Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 010536
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
136 AM EDT WED APR 1 2015

.UPDATE...
ISSUED AT 950 PM EDT TUE MAR 31 2015

AN INTERESTING EVENING. DECAYING LOW PRESSURE IN E CENTRAL WI (SW
OF GRB) HAS JUST ABOUT OPENED UP INTO A TROF AXIS.
HOWEVER...PRECIP CONTINUES E AND NE OF THIS FEATURE...ENHANCED BY
STEEP MID-LEVEL LAPSE RATES AND F-GEN FORCING. 00Z APX SOUNDING
HAD A NEAR-SATURATED LAYER BETWEEN 725 AND 600MB...WITH NEAR DRY-
ADIABATIC LAPSE RATES FROM THE TOP OF THAT LAYER UP TO ALMOST
500MB.

AN AREA OF CONVECTIVE PRECIP...MIXED RAIN/SNOW SHOWERS...IS
SWINGING THRU NW LOWER MI PRESENTLY. THIS WILL BE A QUICK SHOT AND
NOT HAVE MUCH OF ANY IMPACT. BUT POPS WERE INTRODUCED/EXPANDED
THERE.

THE MORE SUBSTANTIAL FEATURE OF NOTE IS A NARROW BAND OF FGEN-
ENHANCED SNOW FROM WESTERN MACKINAC CO TO NEAR HARRISVILLE. THE
BACK EDGE OF THIS IS ADVANCING NORTHWARD ACROSS EASTERN
UPPER...WHERE PRECIP INTENSITY IS ALREADY STARTING TO DIMINISH.
ACCUMS OF AROUND 2 INCHES HAVE BEEN REPORTED IN ENGADINE AND
MACKINAW CITY...THOSE AREAS WILL NOT SEE MUCH MORE. HEAVIER/MORE
PERSISTENT SNOW HAS BEEN FALLING IN CENTRAL/NORTHERN CHEBOYGAN
CO...THOUGH THIS NARROW BAND HAS BEEN DRIFTING EASTWARD WITH TIME.
MID-30S DBZ RETURNS ARE COMMON IN THIS AREA...STRONG SUPPORTING
BETTER THAN 1 INCH/HR SNOWS.

SPS WAS ISSUED EARLIER TO ADDRESS THIS. IF THIS WAS GOING TO LAST
FOR MORE THAN ANOTHER HOUR I WOULD POP AND ADVISORY FOR CHEBOYGANAND
PERHAPS SW PRESQUE ISLE. BUT THE INTENSITY WILL FALL OFF RAPIDLY
AFTER 1030 PM. WILL INSTEAD LIVE WITH A SMALL AREA OF EXPECTED 3-5
INCH ACCUMS IN CENTRAL/NORTHERN CHEBOYGAN...FOREGO A
HEADLINE...AND REFRESH THE SPS LATER THIS EVENING.

&&

.NEAR TERM...(THIS EVENING THROUGH TONIGHT)
ISSUED AT 354 PM EDT TUE MAR 31 2015

ON THE LATEST SURFACE WEATHER MAP...1002 MB LOW PRESSURE WAS OVER
SOUTH CENTRAL PENNSYLVANIA AND 1009 MB LOW PRESSURE WAS OVER
CENTRAL LAKE SUPERIOR. SATELLITE IMAGERY AND SURFACE OBSERVATIONS
SHOWED LOW CLOUDS FROM THIS MORNING HAD ABOUT DISSIPATED WHILE MID
AND HIGH CLOUDS WERE INCREASING FROM THE SYSTEM APPROACHING FROM
THE NORTHWEST. THE APX AND UPSTREAM CANADIAN RADARS SHOWED
INCREASING RETURNS. FORECAST CONCERNS INCLUDE THE TIMING IN AND
THE TIMING OUT OF PRECIPITATION AND PRECIPITATION TYPE THIS
EVENING INTO EARLY TONIGHT.

