Area Forecast Discussion
Issued by NWS Gaylord, MI

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000
FXUS63 KAPX 281105
AFDAPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
605 AM EST SUN DEC 28 2014

.NEAR TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 252 AM EST SUN DEC 28 2014

...COLDER WITH SOME LAKE EFFECT SNOW...

HIGH IMPACT WEATHER POTENTIAL: NOT MUCH. MOSTLY LOW IMPACT LAKE
EFFECT SNOW EXPECTED FOR SOME OF THE TRADITIONAL SNOW BELTS.

PATTERN SYNOPSIS/ANTICIPATED EVOLUTION: STEP-DOWN PROCESS TO A MUCH
COLDER WEATHER REGIME WELL UNDERWAY AT THIS EARLY HOUR. LEAD COLD
FRONT THAT KICKED OFF SUCH CHANGE NOW WELL REMOVED TO OUR
EAST...WITH BACKSIDE CAA WELL ESTABLISHED ACROSS THE NORTHERN
LAKES. NOT EXCEPTIONALLY COLD JUST YET...WITH CURRENT READINGS
MOSTLY IN THE 20S AND LOWER 30S (ACTUALLY...THESE ARE STILL SEVERAL
DEGREES ABOVE NORMAL!). AFTER A BRIEF FLARE UP OF SOME LAKE
INDUCED/TERRAIN ENHANCED LIGHT SNOW SHOWERS THIS PAST EVENING...
CONDITIONS HAVE QUIETED DOWN CONSIDERABLY...OWNING TO CONSIDERABLE
MID LEVEL DRYING SLIDING OVERHEAD (SEE 00Z GREEN BAY SOUNDING).
STILL SOME FLURRIES FLOATING IN OFF THE LAKES...BUT NOTHING
NOTEWORTHY FOR SURE. NEXT SLUG OF "DEEPER" MOISTURE ALREADY
KNOCKING AT THE DOOR...PUNCHING IN ACROSS LAKE SUPERIOR AND THE
NORTHWEST LAKES AHEAD OF PASSING ONTARIO SHORTWAVE AND ATTENDANT
SURFACE TROUGH. MUCH COLDER AIR TUCKING IN BEHIND THIS WAVE...WITH
NEGATIVE MID 20C H8 AIR OVER WESTERN ONTARIO...AND NEGATIVE UPPER
TEENS SLIDING ACROSS NORTHERN MINNESOTA. THIS COLDER AIR WILL BE
HERE SOON ENOUGH...THE CORE OF WHICH ARRIVES TONIGHT INTO THE START
OF THE WORK WEEK. YOU GUESSED IT...TIME TO DUST OFF THE OLD LAKE
EFFECT PLAY BOOK.

PRIMARY FORECAST CHALLENGES/CONCERNS: LAKE EFFECT SNOW
COVERAGE...LOCATION...AND AMOUNTS TODAY AND TONIGHT.

DETAILS: SLOW COOLING PROCESS CONTINUES TODAY AND TONIGHT AS
SOUTHERN EXTENT OF ONTARIO WAVE PASSES ACROSS THE REGION. LAKE
SUPERIOR REINFORCED SURFACE TROUGH SLOWLY SLIDES SOUTHEAST IN
RESPONSE...GRADUALLY WASHING OUT TONIGHT AS MID LEVEL SUPPORT
BECOMES INCREASINGLY DETACHED FROM IT. INITIALLY MARGINALLY
SUPPORTIVE LAKE SURFACE/H8 TEMPERATURE GRADIENT SLOWLY INCREASES
FROM NORTH TO SOUTH AS CAA CONTINUES...WITH SIMPLE DELTA T APPROACH
YIELDING EXCELLENT INSTABILITY ACROSS LAKE SUPERIOR LATER
TODAY...AND ACROSS LAKE MICHIGAN TONIGHT. PERUSAL OF OTHER FACTORS
SAY OTHERWISE...HOWEVER...WITH LAKE MODIFICATION PROCESSES SEVERELY
MUTED BY THINNING UPSTREAM MOISTURE WING AND LIMITED CBL HEIGHTS.
SIMPLE 150+ MILE WNW FLOW FETCH LENGTH ACROSS LAKE SUPERIOR WILL DO
ITS BEST TO COMPENSATE SUCH DEFICIENCIES. SAME CANNOT BE SAID FOR
NORTHERN LOWER WITH VAST AMOUNT OF DRY AIR ABOVE SAID SHALLOW
INVERSION NEGATING MUCH...IF ANY...LAKE SUPERIOR CONTRIBUTION.
BREAKING DOWN THE LAKES:

OFF LAKE SUPERIOR: DEFINITELY GOING TO SNOW IN THE TRADITIONAL SNOW
BELTS. "HEAVIEST" ACTIVITY LIKELY TO OCCUR FOR A SHORT WINDOW LATER
THIS MORNING OR EARLY AFTERNOON AS EARLIER MENTIONED SURFACE
TROUGH/CORRIDOR OF ENHANCED CONVERGENCE DROPS SOUTH OFF LAKE
SUPERIOR. MULTI-BANDED WNW TO NW LAKE SNOWS EXPECTED THEREAFTER
THROUGH TONIGHT. SOME HINTS OF A RETURN OF ENHANCED LOW LEVEL
CONVERGENCE OVERNIGHT AS DRAINAGE FLOW FROM ONTARIO BUBBLE HIGH
DEVELOPS. NOT EXACTLY SURE HOW STRONG THIS NORTHEAST FLOW WILL
BE...BUT DEFINITELY WOULD NOT BE SURPRISED IF IT MANAGED TO PUSH
BANDS WEST OF THE SOO BY LATER TONIGHT. EITHER WAY...JUST NOT
LOOKING AT A SIGNIFICANT SNOW EVENT GIVEN TRANSIENT NATURE OF
ENHANCED SNOWS THIS MORNING AND LIMITED LAKE INDUCED CONVECTIVE
LAYER TONIGHT (SUB 5KFT). LAKE CLOUDS WELL ALIGNED WITH FAVORABLE
DGZ...SUGGESTING SOME DECENT TO EXCELLENT SNOW/LIQUID RATIOS.
OVERALL...EXPECTING A GENERAL 2 TO 4 INCHES OF FLUFF BY SUNRISE
MONDAY IN THE LAKE ZONES...WITH LOCALLY HIGHER AMOUNTS POSSIBLE
WHERE CONVERGENCE IS MAXIMIZED TONIGHT. SHORT OF ANY HEADLINE
CRITERIA...BUT DEFINITELY CAPABLE OF PRODUCING SOME SNOW COVERED AND
SLICK ROADS.

OFF LAKE MICHIGAN: A MUCH DIFFERENT STORY...WITH EVEN LOWER
INVERSION HEIGHTS AND NOTED INVERTED V SIGNATURE IN THE LOW LEVELS.
UPSTREAM MOISTURE THINS CONSIDERABLY...LIKELY ENOUGH SO TO NEGATE A
SIGNIFICANT INFLUENCE ON LOWER LEVEL LAKE PROCESSES. PERHAPS SOME
FLURRIES/VERY LIGHT SNOW SHOWERS TODAY IN WEST FLOW AREAS...WITH
ACCUMULATIONS REMAINING MINIMAL...IF ANY AT ALL. WINDS VEER
NORTHWEST THIS EVENING WITH PASSAGE OF SUBTLE SURFACE TROUGH. BRIEF
WINDOW OF ENHANCED CONVERGENCE MAY TIP THE SCALES TO SOME MORE
RESPECTABLE SNOW SHOWERS BEFORE COMPLETE LACK OF SYNOPTIC SCALE
MOISTURE AND DEVELOPMENT OF ANTICYCLONIC LOW LEVEL FLOW TAKE THEIR
COLLECTIVE TOLL. SIMPLE EXTREME GRADIENT OF WATER/AIR TEMPERATURE
WILL NO DOUBT KEEP SOME LIGHT ACTIVITY GOING IN NORTHWEST FLOW
AREAS. UPSHOT TO THE ABOVE...REALLY THINK TOTAL ACCUMULATIONS
THROUGH TONIGHT WILL REMAIN LARGELY UNDER AN INCH...WITH ANY HIGHER
AMOUNTS (UP TO 2 INCHES?) FEW AND FAR BETWEEN.

