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000
FXUS63 KAPX 211816
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
216 PM EDT TUE MAY 21 2013

.SYNOPSIS...
ISSUED AT 346 AM EDT TUE MAY 21 2013

A STORM SYSTEM IN THE PLAINS WILL TAKE ITS TIME MOVING INTO THE
GREAT LAKES THIS WEEK. THE STORM SYSTEM WILL EVENTUALLY EXIT EAST OF
THE REGION THURSDAY. THIS PATTERN WILL SET THE STAGE FOR CONTINUED
MILD TEMPERATURES...ALONG WITH SEVERAL CHANCE OF SHOWERS AND
THUNDERSTORMS THROUGH MIDWEEK.

HIGH PRESSURE WILL BUILD INTO THE GREAT LAKES FRIDAY AND SATURDAY.
THIS PATTERN WILL GENERATE PLENTY OF SUN AND SEASONAL
TEMPERATURES...OVER NORTHERN MICHIGAN THROUGH THE UPCOMING HOLIDAY
WEEKEND.

&&

.UPDATE...
ISSUED AT 215 PM EDT TUE MAY 21 2013

LOW CLOUDS QUICKLY MIXING OUT ACROSS A GOOD PART OF NRN LOWER
MICHIGAN...AS ANTICIPATED. SFC TEMPS RESPONDING NICELY WITH
READINGS JUMPING QUICKLY TO THE LOWER TO MIDDLE 70S. HAVE NUDGED
FORECAST MAX TEMPS UP A FEW DEGREES AS A FEW SPOTS LIKELY TO REACH
80F.

CONVECTION...SPC MESO ANALYSIS PAGE REVEALING A POCKET OF AROUND 250
J/KG LOWEST 100 MB MLCAPE ACROSS A GOOD PART OF NRN LOWER MICHIGAN
WITH LITTLE CINH. SHOWERS/THUNDER STILL LOOKING POSSIBLE ACROSS
PARTS OF NRN LOWER MICHIGAN OVER THE NEXT FEW HOURS PROVIDED WE
HAVE ENOUGH LOW LEVEL FOCUS...WHICH APPEARS MOST LIKELY TO BE
M-32 NORTHWARD IN THE VCNTY OF THE LINGERING SFC FRONT...AND TO A
LESSER EXTENT ACROSS THE HIGHER TERRAIN. ONE NOTE...SPC DAY ONE
OUTLOOK HAS PULLED THE NRN PART OF NORTHERN LOWER MICHIGAN OUT OF
THE SLIGHT RISK...NO DOUBT DUE TO THE LIMITED INSTABILITY. WILL
SEE HOW IT GOES.

UPDATE ISSUED AT 1059 AM EDT TUE MAY 21 2013

ROUND OF OVERNIGHT CONVECTION NOW EXITING THE NORTHEAST PART OF
THE CWA WITH RAIN FREE CONDITIONS ACROSS MOST OF NRN LOWER
MICHIGAN AT THIS JUNCTURE. SOME CLEARING TAKING SHAPE ACROSS NRN
LOWER MICHIGAN ALTHOUGH LOW STRATUS DECK HAS RE-DEVELOPED ACROSS
NW LOWER MICHIGAN...PERHAPS THE RESULT OF COOL/MOIST MARINE AIR
GETTING LOFTED OVER A WARM MOIST BOUNDARY LAYER ON S/SW LOW LEVEL
FLOW.

REST OF TODAY...EXPANDING STRATUS INTO NRN LOWER MICHIGAN WILL OF
COURSE IMPEDE SFC HEATING. BUT EVENTUALLY EXPECT LOWER CLOUDS TO
MIX OUT TO A GOOD DEGREE AS WE GET INTO THE AFTERNOON HOURS. SO
QUESTION IS...DO WE SEE ADDITION CONVECTION THIS AFTERNOON.