THE WEAK WAVE EVIDENT ON WATER VAPOR IMAGERY DROPPING DOWN THROUGH
THE FLOW ALONG WITH ASSOCIATED ISENTROPIC ASCENT AND DECENTLY STEEP
MID LEVEL LAPSE RATES LOOK LIKE THEY WILL COMBINE TO BRING A PERIOD
OF SNOW TO EASTERN UPPER AND FAR NORTHERN LOWER MICHIGAN THIS
EVENING INTO EARLY TONIGHT. THINK PRECIPITATION WILL BE MAINLY IN
THE FORM OF ALL SNOW DUE TO EVAPORATIVE COOLING FROM VERY DRY LOW
LEVELS (MODEL SOUNDINGS SUPPORT THIS IDEA) SO HAVE PULLED OUT THE
CHANCE FOR RAIN. SOME SPOTS COULD SEE A FRESH COATING OF SNOW WITH
A TOP END SNOW ACCUMULATION FORECAST TO BE ABOUT AN INCH.
ELSEWHERE ACROSS SOUTHWEST ZONES...ONLY CLOUDS ARE EXPECTED. WINDS
WILL BE LIGHT OUT OF THE NORTHEAST THEN VEER INTO THE EAST AFTER
MIDNIGHT. LOWS WILL BE MAINLY IN THE 20S.

&&

.SHORT TERM...(WEDNESDAY THROUGH FRIDAY)
ISSUED AT 354 PM EDT TUE MAR 31 2015

...RAIN AND A FEW STORMS WEDNESDAY NIGHT-THURSDAY...

HIGH IMPACT WEATHER POTENTIAL: A FEW THUNDERSTORMS ARE POSSIBLE
WEDNESDAY NIGHT THROUGH EARLY THURSDAY.  NO SEVERE WEATHER IS
EXPECTED.  OTHERWISE NIL.

PATTERN/FORECAST: TIME-LONGITUDE PLOTS SHOW AN IMPRESSIVE
PERSISTENCE TO RIDGING NEAR 120W SINCE THE BEGINNING OF THE CALENDAR
YEAR...WITH DOWNSTREAM TROUGHING CENTERED A LITTLE EAST OF THE GREAT
LAKES...RESULTING IN OUR PERSISTENT COOL /AND RELATIVELY DRY/
PATTERN SO FAR THIS YEAR.  THE PATTERN EARLY THIS AFTERNOON IS IN
PRETTY GOOD AGREEMENT WITH THE RECENT TREND...WITH RIDGING CENTERED
ALONG THE SPINE OF THE ROCKIES (A BIT EAST OF IT/S TIME-AVERAGED
LOCATION) WITH TROUGHING CENTERED OVER THE NORTHEASTERN STATES.
LOOKING FORWARD INTO THE SHORT TERM FORECAST PERIOD...ROBUST
TROUGHING ALONG THE WEST COAST OF NOAM WILL PROVIDE FOR AT LEAST A
TEMPORARY BREAK DOWN OF THE WESTERN RIDGE...STEADILY PUSHING EAST
AND THROUGH THE GREAT LAKES REGION /WED NIGHT-THU/...WITH SHORTWAVE
RIDGING PRECEDING THIS FEATURE EXPECTED TO ARRIVE ON WEDNESDAY.
SO...A CHANGEABLE PERIOD OF WEATHER IS EXPECTED THROUGH THE SHORT
TERM...WITH A MODERATION IN TEMPERATURES FOLLOWED BY A PERIOD OF
PRECIPITATION AS THE UPSTREAM SHORTWAVE ARRIVES FROM THE WEST.
FINALLY...WITH TROUGHING MOVING BACK OVERHEAD TO END THE PERIOD
FRIDAY...A RETURN TO WHAT WE HAS BEEN "NORMAL" SO FAR THIS YEAR WITH
COOLER THAN NORMAL TEMPERATURES AND DRIER CONDITIONS.

WEATHER:

WEDNESDAY: HIGH PRESSURE NOSES IN FROM THE NORTH AS SHORTWAVE RIDGE
AXIS PASSES OVERHEAD.  AS MENTIONED BY THE PREVIOUS FORECASTER...
THERE ARE CONCERNS ABOUT RESIDUAL LLEVEL CLOUDINESS AT LEAST IN THE
MORNING WITH WEAK/NON-EXISTENT LLEVEL FLOW AND RESIDUAL LLEVEL
MOISTURE BEHIND SECONDARY WAVE THAT MOVES ACROSS THE REGION TONIGHT.
AT THE SAME TIME...DEVELOPING WARM ADVECTION ALOFT ON THE BACK SIDE
OF RETREATING SHORTWAVE RIDGING PROMISES A GOOD DEAL OF MID AND
UPPER LEVEL CLOUDINESS INCREASING THROUGH THE DAY.  I DO EXPECT THAT
THE LLEVEL CLOUDINESS WILL THIN/BREAK UP /EVEN THE TYPICALLY
OVERDONE NAM THINS THE LLEVEL MOISTURE DURING THE DAY...BUT... AS A
WHOLE EXPECT THAT WE/LL SEE MORE CLOUDS THAN SUN AS THE MID/UPPER
LEVEL CLOUDS TEMPER ANY CLEARING.  ONLY POTENTIAL FOR DEVELOPING
WARM ADVECTION TO SPAWN ANY PRECIPITATION WILL BE OVER EASTERN
UPPER...WHERE MOISTURE WILL BE DEEPEST.  EVEN HERE...H9-8 DRY WEDGE
REMAINS RATHER ROBUST...WITH LLEVEL TRAJECTORIES SOUTHEAST THROUGH
EVENING...SO NO HIGHER THAN INHERITED CHANCE POPS WARRANTED AT THIS
TIME.

