000
FXUS63 KGRR 041505
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1005 AM EST WED DEC 4 2013

LATEST UPDATE...
UPDATE

.SYNOPSIS...
ISSUED AT 351 AM EST WED DEC 4 2013

WARM AND WET CONDITIONS WILL MOVE IN ACROSS THE AREA FOR TODAY...OUT
AHEAD OF A STRONGER FRONTAL SYSTEM. TEMPERATURES WILL LIKELY REACH
50 DEGREES AT MANY LOCATIONS WITH RAIN SHOWERS LIKELY. THE STRONG
FRONT WILL MOVE THROUGH TONIGHT. MUCH COLDER AIR WILL POUR IN ACROSS
THE AREA FOR THE REMAINDER OF THE WORK WEEK AND INTO EARLY NEXT
WEEK. HIGHS WILL BE MAINLY IN THE 20S. SOME LAKE EFFECT SNOW SHOWERS
WILL BE POSSIBLE FOR THURSDAY THROUGH THE WEEKEND. WE ARE NOT
EXPECTING SIGNIFICANT ACCUMULATIONS AT THIS TIME.

&&

.UPDATE...
ISSUED AT 1005 AM EST WED DEC 4 2013

I HAVE CANCELLED THE DENSE FOG ADVISORY NEAR THE LAKE MICHIGAN
SHORE AND SOUTH OF INTERSTATE 96 AS VISIBILITIES ARE ALL ABOVE A
MILE. THE FOG IS CURRENTLY DENSE NORTH OF THE WARM FRONT...WHICH
AT 10 AM WAS NEAR I-96. THERE IS AN AREA OF LOWER VISIBILITIES
SOUTH OF INTERSTATE 94 THAT SEEMS TO BE HEADING NORTH BUT WITH THE
WARM FRONT TO NEAR I-96 I WOULD THINK VISIBILITIES SHOULD NOT GO
DOWN BELOW 1/4 MILE AGAIN IN THIS AREA.

THE WARM FRONT IS FORECAST TO ONLY SLOWLY MOVE NORTH INTO MID
AFTERNOON SO WE MAY HAVE TO EXTEND THE FOG ADVISORY OVER OUR
NORTHERN COUNTIES THROUGH THE AFTERNOON.


&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 351 AM EST WED DEC 4 2013

THE MAIN ISSUES IN THE SHORT TERM PORTION OF THE FCST ARE DEALING
WITH THE ADVISORY FOR FREEZING RAIN UP NORTH EARLY THIS MORNING...
AND THEN LAKE EFFECT POTENTIAL BEHIND THE COLD FRONT. WE HAVE NOT
MADE ANY NOTABLE CHANGES TO THE FCST. WE WILL BE DROPPING THE
ADVISORY WITH THIS FCST PACKAGE.

AS MENTIONED ABOVE...WE WILL BE DROPPING THE WINTER WEATHER ADVISORY
WITH THIS PACKAGE. THE WIDESPREAD PCPN HAS MOVED OUT WITH THE SHORT
WAVE RESPONSIBLE FOR PRODUCING IT. TEMPERATURES HAVE ALL GENERALLY
WARMED ABOVE FREEZING...OR WILL DO SO VERY SHORTLY LIKE AT LEOTA IN
CLARE COUNTY.

MOST OF THE AREA SHOULD SEE A BREAK IN THE PCPN /MAINLY RAINFALL
NOW/ THROUGH THIS MORNING. THE SHORT WAVE FROM LAST EVENING IS NOW
EAST OF THE AREA...AND THE NEXT MAIN SURGE OF MOISTURE AHEAD OF THE
NEXT SHORT WAVE IS EXPECTED TO ARRIVE AFTER 18Z. WE DO HAVE SOME CHC
TYPE POPS THIS MORNING UP NORTH TO ACCOUNT FOR THE FEW LIGHT RETURNS
ACROSS CENTRAL AND NRN WI TRYING TO MOVE IN WITH SOME WEAK
WAA/MOISTURE TRANSPORT. WE EXPECT THAT AS UPPER RIDGING TEMPORARILY
BUILDS OVER THE AREA AS THE MAIN UPPER ENERGY GETS READY TO LIFT OUT
OF THE SRN ROCKIES...WE WILL SEE THIS PCPN DRY UP A BIT.

