Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 261928
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
328 PM EDT TUE APR 26 2016

LATEST UPDATE...
SYNOPSIS/SHORT TERM/LONG TERM/MARINE

.SYNOPSIS...
ISSUED AT 328 PM EDT TUE APR 26 2016

A LARGE CANADIAN HIGH PRESSURE SYSTEM WILL CONTINUE TO PUSH COLD
DRY AIR INTO THE AREA TONIGHT INTO WEDNESDAY EVENING. THE DRY AIR
SHOULD CLEAR THE CLOUDS BEFORE MIDNIGHT. THAT WILL ALLOW FOR SOME
PATCHY FROST OVERNIGHT. A STORM SYSTEM FROM THE SOUTHERN PLAINS
WILL BRING SHOWERS BACK TO THE AREA BY EARLY THURSDAY MORNING. THE
SHOWERS WILL CONTINUE INTO THURSDAY EVENING. THERE IS A SLIGHT
CHANCE OF THUNDERSTORMS THURSDAY AFTERNOON SOUTH OF INTERSTATE 96.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 328 PM EDT TUE APR 26 2016

THERE ARE SEVERAL ISSUES WITH THE FORECAST IN THE SHORT TERM.
FIRST IS DOES THE SKY REALLY CLEAR TONIGHT. ASSUMING IT DOES...
JUST HOW COLD BY MORNING? GIVEN DEW POINTS ARE IN THE 30S AND AIR
TEMPERATURES AT 3 PM STILL MOSTLY IN THE 40S...LOWS BELOW FREEZING
ARE SURELY POSSIBLE NORTH AND EAST OF GRAND RAPIDS TONIGHT. SHOULD
WE ISSUE A FREEZE WARNING FOR TONIGHT? THE NEXT ISSUE IS RAIN AND
POSSIBLE THUNDERSTORMS LATE WEDNESDAY NIGHT INTO THURSDAY...WILL
THAT SYSTEM GET THE MOISTURE THIS FAR NORTH?

FOR THE CLOUD ISSUE ALL OF THE MODELS SHOW THE LOW LEVEL RH
FALLING SHARPLY THIS EVENING AS THE UPPER RIDGE MOVES INTO THE
AREA BETWEEN THE DEPARTING STORM AND ONE HEADING THIS WAY.
TYPICALLY THAT IS ENOUGH TO CLEAR THE SKIES. GIVEN THE CLEARING
LINE IS STILL NORTH OF HTL AT 3 PM... I FIGURE IT MAY TAKE TILL
NEAR MIDNIGHT FOR SKIES TO CLEAR SOUTH OF INTERSTATE 94.

AS FOR THE FREEZE WARNING ISSUE OUR GUIDANCE ON FRUIT TREE BUD
PROGRESS INDICATES WE NEED LOWS IN THE MID 20S OVER CENTRAL AND
NORTHERN ARES TO BE A PROBLEM. I DO THINK MANY AREA NORTH AND EAST
OF GRR WILL HAVE LOWS IN THE UPPER 20S TO LOWER 30S BUT WIDESPREAD
LOWS IN THE MID 20S SEEMS UNLIKELY SO I DO NOT PLAN ON ISSUING A
FREEZE WARNING.

THE SYSTEM COMING AT US FROM THE SOUTHERN PLAINS RUNS INTO
CONFLUENT FLOW ALOFT DUE TO THE LARGE UPPER LOW OVER EASTERN
CANADA. THIS TYPICALLY DOES NOT HELP THE CAUSE FOR GETTING RAIN
INTO THIS AREA. THE MODELS ALL SHOW THE SYSTEM SHEARING OUT AS IT
GETS INTO THE AREA THURSDAY. THE LOW LEVEL JET IS AIMED AT US
WEDNESDAY EVENING BUT FALLS APART BY MORNING (THURSDAY). EVEN SO
WE GET SOME CAPE NEAR AND SOUTH OF INTERSTATE 96 SO I DID PUT A
SLIGHT CHANCE OF THUNDERSTORMS THERE DURING THE DAY THURSDAY. MY
CURRENT THINKING IS THE LAST SYSTEM WAS ALSO SHEARING OUT AS IT
CAME INTO THIS AREA AND WE GOT RAIN THEN...SO I AM THINKING IT
WILL RAIN FROM THIS SYSTEM TOO. SO I HAVE LIKELY POP THURSDAY
DURING THE DAY OVER MOST OF THE CWA.



