Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 311937
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
337 PM EDT TUE MAR 31 2015

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

.SYNOPSIS...
ISSUED AT 337 PM EDT TUE MAR 31 2015

MAINLY DRY CONDITIONS ARE EXPECTED TONIGHT THROUGH WEDNESDAY EVENING
AS WEAK HIGH PRESSURE DRIFTS THROUGH THE AREA. AN APPROACHING COLD
FRONT WILL BRING CHANCES FOR SHOWERS AND EVEN A FEW THUNDERSTORMS TO
THE AREA LATE WEDNESDAY NIGHT INTO THURSDAY. THERE WILL BE PERIODS
OF MODERATE RAIN AS SHOWERS AND A FEW THUNDERSTORMS MOVE THROUGH THE
REGION. COOLER AIR WILL FILTER BACK INTO THE REGION FOR LATE IN THE
WEEK AND INTO NEXT WEEKEND AFTER MILD WEATHER WEDNESDAY AND THURSDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 337 PM EDT TUE MAR 31 2015

MAIN ITEM OF NOTE IN THE SHORT TERM IS THE FRONTAL PASSAGE ON
THURSDAY AND THE CHANCES FOR SHOWERS AND STORMS ASSOCIATED WITH
STRETCHING FROM WEDNESDAY NIGHT INTO THURSDAY EVENING. SHOWERS AND
EMBEDDED THUNDERSTORMS WILL PRESS INTO THE AREA FROM THE WEST AFTER
MIDNIGHT ON A SURGE OF 850MB MOISTURE TRANSPORT. A STRONG LLJ
LOCATED UPSTREAM WEDNESDAY EVENING WILL BEND INTO THE AREA OVERNIGHT
A LOSE A BIT OF PUNCH/SPEED. INSTABILITY IS NOT ALL THAT IMPRESSIVE
WITH MU CAPE VALUES ON THE ORDER OR 500 J/KG. ENOUGH INSTABILITY
THOUGH TO KEEP STORMS IN THE FORECAST...NOTHING SEVERE.

ON THURSDAY THE SHOWERS AND STORMS WILL LIKELY UNDERGO A DIURNAL
FADE IN THE MORNING...TRYING TO REINTENSIFY DURING THE AFTERNOON.
SHOWERS AND A FEW STORMS WILL BECOME PREVALENT ONCE AGAIN THURSDAY
AFTERNOON...ESPECIALLY ACROSS SOUTHERN LOWER MICHIGAN. FEEL SEVERE
THREAT IS MINIMAL ONCE AGAIN GIVEN WEAK INSTABILITY. RAINFALL
AMOUNTS SHOULD BE ON THE ORDER OF 0.25 TO 0.75 THROUGH THE COURSE OF
THE EVENT...SO NOTHING TOO HEAVY.

OTHERWISE...A FEW FLURRIES WILL BE POSSIBLE LATER THIS EVENING
ACROSS CENTRAL LOWER MICHIGAN ASSOCIATED WITH A WEAK SHORTWAVE
MOVING THROUGH THE NORTHERN LAKES.

.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 337 PM EDT TUE MAR 31 2015

THE LONG TERM PORTION OF THE FCST WILL FEATURE A RETURN TO COOLER
CONDITIONS IN THE BEGINNING...WITH A TREND TOWARD UNSETTLED
CONDITIONS FROM LATE IN THE WEEKEND THROUGH THE FIRST PORTION OF
NEXT WEEK.

WE HAVE ADDED THE THREAT FOR PCPN BACK INTO THE FCST FOR THE FRI AND
FRI NIGHT TIME FRAME. THERE IS GOOD AGREEMENT AMONGST THE MODELS
THAT THE UPPER WAVE THAT HAS BEEN PROGGED TO LIFT NE FROM THE FOUR
CORNERS REGION...WILL BRING THE SFC WAVE ALONG THE FRONT CLOSE
ENOUGH TO THE AREA TO BRING PCPN CHCS TO THE AREA. ENOUGH WARM
ENOUGH AIR WILL REMAIN IN PLACE EARLY ON FRI TO KEEP PCPN RAIN. WE
DO EXPECT A CHANGE OVER TO SOME SNOW BY FRI EVENING AS COLD AIR IS
DRAWN SOUTH FROM CANADA BEHIND THE WAVE.

THERE IS A SMALL CHC OF SOME RAIN OR SNOW SHOWERS LATER ON SAT AFTER
A BRIEF BREAK LATE FRI NIGHT AND SAT MORNING. THIS COMES WITH A COLD
FRONT THAT WILL BRUSH THE AREA. THE BETTER CHC OF PCPN WILL COME
BACK ON SUN AS THE FRONT RETURNS NORTH AND MOISTURE RETURNS.