MODIFIED FORECAST SOUNDINGS USING UPPER 70S SFC TEMPS AND
DEWPOINTS AROUND 60 (ALLOWING FOR SOME MIXING) YIELD 500 TO 1000
J/KG MLCAPE THIS AFTERNOON...LESS THAN MONDAY...BUT WITH LITTLE
CONVECTIVE INHIBITION. HOWEVER...NOT QUITE THE TRIGGER/LOW LEVEL
FORCING THAT WE HAD YESTERDAY. BUT...SFC FRONT REMAINS DRAPED
ACROSS NRN LOWER MICHIGAN THIS MORNING BASICALLY BISECTING THE
M-32 CORRIDOR...AND WILL REMAIN MORE OR LESS STATIONARY THROUGH
THE DAY. LOW LEVEL CONVERGENCE IN THE VCNTY OF THE FRONT AS WELL
AS OROGRAPHIC LIFT MAY PROVE ENOUGH TO GET CONVECTION GOING THIS
AFTERNOON...LIKELY AFTER 2 PM. WILL FOCUS HIGHEST POPS OVER THE
TIP OF THE MITT AREA AND DOWN THROUGH NE LOWER MICHIGAN WHERE LOW
LEVEL CONVERGENCE WILL BE MAXIMIZED.

SEVERE WEATHER? POSSIBLE...GIVEN 40 TO 50 KNOT MID LEVEL SW FLOW
AND RESULTING 30 TO 40 KNOT 0-6KM BULK SHEAR LEADING TO POTENTIAL
STORM ORGANIZATION. INSTABILITY IS ON THE WEAKER SIDE...BUT COULD
BE MADE UP FOR WITH SOME STORM ORGANIZATION. ALL TOLD...CANNOT
RULE OUT THE POTENTIAL FOR A FEW CELLS TO PRODUCE SEVERE CRITERIA
WIND AND/OR HAIL THROUGH EARLY EVENING.

UPDATE ISSUED AT 634 AM EDT TUE MAY 21 2013

FIRST SWATH OF SHOWERS AND STORMS LIFTING UP TOWARD EASTERN
UPPER...WITH THE STORMS MORE SO LOCKED IN OVER NE LOWER...TRACKING
TOWARD DRUMMOND ISLAND. NEXT BATCH OF RAIN...WITH LESSER CHANCES
FOR EMBEDDED THUNDER...LIFTING INTO THE GTV BAY AND SAGINAW BAY
REGIONS. THERE IS NO LOW CLOUD SEEN...AND ALTHOUGH A BRIEF LOW
CLOUD DECK IS POSSIBLE FOR A BRIEF TIME THIS MORNING...DO BELIEVE
THAT REAL GOOD WARMING WILL OCCUR THROUGH THE DAY ACROSS M-68
SOUTH. THIS WILL ALLOW US TO REVEAL 1500 OR SO J/KG FOR ADDITIONAL
STORM DEVELOPMENT. NOT SEEING A REAL GOOD TRIGGER STILL...WITH THE
EXCEPTION FOR WEAK CONVERGENCE AROUND THE FRONT WHICH WILL TRY AND
EASE ITS WAY NORTH OF M-68. ALSO...MAYBE OROGRAPHIC LIFT CAN BE A
CATALYST FOR ADDITIONAL STORMS. WILL KEEP THE AFTERNOON AND EVENING
FORECAST THE SAME FOR NOW...AS THERE IS NO INDICATION STILL FOR A
CAP...DESPITE THE RISING HEIGHTS LATER TODAY AND THE EXPECTATION
FOR SUBSIDENCE BEHIND DEPARTING MID LEVEL TROUGH/PRECIPITATION.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 346 AM EDT TUE MAY 21 2013