WEDNESDAY NIGHT-THURSDAY: GOOD DETERMINISTIC/ENSEMBLE AGREEMENT ON
APPROACHING SHORTWAVE AND ASSOCIATED SURFACE LOW PASSING NORTH OF
THE REGION THROUGH THIS PERIOD.  WARM ADVECTION REGIME IN PLACE
WEDNESDAY NIGHT WITH A STRONG SURGE OF LLEVEL MOISTURE AFTER
MIDNIGHT...SPIKING PWATS TO AROUND ONE INCH /RIGHT AT RECORD LEVELS
FOR THE START OF APRIL/.  DESPITE ONLY MODEST FORCING AT MID LEVELS
/BEST MID LEVEL QG SUPPORT NORTH OF THE LAKES CLOSER TO PARENT WAVE/
LLEVEL JET-INDUCED MOISTURE SURGE AND ISENTROPIC ASCENT SHOULD HAVE
NO PROBLEM EXPANDING A SHIELD OF RAIN FROM NORTHWEST TO SOUTHEAST
ACROSS THE REGION WEDNESDAY NIGHT THROUGH EARLY MORNING THURSDAY.
SHOWALTER INDICES DROP BELOW ZERO AFTER MIDNIGHT GIVEN ROBUST LLEVEL
HEAT/MOISTURE TRANSPORT...AND A SLIGHT CHANCE OF THUNDER CONTINUES
TO BE WARRANTED.

COLD FRONT ARRIVES ON THURSDAY...WITH ADDED SUPPORT OF RIGHT
ENTRANCE REGION SUPPORT AT H2.  THIS WILL TAKE RAIN SHIELD AND PUSH
IT EAST THROUGH THE REMAINDER OF THE FORECAST AREA DURING THE
MORNING/EARLY AFTERNOON. EXACT TIMING WILL DETERMINE HOW MUCH
HEATING WE CAN ACHIEVE IN THE PREFRONTAL AIRMASS...WHICH MAY ALLOW
FOR SOME SURFACE BASED INSTABILITY TO DEVELOP.  CERTAINLY SOME
POTENTIAL TO PUSH MUCAPES TO NEAR 500 J/KG OVER NORTHEAST
LOWER...AND WILL CONTINUE THUNDER MENTION AS A RESULT.  WILL NEED TO
SEE A TREND TO MORE INSTABILITY /GIVEN SUBSTANTIAL 60KT DEEP SHEAR/
BEFORE ANY WORRIES ABOUT A SEVERE THREAT /SEE SPC MARGINAL RISK
SOUTH OF OUR AREA/ BUT THIS PERIOD IS CERTAINLY WORTH WATCHING AND
CAN/T RULE OUT A FEW SMALL HAILSTONES IN ANY STORMS THAT DEVELOP.

AS FOR QPF...ENSEMBLE CONSENSUS WOULD FAVOR CLOSER TO ONE HALF INCH
EASTERN UPPER/COAST OF NW LOWER...TAPERING TO 0.25" OVER NORTHEAST
LOWER.  THE POTENTIAL FOR EMBEDDED CONVECTION ALWAYS THROWS A CAVEAT
IN...WITH A FEW LOCATIONS LIKELY TO SEE A BIT HIGHER THAN THESE
AMOUNTS...BUT NOTHING TOO OUT OF CONTROL FOR EARLY APRIL AND QPF
CONTINGENCY FORECASTS SUGGEST THAT EVEN WITH AMOUNTS ON THE HIGH
SIDE OF THE GUIDANCE ENVELOPE WOULD STILL KEEP AREA RIVERS IN/NEAR
BANKFULL.

