Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 160001
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
801 PM EDT WED APR 15 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 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 800 PM EDT WED APR 15 2015

VFR CONDITIONS ARE LIKELY FOR THE MAJORITY OF THE NIGHT DUE TO THE
VERY DRY AIR MASS THAT IS CURRENTLY IN PLACE. EVEN AS SCATTERED
SHOWERS DEVELOP OVERHEAD OR MOVE IN AFTER MIDNIGHT... THESE
SHOULD BE FALLING FROM CLOUD BASES AT OR ABOVE 5000 FT.

GUIDANCE INDICATES MVFR OR LOWER CIGS DEVELOPING ON THURSDAY AS
THE LOW LEVELS CONTINUE TO MOISTEN. AM SOMEWHAT SKEPTICAL OF THIS
HOWEVER GIVEN THAT SFC RELATIVE HUMIDITIES ARE CURRENTLY LESS
THAN 25 PCT.

WILL MAINTAIN THE IDEA OF MVFR DEVELOPING AT MOST OF THE TERMINALS
THURSDAY MORNING AS COVERAGE OF RAIN INCREASES... BUT CONFIDENCE
FOR ANY IFR IS TOO LOW AT THIS TIME TO PUT IN THE TAFS. CONFIDENCE
ALSO TOO LOW TO INCLUDE ANY THUNDERSTORMS IN THE TAFS BUT THERE IS
A VERY SLIGHT RISK OF THAT TOO.

WHILE SFC WINDS WILL BE AROUND 10-15 KTS TONIGHT... THE WINDS JUST
ABOVE THE SFC AT 1000 FT WILL BE 30-40 KTS THROUGH ABOUT 10Z.
LIGHTER WINDS ARE EXPECTED FOR THURSDAY... PARTICULARLY IN THE
AFTERNOON.


&&

.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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