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000
FXUS63 KGRR 161647
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1245 PM EDT THU MAY 16 2013

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 345 AM EDT THU MAY 16 2013

THE WEATHER SHOULD REMAIN RATHER QUIET THROUGH THE UPCOMING WEEKEND.
A FRONTAL SYSTEM WILL REMAIN MAINLY SOUTH OF THE AREA THROUGH THE
PERIOD. ANOTHER FRONTAL SYSTEM WILL TAKE SHAPE THROUGH THE PERIOD
WEST OF THE AREA...AND SHOULD REMAIN THERE THROUGH THE WEEKEND.
LOWER MICHIGAN BEING IN BETWEEN THE SYSTEMS SHOULD SEE SOME SUNSHINE
AND MILD TEMPS.

RAIN CHANCES WILL INCREASE EARLY NEXT WEEK AS A SYSTEM APPROACHES
THE AREA FROM THE WEST/SOUTHWEST.

&&

.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 345 AM EDT THU MAY 16 2013

THE MAIN FOCUS OF THE SHORT TERM WILL BE WHAT RAIN CHANCES THE AREA
WILL HAVE IF ANY.

THE FRONTAL SYSTEM THAT MOVED THROUGH EARLY ON WED HAS SETTLED WELL
SOUTH OF THE AREA THIS MORNING...AND IS SOMEWHAT ACTIVE WITH
CONVECTION DOWN ACROSS IL/IN/OH. OUR MAIN WX FEATURE AT LEAST FOR
THE NEXT COUPLE OF DAYS WILL BE HIGH PRESSURE CURRENTLY ACROSS
CENTRAL CANADA THAT IS SLOWLY BUILDING TO THE EAST. WE WILL BE ON
THE SRN FLANK OF THIS RIDGE.

THE WEAK PRESSURE PATTERN ACROSS THE REGION THIS AFTERNOON WILL
ALLOW THE GREAT LAKES TO HAVE MESOSCALE EFFECTS DOMINATE THE
WEATHER. WE WILL SEE RIDGING ENHANCED OVER THE COOLER LAKES...AND A
WEAK TROUGH INLAND THAT WILL RESULT IN BETWEEN LAKES HURON AND
MICHIGAN. THE GFS IS TRYING TO PRINT OUT SOME LIGHT PCPN THIS
AFTERNOON ACROSS THE SE COUNTIES. FCST SOUNDINGS FROM THE VARIOUS
MODELS INDICATE A FAIR AMOUNT OF DRY AIR BELOW 700 MB AND WARM MID
LEVELS. WE BELIEVE THESE FACTORS AND OVERFORECAST MOISTURE JUSTIFY A
DRY FCST.

LATER ON FRI AND INTO EARLY SAT...THE MODELS ARE TRYING TO LIFT THE
NEARLY STATIONARY BOUNDARY SOUTH OF THE AREA BACK NORTH AS A WARM
FRONT. THIS IS IN RESPONSE TO A BUILDING UPPER RIDGE TO OUR WEST AS
A STRONG TROUGH/LOW MOVES OVER THE CA COAST. WHAT WE EXPECT TO
HAPPEN IS THAT THERE WILL BE SOMEWHAT OF A SPLIT IN THE UPPER JET AS
THE RIDGE BUILDS TO OUR WEST AND THE TROUGH MOVING ACROSS THE SRN
STATES CONTINUES SLOWLY EAST AND IS NOT EXPECTED TO BE PHASED WITH
THE NRN BRANCH.

THIS SHOULD HELP PCPN STAY SOUTH OF THE AREA WITH THE SRN LOW...AND
PCPN JUST TO OUR WEST SHOULD MIGRATE CLOSER TO THE STRENGTHENING SFC
LOW AND BETTER MOISTURE TRANSPORT WITH THE ASSOCIATED LOW LEVEL JET.
WE EXPECT PCPN TO GENERALLY EVAPORATE/DISSIPATE WITH THIS SPLIT
OCCURRING. WE WILL SEE SOME MOISTURE ADVECTION TAKE PLACE...BUT IT
WILL TAKE A WHILE FOR THE FLOW TO BECOME MORE SRLY AND ADVECT THE
MOISTURE INTO THE AREA IN THE LOW/MID LEVELS. IT IS STILL POSSIBLE
FOR THE AREA TO SEE A LOW CHC OF SOME RAIN FRI NIGHT AND SAT. THE
ODDS ARE THOUGH NO ONE WILL SEE THE RAIN WITH THIS SETUP...SO WE
HAVE A DRY FCST FOR NOW.

TEMPS SHOULD STAY FAIRLY STABLE THROUGH THE PERIOD. WE WILL NOT SEE
MUCH TEMPERATURE ADVECTION THROUGH THE PERIOD. H850 TEMPS AROUND
9-12C WILL SUPPORT TEMPS WILL INTO THE 70S AND APPROACHING 80 DOWN
SOUTH.

.LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 345 AM EDT THU MAY 16 2013

UPPER PATTERN IN THE LONG TERM STARTS WITH AN UPPER RIDGE IN PLACE
ACROSS THE GREAT LAKES...AND AN UPPER LOW SETTLING INTO THE NORTHERN
PLAINS. INTO EARLY NEXT WEEK...THE UPPER LOW GRADUALLY NUDGES EAST
BECOMING CENTERED OVER MINNESOTA BY MIDDAY TUESDAY. RIGHT ABOUT THAT
TIME...SOLUTIONS DIVERGE BETWEEN THE ECMWF AND THE GFS. THE ECMWF
ALLOWS THE UPPER LOW TO INTERACT WITH A TROUGH OVER EASTERN CANADA
PULLING THE LOW INTO THE GREAT LAKES AND BRINGING IN COOLER AIR
TOWARD THE END OF THE WORK WEEK. THE GFS KEEPS THE NORTHERN PLAINS
UPPER LOW AND EASTERN CANADA TROUGH SEPARATE AND HENCE KEEPING OUR
AREA IN SOUTHWEST FLOW THROUGH MID WEEK. CONFIDENCE IS LOW IN HOW
THIS WILL PLAY OUT...BUT HAVE TRIED TO USE SOMEWHAT OF A MEAN
BETWEEN THE TWO.

EXPECT DRY WEATHER SATURDAY NIGHT AND SUNDAY AS THE LOW LEVEL FLOW
WILL REMAIN SOUTHEAST. UPPER RIDGING SHOULD BE DIRECTLY OVERHEAD AS
WELL.

HAVE A 20 PCT CHC FOR SHOWERS/STORMS IN THE WEST SUNDAY NIGHT FOR
ANY CONVECTION THAT MAY TRY TO ADVECT IN FROM THE WEST. NOT REAL
CONFIDENT THAT WE WILL SEE ANY PRECIP THROUGH 12Z MONDAY THOUGH AS
THE BEST MOISTURE ADVECTION REMAINS WEST OF LAKE MI.

30-50 PCT CHANCES FOR SHOWERS/STORMS ARE IN THE FORECAST FROM MONDAY
THROUGH WEDNESDAY AS BETTER MOISTURE ADVECTION BECOMES AIMED AT THE
GREAT LAKES. SOUTHERLY FLOW SHOULD TAP SOME GULF MOISTURE DURING
THIS TIME FRAME. ENVISION A DIURNAL FLARE TO THE PRECIP DURING THIS
TIME FRAME. MID LEVEL COOLING WILL BE OCCURRING WITH THE UPPER LOW
NUDGING OUR WAY AT THE SAME TIME LOW LEVEL THETA-E ADVECTION WILL BE
TAKING PLACE.

TEMPERATURES THROUGH THE PERIOD WILL BE ABOVE NORMAL WITH THE
POTENTIAL FOR 80S ALMOST EACH DAY. THE QUESTION MARK WILL BE HOW
MUCH CLOUD COVER AND PRECIPITATION WILL BE AROUND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY)
ISSUED AT 1245 PM EDT THU MAY 16 2013

VFR CONDITIONS WILL CONTINUE AT ALL THE TERMINALS THROUGH 18Z
FRIDAY. NW WINDS OF AROUND 10 KTS THIS AFTN WILL SUBSIDE TO BELOW 10
KTS TONIGHT THROUGH 18Z FRIDAY AND GRADUALLY VEER TO THE NORTH THEN
NE OVERNIGHT.

&&

.MARINE...
ISSUED AT 345 AM EDT THU MAY 16 2013

NO MARINE HEADLINES ARE ANTICIPATED OVER THE NEXT COUPLE OF
DAYS...AND EVEN LIKELY THROUGH MOST OF THE WEEKEND. WINDS SHOULD
REMAIN AT OR BELOW 15 KNOTS THROUGH FRI. SOME INCREASE IN WIND LOOKS
TO OCCUR THROUGH THE DAY ON SAT...HOWEVER WIND SHOULD REMAIN BELOW
20 KNOTS. WE COULD BE LOOKING AT SOME POSSIBLE HEADLINES LATE SUN AS
THE GRADIENT INCREASES ENOUGH.


&&

.FIRE WEATHER...
ISSUED AT 345 AM EDT THU MAY 16 2013

FIRE WEATHER CONDITIONS REMAIN ELEVATED ACROSS THE AREA WITH LITTLE
RAIN HAVING OCCURRED OVER THE LAST FEW DAYS. METEOROLOGICAL
CONDITIONS WILL BE CONDUCIVE TO KEEP FIRE DANGER ELEVATED NOW LIKELY
INTO THE WEEKEND. RED FLAG CONDITIONS ARE NOT EXPECTED TO BE
MET...MAINLY DUE TO THE LIMITED WINDS EXPECTED. MIN RH/S SHOULD DROP
INTO THE 20S DURING THE DAY AND TEMPS IN THE 70S.

&&

.HYDROLOGY...
ISSUED AT 345 AM EDT THU MAY 16 2013

HYDROLOGY CONCERNS WILL REMAIN AROUND ZERO NOW THROUGH THE WEEKEND.
MODELS CONTINUE TO TREND DRIER AND DRIER THROUGH SUNDAY WITH LITTLE
TO NO RAIN EXPECTED. RIVER AND STREAM LEVELS ARE RUNNING AROUND
AROUND AVERAGE.

IT STILL APPEARS THAT MOST OF THE AREA SHOULD SEE A SOMEWHAT SOAKING
RAIN NEXT WEEK WITH OVER HALF AN INCH OF RAIN LIKELY. AMOUNTS
EXPECTED TO REMAIN BELOW AN INCH FOR THE MOST PART SHOULD HAVE ONLY
LIMITED EFFECTS ON THE RIVERS AND STREAMS DUE TO THE SOILS STARTING
TO DRY OUT SOME AND SOAKING UP ANY RAINFALL THAT OCCURS.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&

$$

SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...DUKE
AVIATION...LAURENS
FIRE WEATHER...NJJ
HYDROLOGY...NJJ
MARINE...NJJ