Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 271744
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
144 PM EDT MON OCT 27 2014

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 330 AM EDT MON OCT 27 2014

AFTER A FEW SHOWERS AND THUNDERSTORMS THIS MORNING NORTH OF
INTERSTATE 96... SOUTHERLY WINDS WILL SEND UNSEASONABLY WARM AIR
INTO SOUTHERN MICHIGAN THIS AFTERNOON WITH HIGHS REACHING INTO THE
70S ACROSS MUCH OF THE AREA.

A COLD FRONT WILL BRING ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS
TONIGHT INTO EARLY TUESDAY FOLLOWED BY COOLER WEATHER FOR THE REST
OF THE WEEK. VERY CHILLY AIR ARRIVES ON HALLOWEEN DAY AND WE MAY
SEE SOME OF THE FIRST SNOWFLAKES OF THE SEASON.

&&

.UPDATE...
ISSUED AT 1047 AM EDT MON OCT 27 2014

NO MAJOR CHANGES TO THE FCST THIS MORNING. WE HAVE FRESHENED UP
THE FCST TO CHIP AWAY AT THE RAIN CHCS THIS MORNING AS THE
ELEVATED CONVECTION CONTINUES TO SHIFT NORTH OF THE AREA. WE
SHOULD SEE A LULL IN THE PCPN AS CONVECTION MOVES ENTIRELY OUT OF
THE AREA THIS MORNING AS THE NOSE OF THE LLJ/MOISTURE TRANSPORT
SHIFTS OUT OF THE AREA TO THE NE.

RAIN CHCS WILL THEN INCREASE ONCE AGAIN OVERNIGHT TONIGHT AS
ANOTHER SURGE OF WARMTH AND MOISTURE AHEAD OF THE COLD FRONT MOVES
ACROSS THE AREA.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 330 AM EDT MON OCT 27 2014

NW-SE BANDS OF SHOWERS AND THUNDERSTORMS HAVE BEEN DEVELOPING EARLY
THIS MORNING ON THE LEADING EDGE OF THE ELEVATED WARM FRONT IN AREA
OF MU CAPES AROUND 1000 J/KG. SHORT TERM GUIDANCE SUGGESTS THIS
ACTIVITY MAY BECOME A BIT MORE NUMEROUS THROUGH 12Z MAINLY NORTH OF
I-96 BEFORE EXITING OFF TO THE NORTHEAST BETWEEN 15Z AND 18Z.

THE SFC WARM FRONT ARRIVES FROM THE SOUTH AFTER 18Z AND BRINGS WITH
IT SFC DEW PTS OF 55 TO 60. THIS COMBINED WITH TEMPERATURES IN THE
70S WILL MAKE IT FEEL RATHER SUMMER LIKE. IT IS QUESTIONABLE HOW FAR
NORTH THE WARM FRONT MAKES IT SO TEMPERATURES ARE TRICKY ALONG THE
U.S. 10 CORRIDOR AND IT MAY STRUGGLE TO REACH 60 AT REED CITY AND
CLARE.

THE SOUTHEAST LOW LEVEL FLOW SHOULD ALLOW LAKESHORE AREAS TO GET
JUST AS WARM OR WARMER THAN INLAND LOCALES... AND THE RECORD HIGH OF
74 FOR THE DATE AT MUSKEGON COULD BE IN JEOPARDY. THE RECORDS OF
78/80 AT GRR/LAN SHOULD STAND.

DECENT COVERAGE OF SHOWERS IS ANTICIPATED WITH THE COLD FRONTAL
PASSAGE LATE TONIGHT AND EARLY TUESDAY. HOWEVER TSTM COVERAGE SHOULD
BE ISOLATED WITH MU CAPES MOSTLY BELOW 1000 J/KG.

WINDY/GUSTY CONDITIONS ARE LIKELY ON TUESDAY AS THE DRY SLOT SWEEPS
IN AND CYCLONIC FLOW PROMOTES DEEP MIXING. CLOUDS AND ISOLATED
SHOWERS SHOULD WRAP BACK IN LATE TUESDAY NIGHT AND WEDNESDAY AS
SUB ZERO H8 AIR ARRIVES.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 330 AM EDT MON OCT 27 2014

