Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 160405
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1205 AM EDT THU APR 16 2015

LATEST UPDATE...
AVIATION

.SYNOPSIS...
ISSUED AT 313 PM EDT WED APR 15 2015

HIGH PRESSURE OVER NEW ENGLAND WILL RESULT IN A SOUTHERLY FLOW
OF MILD AIR HERE IN THE GREAT LAKES REGION TONIGHT AND THURSDAY.
A WEAK WAVE OF LOW PRESSURE WILL TRACK IN FROM THE SOUTH OVERNIGHT
RESULTING IN SOME SHOWERS AND EVEN A THUNDERSTORM INTO THURSDAY.
A DRIER AIRMASS ARRIVES FOR FRIDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 313 PM EDT WED APR 15 2015

THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THE PRECIPITATION
AND THUNDER RISK TONIGHT INTO THURSDAY.

SOME OF THE MODELS...NAM AND GFS...SHOW ELEVATED INSTABILITY
MOVING IN FROM THE SOUTH TONIGHT AND THURSDAY MORNING.
ACCOMPANYING THIS INSTABILITY WILL BE A LOW LEVEL JET...CAUSING
SOME LIFT BELOW THE UNSTABLE LAYER. THUS A RISK EXISTS FOR
THUNDERSTORMS BASED OFF THESE MODELS. WILL KEEP THE MENTION GOING
FOR THURSDAY...BUT WILL NEED TO MONITOR THE POSSIBILITY OF ADDING
IT TO TONIGHTS FORECAST. I DID RAISE POPS TONIGHT AND THU GIVEN
THE BETTER AGREEMENT THAT PRECIPITATION WILL MOVE IN.

POPS WERE DOWNPLAYED FOR THU NIGHT AS THE DEEPER MOISTURE PUSHES
EAST. DRY AIR ADVECTION PERSISTS INTO FRIDAY...SO DRY WEATHER WILL
BE FORECASTED.

ABOVE NORMAL TEMPERATURES EXPECTED THROUGH THE PERIOD WITH A MILD
SOUTHERLY FLOW PERSISTING.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 313 PM EDT WED APR 15 2015

EXTENDED MODELS CONTINUE THE TREND OF BRINGING A COLD FRONT AND
ASSOCIATED PRECIPITATION THROUGH THE REGION SUNDAY AFTERNOON. A
CANADIAN AIRMASS WILL THEN SPREAD SOUTH AND TEMPERATURES WILL FALL
BELOW NORMAL FROM TUESDAY EVENING.  MODEL DATA INDICATES THE
POTENTIAL FOR SNOW TO BE MIXED WITH RAIN ACROSS NORTHERN PORTIONS OF
THE REGION TUESDAY NIGHT INTO WEDNESDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1159 PM EDT WED APR 15 2015

CIGS SHOULD LOWER TO AROUND 5000 FT OVERNIGHT AS SCATTERED RAIN
SHOWERS SPREAD IN FROM THE SOUTH. FURTHER LOWERING OF CIGS
EXPECTED ON THURSDAY WITH MVFR LIKELY AND IFR POSSIBLE.

BEST CHANCE OF IFR THURSDAY IS AT AZO AND BTL AND FELT CONFIDENT
ENOUGH TO BRING IN IFR CIGS AFTER 18Z AT THESE TWO TERMINALS.
HOWEVER CONFIDENCE IN IFR REACHING ANY FARTHER NORTH AND EAST IS
STILL TOO LOW TO PUT IN THE OTHER TAFS.

THE BEST CHANCE OF RAIN TONIGHT LOOKS TO BE FROM AZO NORTH TO
MKG... SPREADING MORE NORTH AND EAST AFTER 12Z. RAIN GRADUALLY
ENDING FROM WEST TO EAST AFTER 18-21Z THURSDAY BUT MVFR TO IFR
CONDITIONS LINGERING INTO THURSDAY NIGHT.

&&

.MARINE...
ISSUED AT 313 PM EDT WED APR 15 2015

IMPACTS TO MARINERS LOOKS LIMITED INTO FRIDAY. WINDS THIS EVENING
WILL BE UP OVER 15 KNOTS AT TIMES. ALSO WITH A SMALL RISK FOR
THUNDER...THAT COULD RESULT IN SOME HAZARDS.


&&

.FIRE WEATHER...
ISSUED AT 313 PM EDT WED APR 15 2015

ELEVATED FIRE DANGER RISK CONTINUES THIS EVENING WITH VERY LOW HUMIDITY
VALUES...GUSTY EAST WINDS AND TEMPERATURES IN THE 60S. LESS OF A
RISK WILL EXIST ON THURSDAY AS MOISTURE MOVES IN FROM THE SOUTH.

&&

.HYDROLOGY...
ISSUED AT 313 PM EDT WED APR 15 2015

UP TO A HALF INCH OF RAIN IS FORECASTED FOR TONIGHT AND THU...MOST
LOCATIONS SHOULD SEE UNDER A QUARTER INCH. THIS SHOULD RESULT IN
MINIMAL IMPACTS TO THE RIVERS.

&&

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

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...MWS
AVIATION...MEADE
FIRE WEATHER...MJS
HYDROLOGY...MJS
MARINE...MJS






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