT (MORE ON THAT BELOW).

&&

.SHORT TERM...(THURSDAY THROUGH SATURDAY)
ISSUED AT 326 PM EDT WED MAY 20 2015

HIGH IMPACT WEATHER POTENTIAL: INCREASING FIRE WEATHER CONCERNS
THURSDAY AFTERNOON. MORE UNSEASONABLY CHILLY NIGHTS WITH ADDITIONAL
FROST AND FREEZE CONDITIONS EXPECTED THURSDAY NIGHT AND FRIDAY NIGHT.

PATTERN SYNOPSIS/ANTICIPATED EVOLUTION: NO SURPRISES WITHIN SHORT
AND MID RANGE GUIDANCE...A TESTAMENT TO JUST HOW SLOW AND AMPLIFIED
THE LONG WAVE PATTERN IS. PATTERN SIMPLY REMINISCENT OF ONE
EXPERIENCED MUCH OF THIS WINTER (REALLY...FOR THE LAST 2 1/2 YEARS!)
WITH RIDGING POKING UP INTO THE NORTHWEST TERRITORIES...ALL-THE-
WHILE ANOMALOUSLY DEEP TROUGHING RESIDES ACROSS NORTHEAST NOAM.
UNFORTUNATELY...NORTHERN MICHIGAN WILL REMAIN SQUARELY UNDER THE
INFLUENCE OF THE LATTER FEATURE...WITH ANOTHER REINFORCING SHOT OF
COLD AIR DIVING SOUTH ON ITS BACKSIDE BRINGING ADDITIONAL FROST AND
FREEZE CONCERNS THURSDAY NIGHT AND FRIDAY NIGHT.

PRIMARY FORECAST CONCERNS/CHALLENGES: ADDRESSING ALL FIRE WEATHER
PARAMETERS THURSDAY AFTERNOON AND OVERNIGHT TEMPERATURE TRENDS
THURSDAY AND FRIDAY NIGHT.

DETAILS: KINDA AN INTERESTING FORECAST HEADING THROUGH THURSDAY AS A
RELATIVELY MOISTURE STARVED COLD FRONT MAKES STEADY SOUTH PROGRESS
ACROSS THE AREA...EXITING OUR SOUTHERN ZONES TOWARD EVENING. DESPITE
MARGINAL MID LEVEL SUPPORT AND REALLY DRY LOW LEVELS (DEW POINTS
MIXING OUT THROUGH THE 30S INTO THE 20S)...NEARLY ALL GUIDANCE
CONTINUES TO PRODUCE SOME LIGHT SHOWERS. PERUSAL OF MODEL DERIVED
SOUNDINGS AND CROSS SECTIONS DO SHOW SOME HINTS OF MID LEVEL
MOISTURE...AND WHEN COMBINED WITH DIURNAL INSTABILITY TRENDS...MAY
BE JUST ENOUGH TO PRODUCE A FEW SPRINKLES/VERY LIGHT SHOWERS. BIGGER
STORY TIED TO ELEVATED FIRE WEATHER CONCERNS AS ALREADY RELATIVELY
DRY AIRMASS IS MADE MORE SO BY WHAT SHOULD BE EXCELLENT DEEP LAYER
MIXING. AS MENTIONED EARLIER...SEE LITTLE REASON AFTERNOON DEW
POINTS WON`T MIX OUT INTO AT LEAST THE UPPER 20S. COMBINE THIS WITH
DOWNSLOPE ENHANCED WARMING PRODUCING AFTERNOON HIGHS IN THE UPPER
60S DOWN NEAR SAGINAW BAY...AND MIN RH VALUES SHOULD DROP TO NEAR OR
BELOW CRITICAL LEVELS. SAID DEEP MIXING WILL PRODUCE GUSTY WEST
WINDS...WITH SPEEDS NEAR OR EXCEEDING 25 MPH. WHILE IT`S NOT LOOKING
LIKE WE WILL REACH CRITICAL LEVELS WITH TEMPERATURES...THE OTHER
PARAMETERS MENTIONED ABOVE DEFINITELY RAISES FIRE WEATHER
CONCERNS...ESPECIALLY IN THE HURON NATION FOREST AREA. WILL
INTRODUCE THIS CONCERN IN OUR LATEST HAZARDOUS WEATHER PRODUCTS.