SOMEWHAT OF A MESSY PATTERN OUT THERE RIGHT NOW...WITH CLOSED
UPPER LEVEL LOW PRESSURE ACROSS SOUTH DAKOTA WITH A SHORTWAVE
TROUGH LIFTING NE THROUGH THE MID MISSISSIPPI VALLEY. A
RE-ENERGIZED H8 LLJ OF 35-45KT WAS USHERING IN THE NEXT BATCH OF
DEEPER MOISTURE (PWATS APPROACHING 1.65") UP OUR WAY...AND
PROVIDING THE LOW LEVEL FORCING WHILE THE UPPER LEVELS WERE BEING
AIDED BY UPPER DIVERGENCE ASSOCIATED WITH RIGHT ENTRANCE REGION OF
MID/UPPER LEVEL JET. SOME ISOLATED ACTIVITY WAS DEVELOPING ALONG
M-55...BUT THE MAIN BATCH OF SHOWERS WAS STILL WORKING UP THROUGH
SRN LAKE MICHIGAN. STRONGEST OF STORMS WERE WELL SOUTH OF US
ACROSS NW INDIANA/SW LOWER...WHERE LATEST DATA SUGGESTS THAT THE
LLJ WAS BEING DIRECTED MORE WEST-EAST. WHILE MUCH OF THE MOISTURE
ADVECTION MAY PUSH THE BETTER RAINFALL OFF TO OUR SOUTH...LATEST
VAD WIND PROFILES ARE STILL SHOWING A STRENGTHENING SOUTH WINDS
ACROSS WISCONSIN.

THROUGH THE MORNING...THE UPPER LEVEL JET/DIVERGENCE WILL LIFT
ACROSS THE WESTERN GREAT LAKES ALONG WITH THE AFOREMENTIONED MID
LEVEL TROUGH. DEEP LAYER LIFT AND MOISTURE ADVECTION WILL RESULT
IN A PERIOD OF SHOWERS AND EMBEDDED THUNDERSTORMS. MUCAPE OF
SEVERAL HUNDRED J/KG IS STILL LOOKING TO NOT BE ENOUGH FOR 35-45KT
OF EFFECTIVE BULK SHEAR TO PRODUCE ANY WIDESPREAD SEVERE
WEATHER...BUT ISOLATED SEVERE STORMS WITH HAIL ARE NOT OUT OF THE
QUESTION. WILL SWING THIS INITIAL ROUND OF PRECIPITATION NORTHWARD
THROUGH THE MORNING. AREAS OF FOG...LOCALLY DENSE OFF LAKE
HURON...WILL CONTINUE TO PLAGUE MUCH OF NE LOWER AND THE STRAITS
REGION. THIS IS ALONG AND NORTH OF A NEAR STATIONARY FRONTAL
BOUNDARY WHERE EASTERLY FLOW IS COMING OFF LAKE HURON. I DO
BELIEVE THIS WILL BE A PROBLEM THROUGH A GOOD CHUNK OF THE
DAY...WITH LOW CLOUDS AND SOME FOG TO GRADUALLY DEVELOP INTO
MORE OF EASTERN UPPER. THIS TO OCCUR AS THE LOW LEVEL FLOW TRIES
TO TURN MORE SOUTHERLY BEHIND DEPARTING TROUGH AND ARRIVING WEAK
SFC LOW TRACKING TOWARD THE STRAITS.

THIS AFTERNOON...OF COURSE...THE BIG QUESTION WILL BE HOW MUCH
CLEARING OUT WILL WE GET THIS AFTERNOON?..AND WHAT WILL THE
IMPLICATIONS BE ON TEMPERATURES AND DEVELOPING DIURNAL
INSTABILITY?...ESPECIALLY OF INTEREST CONSIDERING THE DATA SHOWING
AN UNCAPPED ATMOSPHERE WITH WET BULBS DROPPING TO ROUGHLY 9KFT.
CLOUDS ARE LIKELY TO LINGER INTO THE AFTERNOON BEHIND DEPARTING
PRECIPITATION...AIDED BY OVERALL SUBSIDENCE AND HEIGHT RISES
EXPECTED IN THE MID LEVELS. A DEEPER SSW FLOW IS EXPECTED TO
DEVELOP ACROSS NRN LOWER...BUT THE WARM FRONT IS LIKELY TO NOT GET
THROUGH THE STRAITS/LAKE HURON COAST. THIS DEEPER SOUTHERLY
FLOW...IN THEORY...OUGHT TO EAT AWAY AT ANY LINGERING LOW CLOUDS
WITH LATER DAY SUNSHINE RESULTING IN UP TO 1500J/KG. NOT EXACTLY
SURE ON THE CONVECTIVE EVOLUTION...BUT ISOLATED TO SCATTERED
STORMS COULD GET FIRED OFF IN UPSLOPE FLOW WITHIN INTERIOR NRN
LOWER WITH THESE STORMS GETTING SHOVED EASTWARD. THIS IS THE ONLY
FORESEEABLE LIFTING MECHANISM (AS WELL AS THE WARM FRONT). THESE
STORMS...WORKING OFF BETTER/DEEPER INSTABILITY...WOULD HAVE A
BETTER SHOT AT PRODUCING SEVERE WEATHER. LARGE HAIL AND DAMAGING
WINDS (AS WIND PROFILES BECOME MORE UNIDIRECTIONAL) WILL BE THE
MAIN THREATS...BUT ANY TIME THERE IS A LINGERING WARM
FRONT/ENHANCED HELICITIES...A TORNADO CANNOT BE RULED OUT.