FRIDAY: ROBUST COLD ADVECTION BEHIND DEPARTING COLD FRONT TAKES T8S
BACK TOWARDS -10C DURING THE DAY UNDER A MODERATE NORTHWESTERLY
GRADIENT. THERE IS SOME RESIDUAL LLEVEL MOISTURE...AND GIVEN THAT
THE CLOUD-BEARING LAYER WILL RESIDE CLOSE TO -10-12C...COULD SEE A
FLURRY OR TWO...MOST LIKELY OVER EASTERN UPPER WHERE LLEVEL TEMPS
WILL BE COOLEST.  OTHERWISE...PARTLY SUNNY SKIES SHOULD RULE THROUGH
MUCH OF THE DAY BEFORE EYES TURN SOUTH TO POTENTIAL DEVELOPING LOW
PRESSURE ALONG STALLED FRONTAL BOUNDARY TO OUR SOUTH.  MORE ON THIS
IN THE LONG TERM SECTION BELOW...BUT WILL INTRODUCE CHANCE POPS OVER
FAR SOUTHEASTERN ZONES FRIDAY AFTERNOON /FOR RAIN DURING THE DAY/
GIVEN NORTHWARD MOVEMENT OF GUIDANCE CONSENSUS.

TEMPERATURES:

CLOUD COVER WILL CERTAINLY PLAY A ROLE IN TEMPERATURES ON WEDNESDAY
WITH VERTICAL MIXING LIMITED SOMEWHAT BY NEARBY HIGH TO THE NORTH.
T9S WARM ABOVE FREEZING TOWARDS EVENING...WHICH...FULLY MIXED WOULD
ALLOW LOCATIONS OVER NORTHWEST LOWER TO REACH INTO THE 50S.  GIVEN
HIGH LOCATION...EXPECT EASTERN UPPER AND NE LOWER WILL STRUGGLE TO
WARM...AND REMAIN IN THE 40-45F RANGE...WITH THE REMAINDER OF
NORTHERN LOWER REACHING ABOVE 50...AND PERHAPS NEAR 55F GIVEN
DEVELOPING DOWNSLOPING WEST OF US-131. WARM NIGHT WEDNESDAY NIGHT
WITH NON-DIURNAL TEMPERATURE CURVE AS LLEVEL SOUTHERLY GRADIENT
KEEPS THE LLEVELS COUPLED...AND INCREASING CLOUDS/PRECIPITATION
PRECLUDE MUCH RADIATIONAL HEAT LOSS.  EXPECT TEMPERATURES TO FALL
SOME IN THE EVENING...BUT STEADY...AND LIKELY RISE OVERNIGHT...WITH
TEMPERATURES DAYBREAK THURSDAY NEAR 40 EASTERN UPPER/NE LOWER...AND
IN THE 40S ELSEWHERE.

CHALLENGING TEMPERATURE FORECAST THURSDAY THERMAL RIDGE OVERHEAD AT
DAYBREAK AND SHIFTING EAST DURING THE DAY.  T9S NEAR +10C SUPPORT
LOCATIONS REACHING 60F WITH SOME LLEVEL MIXING.  BEST CHANCE FOR
THIS WILL BE NORTHEAST LOWER...WHERE LLEVEL DOWNSLOPING
/SOUTHWESTERLY WINDS/ SHOULD KEEP PRECIPITATION AT BAY THE LONGEST
AND PROMOTE THE GREATEST MIXING.  12Z HIGH RES GUIDANCE CONTINUES TO
SUPPORT HIGHS AROUND 60 IN THESE SPOTS...WHICH APPEARS REASONABLE.
PRETTY LARGE GRADIENT TO THE WEST...HOWEVER...WITH ONGOING
PRECIPITATION AND FALLING LLEVEL TEMPERATURES KEEPING A LID ON
TEMPERATURES IN THESE LOCATIONS...WITH HIGHS LIKELY STUCK IN THE
UPPER 40S TO LOWER 50S.  ACTUAL GRADIENT WILL PROBABLY BE SHARPER
THAN WE CAN CONFIDENTLY DEPICT IN THE FORECAST TODAY.

