Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 011925
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
325 PM EDT WED JUL 1 2015

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

.SYNOPSIS...
ISSUED AT 325 PM EDT WED JUL 1 2015

CLOUDS WILL BE MOVING OUT OF THE AREA AND DISSIPATING THROUGH THIS
EVENING. HIGH PRESSURE WILL SETTLE IN ACROSS THE AREA BRINGING
MILD SUMMER WEATHER AND MAINLY DRY CONDITIONS TO THE AREA THROUGH
THE UPCOMING WEEKEND. THERE IS A SLIGHT CHANCE OF A SHOWER OR
STORM ON SATURDAY ALONG U.S.-10 AS A WEAKENING COLD FRONT TRIES TO
MOVE THROUGH.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 325 PM EDT WED JUL 1 2015

THE ONLY ISSUE IN THE SHORT TERM PORTION OF THE FCST IS DEALING
WITH THE CLOUD TRENDS INTO THIS EVENING. OTHERWISE THE FORECAST IS
FAIRLY STRAIGHT-FORWARD THROUGH FRIDAY NIGHT.

WE HAVE SEEN THE CLOUDS BREAK UP A BIT ACROSS MUCH OF THE CWFA
INTO MORE CELLULAR CONVECTIVE CLOUDS VS. THE STRATUS THAT WAS IN
PLACE EARLIER THIS MORNING. IT IS TAKING A LITTLE WHILE LONGER
ACROSS THE NW WHERE THE COOLER AIR OFF OF THE LAKE IS NOT ALLOWING
THE CLOUDS TO MIX OUT AS MUCH AS ACROSS INLAND AREAS.

WE ARE EXPECTING THAT THE WORST CASE SCENARIO IS THAT IT WILL TAKE
UNTIL EARLY THIS EVENING ACROSS THE NW FOR THE CLEARING LINE
ACROSS NRN LAKE MICHIGAN TO MOVE THROUGH THERE.

AFTER THE CLOUDS MOVE OUT THIS EVENING...WE ARE LOOKING AT A
PERIOD OF INCREASINGLY WARMER TEMPERATURES AND DRY CONDITIONS
THROUGH FRI NIGHT. HIGH PRESSURE AT THE SFC WILL REMAIN ALMOST
OVERHEAD BEING DOWNSTREAM OF THE WRN RIDGE AND WITH THE GULF
MOISTURE BEING BOTTLED UP SOUTH OF THE OHIO RIVER VALLEY.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 325 PM EDT WED JUL 1 2015

I AM LOOKING AT THE CHANCE FOR A LATE DAY THUNDERSTORM SATURDAY NEAR
ROUTE 10 WITH A WEAK COLD FRONT. THE MAIN ISSUE THROUGH IS THE
STRONG FRONTAL SYSTEM THAT COMES THROUGH LATE MONDAY OR TUESDAY. I
EXPECT STRONG THUNDERSTORMS WITH THIS FRONT. TIMING OF THIS FRONT IS
AN ISSUE THOUGH.

THE MAIN ISSUE IS A REX BLOCK OVER THE BERING SEA LATE THIS WEEK
THAT FORCES MOST OF THE JET ENERGY OVER THE TOP WITH MEANS IT HAS TO
GO THROUGH THE ARCTIC TO GET HERE. THAT RESULTS IN A STRONGLY
DIGGING NORTHERN STREAM WAVE THAT CREATES A STRONG COLD FRONT FOR
MONDAY OR TUESDAY.  GIVEN THE SIZE OF THESE SYSTEM AND THAT WE ARE
TALKING ABOUT A REX BLOCK...I COULD SEE SLOWING DOWN EVEN MORE THAT
WE ARE NOW SHOWING. IN ANY EVENT THIS WILL BE POLAR AIR MIXING WITH
TROPICAL AIR...WHEN THIS DOES FINALLY HAPPEN I WOULD EXPECT STRONG
STORMS.