TONIGHT...CANNOT SEE A TIME TO ELIMINATE CHANCES FOR SHOWERS AND
STORMS. STRONG SHORTWAVE ENERGY DROPS IN OUT OF NE CANADA AND WILL
GRADUALLY ALLOWS THE FRONTAL SYSTEM TO SINK SOUTHWARD. WHILE THE
H8 LLJ IS NOT EXPECTED TO RAMP UP VERY STRONGLY TONIGHT...THE
SOUTH DAKOTA UPPER LOW PIVOTS INTO IOWA AND WILL LIKELY INDUCE SFC
LOW PRESSURE THAT WILL LIFT INTO LOWER MICHIGAN. ENOUGH CONFIDENCE
IN MY UNCERTAINTY ON WHERE EXACTLY THE EXACT FRONTAL/SFC LOW
POSITIONS WILL BE...BUT CAN FORESEE EITHER ANY DIURNAL CONVECTION
BEING HELD TOGETHER INTO THE EVENING...OR THE POSSIBILITY OF IT
FADING AWAY. THERE IS ALSO THE POSSIBILITY FOR LATE NIGHT
NOCTURNAL SHOWERS AND STORMS LIFTING INTO THE M-55 CORRIDOR AHEAD
OF ENERGY EJECTED FROM THE DAKOTA UPPER LOW. LOTS OF
UNCERTAINTY...BUT THEN AGAIN...THERE ALWAYS IS WITH CONVECTION.
INSTABILITY DOESN`T LOOK ALL THAT IMPRESSIVE OVERNIGHT...SO GOTTA
BELIEVE THAT THE BEST SHOT AT SEVERE WEATHER WILL BE TIED TO LATER
THIS AFTERNOON AND INTO THE EVENING.

HIGH TEMPERATURES WILL RANGE FROM THE LOWER 60S IN EASTERN UPPER
(COOLER IF STRATUS/FOG BECOME WIDESPREAD)...TO WELL INTO THE 70S
AND THE LOWER HALF OF THE 80S IN THE MIXED OUT BL ACROSS NRN
LOWER. OF COURSE...COOLER IN EASTERLY FLOW OFF OF LAKE HURON FROM
ROUGHLY M-68 NORTH.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 346 AM EDT TUE MAY 21 2013

WEDNESDAY...BOTH THE GFS AND ECMWF HAVE THE SFC LOW OVER S LOWER,
WITH THE 500 MB LOW TO THE WEST, WITH THE 500 MB JET OVER NE LOWER.
SO THE EXPECTATION IS THAT THE LIKELY AREA OF THUNDERSTORMS WOULD BE
SOUTH AND EAST OF A LINE FROM ALPENA TO MANISTEE. WITH LESS FORCING
IN E UPPER, WOULD EXPECT THAT THE CHANCES ARE MUCH LESS.

WEDNESDAY NIGHT...THE 500 MB TROUGH BEGINS TO MOVE THROUGH THE
FORECAST AREA WITH THE SFC LOW MOVING EAST OF THE REGION. THIS
BRINGS IN LOTS OF COOL DRY AIR WITH THE 70--500 MB LAYER RH FALLING
TO THE SINGLE DIGITS AND THE 850 MB MOISTURE TO AROUND 15%. 850 MB
TEMPERATURES ARE ALSO GOING TO FALL INTO THE SINGLE DIGITS, THAT THE
SET UP FOR THE FOLLOWING DAY, WILL NOW BE CHILLY. ESPECIALLY, SINCE
MOST PEOPLE HAVE GOTTEN USED TO THE 70S AND 80S.