NEXT SURGE OF COLD AIR FOLLOWS THIS FRONTAL PASSAGE...AND WITH
CLEARING SKIES...SETS THE STAGE FOR ANOTHER CHILLY NIGHT. SOME
PRESSURE GRADIENT REMAINS DURING THE EVENING...BUT 1000MB
GEOSTROPHIC WINDS FALLING BELOW 10 KNOTS STRONGLY SUPPORTS NEAR OR
FULL DECOUPLING HEADING INTO THE EARLY MORNING HOURS. WARMER START
TO THE EVENING MAY TEMPER JUST HOW COLD TEMPERATURES REACH...BUT
STILL FEEL WIDESPREAD 20S ARE DOABLE ACROSS INTERIOR REGIONS...WITH
LOWER/MIDDLE 30S ELSEWHERE.

REST OF THE FORECAST DOMINATED BY HIGH PRESSURE AND PLENTY OF
SUNSHINE. STILL WELL BELOW NORMAL TEMPERATURES FRIDAY...AND WITH THE
COOLER START AND HIGH PRESSURE SETTLING DIRECTLY OVERHEAD DURING THE
EVENING...STARTING TO HAVE A FEELING FRIDAY NIGHT MIGHT BE AN
AWFULLY COLD ONE. GUIDANCE HAS STEADILY TRENDED COLDER...WITH
READINGS VERY SIMILAR TO THOSE THURSDAY NIGHT. GOING TO DO THE
SAME...WHICH UNFORTUNATELY RESULTS IN ANOTHER WIDESPREAD FROST AND
FREEZE EVENT. AIRMASS REALLY BEGINS TO MODIFY QUICKLY SATURDAY
MORNING...RESULTING IN ONE FANTASTIC START TO THE HOLIDAY WEEKEND AS
HIGHS REACH WELL UP INTO THE 60S.

&&

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 326 PM EDT WED MAY 20 2015

FOR THE START OF THE EXTENDED PERIOD THE HIGH PRESSURE WILL BE MOVED
OFF AND SOUTHERLY WINDS WILL RESULT. TEMPERATURES ARE EXPECTED TO
INCREASE TO NEAR NORMAL OR SLIGHTLY ABOVE NORMAL...UPPER 60S...WITH
THIS WIND CHANGE. THE INCREASE OF TEMPERATURE SHOULD CONTINUE
THROUGH TO THE END OF THE EXTENDED FORECAST PERIOD. THE
UNCERTAINTY CONTINUES FOR THE TIMING OF THE CHANCE OF
PRECIPITATION AS THE 500MB TROUGH REMAINS OVER THE PACIFIC. THE
MODELS ARE STRUGGLING TO AGREE ON THE ARRIVAL OF THE SYSTEM...WITH
ONE SHOWING INCREASED PRECIPITATION POSSIBILITIES FOR SUNDAY MORNING
AND THE OTHER SHOWING NO PRECIPITATION UNTIL MONDAY MORNING. THE
INCREASED CHANCE FOR PRECIPITATION DOES APPEAR TO LAST UNTIL THE
MIDDLE OF NEXT WEEK. WILL KEEP SLIGHT CHANCE FOR THUNDER FOR SUNDAY
AND MONDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 125 AM EDT THU MAY 21 2015

NO AVIATION ISSUES IN THE NEAR TERM WITH VFR CONDITIONS EXPECTED
THROUGH THURSDAY MORNING.

&&

.MARINE...
ISSUED AT 326 PM EDT WED MAY 20 2015

NO MARINE HEADLINES ANTICIPATED. WESTERLY WINDS HAVE BEEN FUNNELING
THROUGH THE STRAITS AND HAVE RESULTED IN NEAR ADVISORY LEVEL
SPEEDS...BUT RELATIVE HIGHER SFC PRESSURES ACROSS THE REGION HAVE
KEPT WIND/WAVE ISSUES AT BAY. THIS WILL NOT BE THE CASE TOMORROW AS
A COLD FRONT CROSSES AND WINDS SHIFT OUT OF THE NW AND INCREASE.
ADVISORY LEVEL GUSTS ARE ANTICIPATED FOR AT LEAST A HANDFUL OF
NEARSHORE WATERS INTO THURSDAY EVENING. HIGH PRESSURE THEN GRADUALLY
BUILDS INTO THE REGION FOR FRIDAY AND SATURDAY.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR MIZ016>036-041-
     042.

LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

UPDATE...JAZ
NEAR TERM...SMD
SHORT TERM...MSB
LONG TERM...TKT
MARINE...SMD



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