A WEAK WAVE TOPS THE UPPER RIDGE AND NUDGES THROUGH SOUTHERN CANADA
SATURDAY. THERE IS JUST ENOUGH INSTABILITY FOR CONVECTION ON THAT
WEAK FRONT NEAR ROUTE 10 SATURDAY AFTERNOON SO I PUT LOW CHANCE POPS
THERE.

THE 500 HEIGHTS...1000/850 THICKNESS TOOLS...1000/925 MB THICKNESS
TOOLS ALL TELL ME HIGHS SHOULD BE IN THE  MID 80S THIS WEEKEND...IF
NOT WARMER. I INCREASED THE HIGHS 3 TO 5 DEGREE SAT THROUGH MONDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 151 PM EDT WED JUL 1 2015

CURRENTLY (1745Z) WE HAVE MVFR CONDITIONS AT MOST OF THE TAF
SITES BUT THE CLOUDS ARE ERODING FROM SOUTH TO NORTH AS THE POLAR
JET SLOWLY LIFTS OUT OF THE AREA. I AM EXPECTING MOST OF THE TAF
SITES TO BECOME VFR (MOSTLY CLEAR) BY 23Z. THE LAN AND JXN ARE
DEEPER INTO THE LOW CLOUDS...THE CLOUDS MAY LINGER LONGER THERE.
EVEN THERE BY 01Z OR SO THEY TOO SHOULD BECOME VFR.

THE GLITCH IN THE FORECAST IS THERE IS SOME SUGGESTION BY THE NAM
AND LESS SO THE RAP MODEL THAT THE LOW CLOUDS WILL SPREAD BACK IN
FROM NORTHEAST TO SOUTHWEST (OFF LAKE HURON) LATER TONIGHT.
I...LIKE THE PREVIOUS FORECAST AM NOT SURE ABOUT THIS SO FOR NOW
I HAVE THE CLOUDS COMING BACK INTO LAN AND BTL LATER TONIGHT.

ALL TAF SITES SHOULD BE MOSTLY CLEAR BY 15Z OR SO THURSDAY AS THE
POLAR JET FINALLY LIFTS OUT OF THE AREA.

&&

.MARINE...
ISSUED AT 325 PM EDT WED JUL 1 2015

WE WILL BE TAKING DOWN THE SMALL CRAFT ADVISORY AND BEACH HAZARDS
STATEMENT WITH THIS FORECAST PACKAGE. WINDS AND WAVES HAVE COME
DOWN ENOUGH TO ALLOW THESE HEADLINES TO EXPIRE ON TIME THIS
AFTERNOON.

IT LOOKS LIKE THAT WE WILL NOT SEE ANY APPRECIABLE WIND AFTER THIS
AFTERNOON...THROUGH MOST OF THE UPCOMING HOLIDAY WEEKEND. THE
GRADIENT WILL REMAIN WEAK ENOUGH TO KEEP WINDS AT OR BELOW 15
KNOTS MOST OF IF NOT ALL OF THE PERIOD.

&&

.HYDROLOGY...
ISSUED AT 1212 PM EDT WED JUL 1 2015

A NARROW SWATH OF ABOUT 1 INCH OF RAIN FELL NEAR AND SOUTH OF
LANSING ON TUESDAY. THIS WATER WILL COLLECT IN THE SYCAMORE CREEK
AND UPPER GRAND RIVER BASIN. THE FLOOD ADVISORIES NEAR HOLT AND
IONIA HAVE BEEN EXTENDED TO ACCOUNT FOR THIS. THE FLOOD ADVISORIES
NEAR COMSTOCK/KALAMAZOO AND NEW RICHMOND CONTINUE... AND RIVER
LEVELS THERE ARE SLOWLY RECEDING. ESSENTIALLY NO PRECIPITATION IS
EXPECTED THROUGH THE WEEKEND.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT UNTIL 4 PM EDT THIS AFTERNOON FOR MIZ037-
     043.

LM...SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR LMZ848-
     849.

&&

$$

SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...WDM
AVIATION...WDM
HYDROLOGY...CAS
MARINE...NJJ



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