THURSDAY...AS WAS SAID IN THE PREVIOUS PARAGRAPH, THE TEMPERATURES
WILL END UP BEING CHILLY AS THE 850 MB TEMPERATURES APPROACH 0C BY
00Z. THE ONLY THING THAT WE HAVE GOING FOR US WILL BE THE MOSTLY
SUNNY SKY AS THE RH IN THE LOWER AND MID LEVELS OF THE ATMOSPHERE
DRY OUT TO AROUND 10%. THIS WILL ALLOW US TO WARM UNDER FULL SUN.
WITH THE SFC HIGH BUILDING IN THE REGION, WINDS SHOULD BEGIN TO
SETTLE DOWN A BIT AS THE GRADIENT BEGINS TO SLACKEN. OVERNIGHT, AS
THE TEMPERATURES DIP TOWARD FREEZING AND THE WINDS DIMINISH, WILL
EXPECT THAT THE FROST WILL BE AN ISSUE. AT THIS POINT, HAVE PATCHY
AND AREAS OF FROST, BUT IT MAY HAVE TO BE WIDENED AS THE
TEMPERATURES HAVE A CHANCE TO FALL BELOW FREEZING IF CORE OF THE
HIGH SETS UP OVER LIKE THE ECMWF SHOWS.

EXTENDED (FRIDAY THROUGH MONDAY)...FRIDAY, HIGH PRESSURE BUILDS INTO
THE REGION AND KEEPS THE FORECAST AREA DRY. SATURDAY, THE HIGH
PRESSURE REMAINS IN PLACE AND CONTINUES TO KEEP THE PLACE DRY.
SUNDAY, HIGH PRESSURE CONTINUES, SO THE WEEKEND ITSELF LOOKS GOOD
FOR GETTING OUTSIDE. MONDAY, OVER N MICHIGAN LOOKS DRY. IF THE ECMWF
IS RIGHT THEN THE DAY SHOULD TURN OUT MOSTLY SUNNY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 215 PM EDT TUE MAY 21 2013

VFR CONDITIONS DEVELOPING AT THE TAF SITES FOR THE AFTERNOON
HOURS. MAY SEE SOME POP-UP SHOWERS/THUNDERSTORMS AFTER 20Z...THAT
WOULD IMPACT MAINLY APN. OTHERWISE...LIGHT WINDS/MOIST LOW LEVELS
MAY LEAD TO MORE FOG DEVELOPMENT THIS EVENING/OVERNIGHT...ESPECIALLY
AT PLN AND APN.

WEDNESDAY...WAVE OF LOW PRESSURE WILL ADVANCE THROUGH THE REGION
BRINGING ANOTHER BATCH OF SHOWERS AND THUNDERSTORMS TO THE REGION.

&&

.MARINE...
ISSUED AT 346 AM EDT TUE MAY 21 2013

WARM AIR/MOIST OVER COLD LAKE WATERS WILL KEEP WINDS AT BAY...BUT
AREAS OF FOG AND LOW CLOUDS WILL BE SEEN ACROSS MUCH OF NRN LAKE
HURON AND THE STRAITS/LAKE SUPERIOR INTO TODAY. PERIODS OF SHOWERS
AND STORMS WILL BE COMMON AS WELL...DUE TO A NEAR STATIONARY
FRONTAL ZONE STRETCHED OVER NRN LOWER. THIS FRONT WILL DIVE SOUTH
OF US WEDNESDAY...ALLOWING A TIGHTER PRESSURE GRADIENT TO DEVELOP
WEDNESDAY NIGHT THROUGH THURSDAY. AS COLDER AIR POURS IN...THE
STABILITY WEAKENS AND SMALL CRAFT ADVISORY GUSTS LOOK LIKE A GOOD
BET. HIGHER PRESSURE SETTLES IN FRIDAY AND INTO THE WEEKEND.


&&

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

&&

$$

UPDATE...BA
SYNOPSIS...JL
SHORT TERM...SD
LONG TERM...JL
AVIATION...BA
MARINE...SD