THE BETTER SURGE OF MOISTURE WILL OCCUR AFTER 18Z TODAY AND MOST
LOCATIONS SHOULD SEE ANOTHER ROUND OF SHOWERS. THERMAL PROFILES WILL
ALL EASILY SUPPORT LIQUID PCPN AND STAYING THAT WAY WITH TEMPS
APPROACHING OR EXCEEDING 50 DEGREES F. THE FRONT MOVING THROUGH FROM
ROUGHLY AFTER 03Z AND EXITING BY 09Z WILL SHUT MOST ALL PCPN OFF. WE
WILL SEE PCPN START TO CHANGE OVER TO SNOW ACROSS THE NW PORTION OF
THE CWFA AS THE COLDER AIR BEGINS TO SURGE IN.

WE WILL SEE THE THREAT OF LAKE EFFECT INCREASE SOME FOR LATER THU
AND INTO FRI...HOWEVER WE CONTINUE TO EXPECT THAT THIS WILL NOT BE A
SIGNIFICANT LAKE EFFECT EVENT. INSTABILITY WILL BE MORE THAN
SUFFICIENT WITH H850 TEMPS OF -12 TO -14C COMING IN AND PRODUCING
DELTA T/S IN THE UPPER TEENS. THE FLOW WILL BE ALMOST WRLY THEN
SHIFTING TO WNW WHICH WILL FAVOR THE WRN HALF OF THE CWFA.

THE LIMITATIONS WILL BE STRONG SUBSIDENCE AND A SHALLOW MOISTURE
LAYER. WE WILL BE UNDER THE INFLUENCE OF STRONG SUBSIDENCE AS WE
WILL BE UNDER THE ENTRANCE REGION OF THE STRONG 170 KNOT 300 MB JET.
THIS WILL PRODUCE STRONG RIDGING AT THE SFC OVERHEAD...IN BETWEEN
THE STRONG LOW TO THE NORTH AND THE WINTRY SYSTEM ACROSS THE SE
U.S.. MOISTURE ONLY REACHES UP TO AROUND 3K FT...BUT DOES ENCOMPASS
THE DGZ. CHC TYPE POPS WILL CONTINUE TO BE THE BEST WAY TO GO FOR
THIS EXPECTED SCENARIO.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 351 AM EST WED DEC 4 2013

WINTRY PATTERN FOR SURE EXPECTED THROUGH THE LONG TERM...WITH
COLD...SOME LAKE EFFECT SNOWS AND EVEN SYSTEM RELATED SNOW.

THE LONG TERM BEGINS FRIDAY NIGHT WITH COLD AIR CONTINUING TO SLIDE
INTO THE GREAT LAKES. DELTA T/S WILL BE AROUND 20 C...WHICH IS QUITE
A BIT OF INSTABILITY. THE SITUATION WILL BE LACKING DEEP
MOISTURE...SO EXPECTING LAKE EFFECT SNOW SHOWERS...JUST NOTHING TOO
SIGNIFICANT. ANOTHER LIMITING FACTOR IS LOW LEVEL WINDS WILL BE
ANTICYCLONIC.

SITUATION REMAINS THE SAME SATURDAY AND SATURDAY NIGHT WITH SURFACE
HIGH PRESSURE LIKELY DAMPENING THE THREAT FOR LAKE EFFECT EVEN MORE.
DELTA T/S WILL REMAIN IN THE TEENS C...BUT THE FLOW WILL BECOME WEAK
AND EVEN NEARLY CALM AS WE HEAD INTO SATURDAY NIGHT. LAKE EFFECT MAY
MIGRATE OUT OVER THE LAKE.

SUNDAY THROUGH MONDAY...MODELS INDICATE A LOW PIVOTING NORTH THROUGH
THE GREAT LAKES AS UPPER ENERGY SWINGS OUT OF THE DESERT SOUTHWEST.
SUNDAY MAY END UP MAINLY QUIET...WITH SNOW MOVING THROUGH SUNDAY
NIGHT INTO MONDAY. ACCUMULATING SNOW LOOKS LIKELY AT THIS POINT.
COULD BE LOOKING AT SEVERAL INCHES OF SNOW.

PATTERN THEN SWITCHES BACK INTO A LAKE EFFECT REGIME TUESDAY INTO
WEDNESDAY AS EVEN COLDER AIR POURS INTO THE GREAT LAKES. THE ECMWF
WOULD INDICATE DELTA T/S ON THE ORDER OF 25 C. HIGH INSTABILITY WITH
SHORTWAVES MOVING THROUGH THE FLOW. MOISTURE...INSTABILITY AND LIFT
WOULD ALL BE PRESENT. FLAKE SIZE WOULD BE A LIMITING FACTOR GIVEN
THE COLD TEMPS...A DRY SNOW...BUT WE COULD SEE DECENT ACCUMULATING
LAKE EFFECT SNOW IN THIS TIME FRAME.