.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 328 PM EDT TUE APR 26 2016

MODELS ARE IN DECENT AGREEMENT IN TRACKING ONE MID LEVEL SHORTWAVE
EAST OF THE GREAT LAKES REGION FRIDAY.  THERE COULD STILL BE A FEW
REMAINING LIGHT SHOWERS ON THE BACKSIDE OF THIS SYSTEM...BUT OVERALL
THE TREND WILL BE FOR DIMINISHING PRECIPITATION.

MID LEVEL RIDGING THEN MOVES IN FOR FRIDAY NIGHT INTO SATURDAY. THIS
SUPPORT A SHALLOW DRY AND GENERALLY COOL AIRMASS ADVECTING IN FROM
THE NORTHEAST. MEANWHILE...THE GULF OPENS UP FOR THE SECOND HALF OF
THE WEEKEND AS ONE MID LEVEL SHORTWAVE KICKS OUT FROM THE SOUTHWEST
U.S. LOW. OVERRUNNING PRECIPITATION SHOULD DEVELOP HERE IN SOUTHERN
MI AS THIS GULF MOISTURE RIDES UP OVER THE COOL AND DRY AIRMASS THAT
WILL BE IN PLACE.  THUS THE FORECAST WILL FEATURE INCREASING POPS
FROM SATURDAY NIGHT INTO SUNDAY.  IT IS POSSIBLE THAT THIS DRY
AIRMASS COULD KEEP THE MAIN BAND OF RAIN JUST SOUTH OF THE MI BORDER.
MODELS ARE TENDING TO KEEP THE INSTABILITY SOUTH OF MY CWA SO NO
THUNDER WILL BE IN THE FORECAST FOR THE WEEKEND.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 114 PM EDT TUE APR 26 2016

THE IFR CONDITIONS HAVE BEEN SLOW TO BREAK UP THIS MORNING. TRENDS
HAVE DEVELOPED THOUGH...WHICH SUPPORT CONDITIONS GOING TO MVFR
THROUGH MID AFTERNOON. CEILING HEIGHTS HAVE BEEN INCREASING
SLOWLY...PLUS THE SURFACE HUMIDITY HAS BEEN DROPPING OFF. THIS HAS
BEEN REFLECTED IN THE VISIBILITY OBSERVATIONS...WITH NEARLY ALL
SITES OVER 6SM.

VFR CONDITIONS ARE EXPECTED BY 00Z...WITH THE SKIES CLEARING OUT
OVERNIGHT. THIS WILL BE DUE TO A DRIER AIRMASS FILTERING IN FROM
THE NORTHEAST.


&&

.MARINE...
ISSUED AT 328 PM EDT TUE APR 26 2016

WINDS SHOULD DECREASE SOME TONIGHT AND REMAIN LIGHT WEDNESDAY SO
NO HEADLINES ARE NEEDED.

&&

.HYDROLOGY...
ISSUED AT 144 PM EDT TUE APR 26 2016

OVER 2 INCHES OF RAIN FELL IN ISOLATED AREAS LAST NIGHT WITH MOST
LOCATIONS SEEING LESS THAN AN INCH. SOME QUICK RISES ON SMALLER
STREAMS ARE POSSIBLE THROUGH THE NEXT 24 TO 48 HOURS... THOUGH
SIGNIFICANT RISES ON MAIN STEM RIVERS ARE LESS LIKELY GIVEN THE
QUICK HITTING NATURE OF THIS SYSTEM. ADDITIONAL RAINFALL WEDNESDAY
NIGHT INTO THURSDAY WILL ACT TO KEEP SMALLER STREAMS AND RIVERS
ELEVATED THIS WEEK... WITH A SMALLER CHANCE FOR ELEVATED MAIN STEM
RIVERS. FLOODING IS NOT EXPECTED AT THIS TIME.

&&

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

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...MJS
AVIATION...MJS
HYDROLOGY...63
MARINE...WDM



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