BACK TO WHAT WE HAVE BEEN USED TO ON FRIDAY WITH TEMPERATURES ONLY
SLOWLY CLIMBING AGAINST ONGOING COLD ADVECTION.  T9S IN THE MINUS
SINGLE DIGITS SPELL HIGHS RANGING FROM NEAR THE FREEZING MARK
EASTERN UPPER TO AROUND 40 SOUTH OF M-32.

&&

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 354 PM EDT TUE MAR 31 2015

THE PERIOD STARTS WITH BROAD UPPER-LEVEL TROUGHING ACROSS THE
EASTERN THIRD OF THE CONUS AND A GULF OF MOISTURE-RICH LOW PRESSURE
SYSTEM MOVING THROUGH THE OHIO VALLEY NORTHEASTWARD INTO THE
NORTHEAST FRIDAY NIGHT. WILL HAVE TO CONTINUE TO MONITOR THE GRADUAL
NORTHWARD SHIFT OF THE PRECIP SHIELD NOTED OVER THE PAST 24 HOURS OR
SO IN NEARLY ALL GUIDANCE. AT THIS POINT WILL GO AHEAD AND INTRODUCE
CHANCE POPS OVER SOUTHEASTERN PORTIONS OF THE CWA ENDING BY 12Z
SATURDAY. HOT ON ITS HEELS...BY SATURDAY EVENING...ANOTHER SHORTWAVE
APPROACHES FROM THE NORTHWEST AND WITH TEMPS BELOW 0C THROUGHOUT THE
COLUMN AT THAT POINT...COULD SEE A WINDOW WITH SCATTERED LIGHT SNOW
SHOWERS OVER PARTS OF THE AREA LATE EVENING INTO THE OVERNIGHT HOURS
SATURDAY NIGHT. THE REMAINDER OF THE WEEKEND...INCLUDING THE EASTER
HOLIDAY...LOOKS TO FEATURE RATHER CHILLY TEMPERATURES AND PERHAPS A
BIT OF ADDITIONAL LIGHT PRECIP...ESPECIALLY ACROSS SOUTHERN AREAS.

EARLY NEXT WEEK...GLOBAL MODEL GUIDANCE CONTINUES TO HINT AT LOW
PRESSURE (ABLE TO TAP INTO GULF MOISTURE - SOMETHING NOT SEEN MUCH
UP NORTH THIS WINTER) DEVELOPING OVER THE PLAINS BY MONDAY
...THEN TRACKING INTO THE UPPER MIDWEST/GREAT LAKES REGION FOR
TUESDAY-WEDNESDAY. AS MENTIONED YESTERDAY...WILL NOT ATTEMPT TO GET
TOO SPECIFIC WITH DETAILS AS THE PLACEMENT OF THE BAROCLINIC ZONE
WELL AHEAD OF THE SYSTEM ON MONDAY ALONG WITH EXACT TIMING AND
PLACEMENT OF THE DEVELOPING LOW (AND THE FACT THAT IT DEVELOPS AS
PROGGED) WILL DETERMINE WHETHER WE ARE DEALING WITH RAIN AND THUNDER
CHANCES OR A WIDESPREAD WINTRY EVENT - ALL CERTAINLY WITHIN THE
SPECTRUM OF POSSIBILITIES AT THIS POINT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 135 AM EDT WED APR 1 2015

PERIODS OF IFR/LIFR CONDITIONS EXPECTED AT PLN TONIGHT INTO EARLY
WEDNESDAY MORNING...WITH CONDITIONS TRENDING TOWARD MVFR AT APN
OVERNIGHT INTO WEDNESDAY MORNING. WILL WATCH FOR FOG POTENTIAL AT
TVC/MBL...PERHAPS SOME MVFR VISIBILITIES AT TVC FOR A TIME
OVERNIGHT.

&&

.MARINE...
ISSUED AT 354 PM EDT TUE MAR 31 2015

WEAK GRADIENT TONIGHT AS LOW PRESSURE SLIDES BY THE AREA YIELDING
PREDOMINATELY LIGHT NORTHEAST WINDS WHICH SHOULD VEER INTO THE EAST
LATE. INCREASING SOUTHEAST GRADIENT ON WEDNESDAY...MAY LEAD TO SMALL
CRAFT ADVISORIES WEDNESDAY NIGHT INTO THURSDAY.


&&

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

$$

UPDATE...JAZ
NEAR TERM...SULLIVAN
SHORT TERM...ARNOTT
LONG TERM...GILLEN
MARINE...SULLIVAN


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