THERE IS QUITE A BIT OF UNCERTAINTY WITH THE DETAILS FROM MON
THROUGH TUE FOR THE AREA. THE FRONT THAT RETURNS NORTH ON SUN WILL
BECOME STALLED OUT AS IT BECOMES PARALLEL WITH A ZONAL UPPER FLOW
OVER THE REGION. THIS WILL BE THE FOCUS FOR OCCASIONAL WAVES OF PCPN
ALONG IT...SO WE HAVE CHCS OF PCPN IN FOR MON AND TUE. SOME OF THE
PCPN INITIALLY COULD END UP BEING A WINTRY MIX AT TIMES WITH A SFC
HIGH TO OUR NORTH FUNNELING IN COOLER AND DRIER AIR.

PCPN WILL EVENTUALLY BECOME ALL RAIN WITH WARMER AIR COMING IN LATE
IN THE PERIOD AND BEYOND AS A WRN TROUGH DIGS AND THE FLOW BECOMES
MORE SWRLY OVER THE AREA.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 138 PM EDT TUE MAR 31 2015

THE ONLY REAL IMPACT TO AVIATION INTERESTS WILL BE RIGHT AT THE
BEGINNING OF THE FCST PERIOD. LOW CLOUDS HANGING AROUND BEHIND THE
SYSTEM ARE IN THE PROCESS OF LIFTING AND MIXING OUT FROM NORTH TO
SOUTH THIS AFTERNOON. WE EXPECT THE TERMINALS TO GO VFR BY 21Z.
THE ONLY EXCEPTION TO THIS MIGHT BE KMKG WHERE SOME STRATUS OVER
LAKE MICHIGAN COULD COME ONSHORE. IT SHOULD BURN OFF QUICKLY WITH
THE INLAND AREAS STARTING TO HEAT UP AND DRY OUT.

OTHERWISE...SKIES SHOULD GENERALLY BECOME MOSTLY CLEAR AND REMAIN
THAT WAY THROUGH 18Z TOMORROW. A SYSTEM TO OUR NORTH MIGHT BRING
SOME SCT CLOUDS AROUND 5K FEET THIS EVENING TO KMKG...BUT THAT
WOULD BE ABOUT IT.

&&

.MARINE...
ISSUED AT 337 PM EDT TUE MAR 31 2015

WILL HOLD OFF ON A SMALL CRAFT ADVISORY AT THIS POINT...BUT IT LOOKS
LIKE ONE MAY BE NEEDED WEDNESDAY NIGHT. IT IS INTO THE 3RD
PERIOD...AND THERE IS SOME QUESTION AS TO HOW MUCH WIND WILL MIX
DOWN IN A WARM AIR ADVECTION SETUP. THINKING 3 TO 5 FOOT WAVES AT
THIS POINT...WITH SOUTH WINDS TO 30 KNOTS. UNTIL THAT TIME...FAIRLY
QUIET CONDITIONS GIVEN LIGHT WINDS.

EXPECTING MARINE FOG TO CONTINUE TO MIX OUT AS WE HEAD THROUGH THE
REMAINDER OF THE EVENING.

&&

.HYDROLOGY...
ISSUED AT 1120 AM EDT TUE MAR 31 2015

RIVERS CONTINUE TO REMAIN WELL BELOW ADVISORY LEVELS WITH ONLY SMALL
AND MOMENTARY RESPONSES NOTED FROM RECENT PRECIPITATION. NORTHERN
SECTIONS OF THE FORECAST AREA WILL SEE SLOWER RESPONSES DUE TO
SNOW MELT WITH LAST NIGHTS SNOWFALL.

WE WILL SEE A RATHER ACTIVE PATTERN SET UP THROUGH THE NEXT 7
DAYS. MUCH OF THIS COMES IN TWO WAVES...ONE THURSDAY THEN THE
SECOND VERY LATE IN THE WEEKEND AND INTO THE NEXT WORK WEEK. GENERAL
AMOUNTS ON TOTAL PRECIPITATION THROUGH THE PERIOD ARE AROUND ONE
INCH OR SO. THIS IS FAIRLY EVENLY DIVIDED BETWEEN THE TWO WAVES
WHICH SHOULD BE FAVORABLE FOR RESPONSE TIMES. NO FLOODING IS
EXPECTED AT THIS TIME. HOWEVER...THE HEAVIER RAIN THAT IS
ANTICIPATED TO OUR SOUTH THROUGH THE OHIO VALLEY SHOULD BE WATCHED
IN THE EVENT THAT ANY ADJUSTMENTS ARE NEEDED IN PRECIPITATION
AMOUNTS.

&&

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

$$

SYNOPSIS...DUKE
SHORT TERM...DUKE
LONG TERM...NJJ
AVIATION...NJJ
HYDROLOGY...JAM
MARINE...DUKE









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