MAINLY CLOUDY SKIES WITH A FEW FLURRIES EXPECTED AWAY FROM THE
TRADITIONAL LAKE BELTS TODAY AND TONIGHT. TEMPERATURES WILL BE
NOTICEABLY COLDER...MOSTLY IN THE UPPER 20S AND LOWER 30S
TODAY...AND IN THE TEENS/LOWER 20S TONIGHT.

&&

.SHORT TERM...(MONDAY THROUGH TUESDAY NIGHT)
ISSUED AT 252 AM EST SUN DEC 28 2014

COLD AIR MORE THAN SUFFICIENT FOR LAKE SNOW
PRODUCTION (850 MB TEMPS OF -17 TO -22 C) WILL REMAIN IN PLACE OVER
THE NRN GREAT LAKES DURING THE FIRST PART OF THE WORK WEEK.
HOWEVER...INVERSION HEIGHTS WILL HOLD AROUND 5-6 KFT THRU MONDAY...
WITH ANY AVAILABLE SYNOPTIC MOISTURE REMAINING UNDER THE INVERSION.
NW LOW LEVEL WINDS ON MONDAY WILL SHIFT TO THE WEST ON TUESDAY...
THUS TARGETING THE TYPICAL SNOWBELT REGIONS OF ERN UPR AND NW/N
CENTRAL LWR MICHIGAN FOR THE HIGHEST POPS AND GREATEST POTENTIAL FOR
ACCUMULATIONS. HOWEVER...STRONG SURFACE RIDGING WILL BUILD INTO THE
GREAT LAKES DURING THIS TIME. STRONG SUBSIDENCE COMBINED WITH
RATHER SHALLOW INSTABILITY AND MOISTURE WILL LEND TO RATHER LIGHT
NEW SNOW ACCUMULATIONS AROUND AN INCH OR SO FOR EACH FORECAST PERIOD
THRU TUESDAY). HIGH TEMPS BOTH MONDAY AND TUESDAY WILL ONLY WARM
INTO THE UPPER TEENS TO LOWER 20S. LOW TEMPS MONDAY NIGHT AND
TUESDAY NIGHT WILL FALL INTO THE SINGLE DIGITS ABOVE ZERO TO THE LOW
TO MID TEENS.

&&

.LONG TERM...(WEDNESDAY THROUGH SATURDAY)
ISSUED AT 252 AM EST SUN DEC 28 2014

STRONG RIDGE AXIS WILL SAG SOUTH INTO THE
OHIO VALLEY BY WEDNESDAY AND THEN INTO THE SE US THURSDAY AND
FRIDAY. BROAD TROUGHING WILL DIG SOUTH INTO THE UPPER MID WEST AND
THE GREAT LAKES DURING THIS TIME. OVER-LAKE INSTABILITY WILL REMAIN
MORE THAN SUFFICIENT FOR CONTINUED LAKE SNOW PRODUCTION THRU THE
REMAINDER OF THE WEEK...PERIODICALLY ENHANCED BY A SERIES OF SHORT
WAVES RIDING THRU THE BASE OF THE BROAD TROUGH. ECMWF IS STILL
SHOWING A RATHER STRONG SRN STREAM LOW LIFTING OUT OF THE GULF OF
MEXICO AND INTO THE NE US ON SATURDAY...BUT THE EXACT TRACK IS
CERTAINLY UNCLEAR AT THIS TIME. TEMPS WILL SLOWLY MODERATE THRU THIS
PERIOD. AFTERNOON HIGHS IN THE TEENS ON WEDNESDAY WILL WARM INTO THE
MID 20S TO LOWER 30S BY SATURDAY. OVERNIGHT LOWS WILL BE MAINLY IN
THE TEENS THRU THIS PERIOD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 605 AM EST SUN DEC 28 2014

LIGHT LAKE EFFECT SNOW SHOWERS WILL GRADUALLY INCREASE IN
FREQUENCY AS COLDER AIR FILTERS INTO THE REGION THRU TONIGHT.
OVERALL VSBYS ARE EXPECTED TO REMAIN VFR...WITH MAINLY MVFR CIGS
THRU TONIGHT. WEST WINDS AROUND 10 KTS WILL SHIFT TO THE NW
TONIGHT.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR LHZ345>348.

LM...SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR LMZ342-344.

LS...SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR LSZ321-322.

&&

$$

NEAR TERM...MSB
SHORT TERM...MLR
LONG TERM...MLR
AVIATION...MLR


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