000
FXUS63 KAPX 070840
AFDAPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
340 AM EST WED JAN 7 2009
.SYNOPSIS.../ISSUED AT 340 AM/
A STRENGTHENING STORM SYSTEM WILL LIFT THROUGH THE EASTERN GREAT
LAKES TODAY AND INTO UPSTATE NEW YORK TONIGHT. OCCASIONAL SNOWS WILL
CONTINUE TO AFFECT ALL OF NORTHERN MICHIGAN THROUGH THE DAY AND AT
LEAST THE EVENING. LIGHT AMOUNTS OF SNOW WILL FALL...HOWEVER A FEW
AREAS WILL SEE HEAVIER AMOUNTS. WHILE THE STORM EXITS TO OUR EAST
LATE TONIGHT...LAKE EFFECT SNOWS WILL CONTINUE TO AFFECT THE
SNOWBELTS. THESE SNOWS WILL PERSIST THROUGH THURSDAY NIGHT WITH
ADDITIONAL ACCUMULATIONS ANTICIPATED. THE SNOW WILL TAPER OFF LATE
THURSDAY NIGHT AND FRIDAY...BEFORE AN ALBERTA CLIPPER WILL QUICKLY
ARRIVE FRIDAY AFTERNOON FOR POTENTIALLY MORE ACCUMULATING SNOW.
SMD
&&
.SHORT TERM.../ISSUED AT 340 AM/...TODAY
LATEST SNOW EVENT UNDERWAY ACRS THE REGION THIS MORNING...THE RESULT
OF INCREASING MID LEVEL ISENTROPIC ASCENT AHEAD OF NORTHERN/SOUTHERN
STREAM WAVES SLOWLY BEGINNING TO PHASE ACRS THE MID MISS VALLEY. SFC
PRESSURE PATTERN REFLECTS A DEEPENING RESPONSE INTO THE OHIO
VALLEY...WITH 995MB SFC LOW DEPICTED NEAR MARION OH AS OF 06Z AND
PEGGED TO TAKE A JAUNT TO LAKE ERIE THIS MORNING. WHILE NORMALLY A
GREAT SETUP FOR SNOW ACRS THE REGION...MOISTURE SEVERELY LACKING
GIVEN GULF CUTOFF PER DEVELOPING DEEP CONVECTION AND BEST MOISTURE
TRANSPORT WELL INTO THE MID ATLANTIC (SEE ONGOING HEAVY RAINS ACRS
THAT REGION). WHAT WE`RE LEFT WITH IS MORE TYPICAL STUFF...WITH
850-700MB SPECIFIC HUMIDITY VALUES OF 2-3G/KG SUPPORTING A GENERAL 1
TO 3 INCHES OF SNOW ACRS THE CWA THRU THE DAY AS LOW/MID LEVEL
TROWAL AXIS PIVOTS THRU NORTHERN MICHIGAN.
THAT SAID...ALREADY ONE SURPRISE EARLY THIS MORNING AS LEAD
SHORTWAVE EJECTING ACRS LAKE MICHIGAN ACTING TO TIGHTEN 750-650MB
FGEN RESPONSE...RESULTING IN A RATHER HEALTHY SNOW BAND ACRS
NORTHWEST LOWER (THOUGH STILL SOME DRY AIR ISSUES DOWN LOW). PER 00Z
NAM12...FGEN FORCING AXIS SHOULD SLIP ACRS NORTHERN LOWER THRU 12Z
BEFORE GRADUALLY WEAKENING...THOUGH CERTAINLY WORTH KEEPING AN EYE
ON FOR THE MORNING. HOISTING OF ADVISORY ON PREVIOUS EVENING SHIFT
FOR LOCALIZED LAKE ENHANCEMENT STILL APPEARS WARRANTED FOR A FEW
COUNTIES ACRS NORTHEAST LOWER WHERE LOW LEVEL TRAJECTORIES HOLD OUT
OF THE E/NE THRU EARLY AFTN WHILE OVERLAKE INSTABILITY SUFFICIENT
GIVEN H85 TEMPS AROUND -10C...LIKELY SUFFICIENT FOR A FEW INCHES OF
SNOW. ELSEWHERE...JUST MORE OF A "NORMAL" SNOWY DAY ACRS NORTHERN
MICHIGAN - MAINLY 1 TO 3 INCHES EXPECTED.