THE MEDIUM RANGE MODELS CONTINUE TO SHOW A STRONG SHOT OF COLD AIR
MOVING SOUTH ACROSS THE GREAT LAKES ON HALLOWEEN. LEADING UP TO
FRIDAY HIGH PRESSURE WILL SETTLE OVER THE REGION AND GENERATE FAIR
WEATHER WEDNESDAY NIGHT AND THURSDAY. A CLIPPER MOVING SE FROM THE
PRAIRIE PROVINCES WILL DRAW DOWN COLDER AIR FROM NORTHERN CANADA AS
IT MOVES SOUTHEAST FROM LAKE SUPERIOR TO LAKE HURON. THE ECMWF IS
THE COLDER OF THE SOLUTIONS AND INDICATES H8 TEMPS NEAR -10C WHILE
THE GFS IS SHOWS -7C. IN EITHER CASE FORECAST SOUNDINGS SHOW THAT
THIS AIR HAS A GOOD CHANCE AT BEING COLD ENOUGH FOR SOME WET SNOW TO
MIX IN WITH SCATTERED RAIN SHOWERS THURSDAY NIGHT AND FRIDAY. THE
PCPN THAT DOES OCCUR WILL COME MOSTLY AS A RESULT OF THE LOW ITSELF
RATHER THAN LAKE EFFECT PCPN DUE TO NORTHERLY BOUNDARY LAYER WINDS.
HIGHS ON FRIDAY WILL BE MUCH BELOW NORMAL...UPPER 30S TO MID 40S. A
WARMING TREND WILL DEVELOP OVER THE WEEKEND WITH 50S EXPECTED BY THE
FOLLOWING MONDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 140 PM EDT MON OCT 27 2014

I EXPECT NEARLY CLEAR SKIES MOST OF THE AFTERNOON WITH SOUTH WINDS
GUSTING TO 25 KNOTS AT TIMES. THE FRONTAL CLOUD BAND MOVES IN LATE
IN THE EVENING. AN AREA OF SHOWERS AND ISOLATED THUNDERSTORMS WILL
CROSS THE TAF SITES BETWEEN 06Z AND 12Z NEAR MKG TO 10Z TO 16Z BY
JXN. COULD BE BRIEF IFR CONDITIONS WITH MODERATE RAIN SHOWERS AND
LOW CIGS JUST AHEAD OF THE FRONT. ONCE THE FRONT COMES THROUGH THE
DRY SLOT SHOULD CLEAR OR NEARLY CLEAR THE SKY BUT IT WILL BECOME
BREEZE.

&&

.MARINE...
ISSUED AT 1047 AM EDT MON OCT 27 2014

WE HAVE HOISTED A SMALL CRAFT ADVISORY VALID FROM THE CURRENT TIME
THROUGH WED AFTERNOON. WINDS ARE FAIRLY BREEZY THIS MORNING OUT OF
THE SOUTHEAST AHEAD OF THE INCOMING FRONT. SOME WIND GUSTS ALONG
THE COAST HAVE BEEN UP AROUND 25 KNOTS ALREADY. WE EXPECT THAT
WITH AN OFFSHORE WIND AND DECENT MIXING OVER LAND...STRONGER WINDS
ALOFT WILL MIX DOWN AND AFFECT THE NEARSHORE WATERS. AS MIXING
OVER THE LAND DIMINISHES TONIGHT...WINDS WILL BECOME SW IN THE
WARM SECTOR WITH A STRONG GRADIENT REMAINING IN PLACE. COLD AIR
ADVECTION THEN ON TUE THROUGH WED WILL KEEP WINDS AND WAVES UP
DURING THAT PERIOD.


&&

.HYDROLOGY...
ISSUED AT 1149 AM EDT MON OCT 27 2014

THE OVERALL TREND THIS WEEKEND HAS BEEN TO GRADUALLY STEP BACK ON
PRECIP TOTALS. IT SEEMS THAT THE CHANCES FOR ANY HIGHER TOTALS
IS LOW AND WOULD BE THE OUTLIER. I SUPPOSE SOME LOCALIZED AREAS
WOULD EXCEED HALF AN INCH OR SO IF AFFECTED BY THUNDERSTORMS
TONIGHT...JUST AS THEY HAD IN NORTHERN SECTIONS OF THE FORECAST
AREA THIS MORNING. THIS SHOULD NOT LEAD TO ANY FLOODING ISSUES.
RIVERS ARE ALREADY RUNNING WELL WITHIN THEIR BANKS. WITH RECENT
DRY WEATHER ANY INCOMING PRECIP WOULD JUST BE BENEFICIAL AT THIS
POINT.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM EDT WEDNESDAY FOR LMZ844>849.

&&

$$

UPDATE...NJJ
SYNOPSIS...MEADE
SHORT TERM...MEADE
LONG TERM...93
AVIATION...WDM
HYDROLOGY...JAM
MARINE...NJJ






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