SO...WINTRY WEATHER IS THE THEME OF THE LONG TERM. COLD TEMPS WILL
BE IN PLACE OVER THE WEEKEND...WARMING SOME INTO MONDAY WITH THE LOW
SWINGING THROUGH THE AREA AND THEN PLUMMETING INTO MID NEXT WEEK.
HIGHS BELOW NORMAL THE ENTIRE TIME...WITH TUESDAY AND WEDNESDAY
POTENTIALLY SEEING HIGHS REMAINING IN THE TEENS. TUESDAY NIGHT COULD
FEATURE SOME BELOW ZERO LOWS IN THE NORTHEAST CWA.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 724 AM EST WED DEC 4 2013

POOR AVIATION CONDITIONS WILL CONTINUE THROUGH THE DAY AND INTO
TONIGHT AS MOIST SOUTH FLOW STREAMS INTO THE AREA. CEILINGS HAVE
BUMPED UP TO VFR ACROSS THE SOUTH...BUT FEEL THIS IS SHORT LIVED.
BY MIDDAY...CEILINGS WILL BE IFR ACROSS THE ENTIRE AREA ONCE
AGAIN. VISIBILITIES HAVE ALSO RECENTLY COME UP ACROSS THE
SOUTH...BUT SHOULD TREND BACK DOWN ONCE AGAIN AS WE HEAD TOWARD
MIDDAY. FEEL AT LEAST IFR CONDITIONS WILL BE PREVALENT TODAY WITH
PLENTY OF LIFR AS WELL.

SHOWERS WILL BECOME MORE WIDESPREAD AGAIN IN THE MID AFTERNOON
HOURS WITH SCATTERED SHOWERS AT LEAST...MOVING THROUGH THE AREA
IN THE LATE AFTERNOON AND EVENING HOURS. VISIBILITIES WILL LIKELY
REMAIN IFR THROUGH THIS TIME FRAME.

CEILINGS AND VISIBILITIES WILL LIFT LATE TONIGHT...06Z-12Z
FOLLOWING THE PASSAGE OF A COLD FRONT. BY THURSDAY MORNING
CONDITIONS SHOULD BE BACK TO MVFR.


&&

.MARINE...
ISSUED AT 351 AM EST WED DEC 4 2013

THE MAIN PERIOD OF CONCERN LOOKS TO BE FROM LATE THIS EVENING WHEN
THE FRONT MOVES THROUGH...THROUGH THE DAY ON THU. AT THIS TIME...IT
LOOKS LIKE A SOLID SMALL CRAFT ADVISORY EVENT WITH THE COLD AIR
POURING IN. WE COULD SEE WINDS APPROACH ADVISORY CRITERIA THIS
AFTERNOON AND EVENING AHEAD OF THE FRONT...HOWEVER WE ARE NOT
CONFIDENT AT THIS TIME THAT IT WILL INDEED OCCUR.


&&

.HYDROLOGY...
ISSUED AT 351 AM EST WED DEC 4 2013

WE EXPECT NO HYDROLOGY ISSUES IN THE SHORT TERM. BEYOND THE SHORT
TERM...ICE FORMATION COULD CAUSE SOME POTENTIAL ISSUES WITH THE
COLDER WEATHER EXPECTED TO BECOME ESTABLISHED OVER THE AREA.

RAINFALL AMOUNTS WERE GENERALLY UNDER AN INCH WITH THE PCPN
YESTERDAY AND LAST NIGHT. THESE AMOUNTS COMBINED WITH RIVER FLOWS
GENERALLY AROUND AVERAGE SHOULD NOT CAUSE ANY ISSUES. ADDITIONAL
RAINFALL AMOUNTS TODAY AND THIS EVENING SHOULD GENERALLY BE AROUND A
QUARTER OF AN INCH OR SO AND WILL NOT EXACERBATE CONDITIONS MUCH IF
AT ALL.

THE BIGGER CONCERN IS THE ARCTIC AIR MASS COMING IN. WE SHOULD SEE A
FEW DAYS WHERE DAILY AVERAGE TEMPS ARE AROUND 20 DEGREES F. THIS
WILL ALLOW FOR GOOD ICE FORMATION ON THE AREA RIVERS WHICH ALREADY
HAVE SOME ICE ON THEM IN SOME LOCATIONS. THIS WILL HAVE TO BE
MONITORED...ESPECIALLY WHERE ICE JAMS ARE MORE LIKELY TO FORM.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...DENSE FOG ADVISORY UNTIL NOON EST TODAY FOR MIZ038>040-044>046-
     051-052-057>059.

LM...NONE.
&&

$$

UPDATE...WDM
SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...DUKE
AVIATION...DUKE
HYDROLOGY...NJJ
MARINE...NJJ