LAWRENCE
&&
.LONG TERM.../ISSUED AT 340 AM/...TONIGHT AND BEYOND
BIGGEST CHALLENGE REVOLVES AROUND LAKE EFFECT CHANCES THRU THURSDAY
FOLLOWED BY ADDITIONAL SNOW CHANCES HEADING TOWARD THE WEEKEND AS A
SERIES OF CLIPPER SYSTEMS DROP INTO THE GREAT LAKES. EXPECT
LINGERING LIGHT SNOW ACRS THE REGION TO SLOWLY DISSIPATE THRU THE
LATE EVENING/OVERNIGHT HOURS AS BRIEF SHOT OF DEFORMATION DYNAMICS
WEAKENS...ONLY TO BE REPLACED BY DEVELOPING LAKE EFFECT SNOW SHOWERS
AS LOW LEVEL FLOW BECOMES N/NW. PARAMETERS NOT TOO SHABBY WITH DELTA
T`S AROUND 15C WHILE 850-700MB RH WELL ABOVE 80% THRU THURSDAY AND
INVERSION HEIGHTS AROUND 800MB. HOWEVER...GRADUAL DEVELOPMENT OF
UPSTREAM ANTICYCLONIC FLOW REGIME INTO THU MORNING/AFTN MEANS LOSS
OF INITIAL LAKE SUPERIOR CONNECTION AND ALSO SOME SPREADING OUT OF
SNOWFALL. COULD FORESEE EVENTUAL NEED FOR A HEADLINE WITH PERHAPS
2-4/3-5 ACRS PORTIONS OF NORTHWEST LOWER...THOUGH CONFIDENCE
SUFFICIENTLY LOW AT THIS POINT TO HOLD OFF.
LINGERING ACTIVITY SHOULD SLOWLY WIND DOWN INTO THU NIGHT AS
MOISTURE QUICKLY WANES AND INVERSION HEIGHTS FALL TO AROUND 900MB
WITH APPROACH OF SHORTWAVE RIDGING. HOWEVER...BREAK SHORT-LIVED AS
NEXT PIECE OF PACIFIC ENERGY ON TRACK TO ARRIVE AS A CLIPPER SYSTEM
FRI/FRI NIGHT TIMEFRAME. 00Z GUIDANCE STILL JUMPING ALL OVER THE
PLACE WITH REGARD TO PLACEMENT OF SFC RESPONSE AND BEST PLACEMENT OF
PRECIP SHIELD...AND GIVEN SPLITTING NATURE OF WESTERN SYSTEM FULLY
EXPECT ADDITIONAL CHANGES BEFORE SYSTEM GETS ASHORE. WILL THUS KEEP
GOING LIKELY POPS INTACT...WITH THE POTENTIAL FOR A RATHER QUICK-
HITTING MODEST SNOW EVENT. THEREAFTER...A RETURN TO LAKE EFFECT INTO
SAT/SAT NIGHT BEFORE PERHAPS NEXT CLIPPER SYSTEM ARRIVES SOMETIME
SUN/MON (WILL LEAVE THAT ONE FOR THE DAY SHIFT).
LAWRENCE
&&
.MARINE.../ISSUED AT 340 AM/
WILL HOIST SMALL CRAFT ADVISORIES ON THE LAKE HURON SIDE OF
NORTHEAST LOWER AS INCREASING GRADIENT COUPLED WITH OVERLAKE
INSTABILITY LIKELY SUFFICIENT TO PRODUCE SOME GUSTS IN EXCESS OF 25
KNOTS THRU THE DAY. IN ADDITION...PERSISTENT E/NE FETCH SHOULD HELP
BUILD SOME WAVES IN EXCESS OF 4 FEET...LIKELY PERSISTING THRU
TONIGHT. ADDITIONAL SMALL CRAFT ADVISORY CONDITIONS LIKELY THU AND
BEYOND AS SEVERAL WEATHER SYSTEMS ROLL THRU THE AREA.
LAWRENCE
&&
.AVIATION.../ISSUED AT 1150 PM/...VALID FOR 06Z TAFS
SNOW WILL DEVELOP AT ALL TAF SITES OVER THE NEXT FEW HOURS...AS LOW
PRESSURE SLOWLY ORGANIZES TO OUR SOUTH. THE LOW WILL MOVE NE AWAY
FROM THE DETROIT AREA DURING THE DAY ON WEDNESDAY. IFR VSBYS WILL
PREVAIL...WITH THE WORST CONDITIONS AT APN. IMPROVEMENT TO MVFR IS
EXPECTED AT TVC/PLN AROUND MIDDAY...AND TOWARD EVENING AT APN. LAKE
EFFECT SNOW SHOWERS WILL IMPACT TVC WEDNESDAY EVENING AS WINDS BACK
TO THE NNW.
JZ
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR MIZ018-
023-024.
LM...NONE.
LH...SMALL CRAFT ADVISORY UNTIL 5 AM EST THURSDAY FOR LHZ347>349.
SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR LHZ346.
LS...NONE.
&&
$$
