Area Forecast Discussion
Issued by NWS Grand Rapids, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KGRR 121929
AFDGRR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
329 PM EDT FRI SEP 12 2014

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

.SYNOPSIS...
ISSUED AT 329 PM EDT FRI SEP 12 2014

UNSEASONABLY COOL WEATHER WILL PREVAIL THROUGH THE WEEKEND
THEN A SLOW WARM UP WILL BRING TEMPERATURES CLOSER TO NORMAL.
MEANWHILE AN UPPER AIR SYSTEM MOVING THROUGH THE AREA WILL
SHOWERS TO THE AREA TONIGHT INTO EARLY SATURDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 329 PM EDT FRI SEP 12 2014

LITTLE QUESTION THERE WILL BE SHOWERS ACROSS THE AREA TONIGHT.
THIS IS RELATED TO A STRONG UPPER LEVEL CLOSED LOW WITH A
SIGNIFICANT AMOUNT OF DYNAMIC FORCING MOVING OVER THE AREA. THIS
SYSTEM MOVES THROUGH AN AREA WITH PRECIPITABLE WATER VALUES NEAR
AN INCH WHICH IS MORE THAN ENOUGH TO BRING SHOWERS TO THE AREA.
IT SHOULD BE NOTED THE BEST FORCING IS NORTH OF INTERSTATE 96 SO
THAT IS WHERE THE SOME SIGNIFICANT RAINFALL WILL BE. A LAKE ENHANCED
RAIN-BAND WILL MOSTLY REMAIN OFF SHORE BUT IT MAY COME ON SHORE
TOWARD MORNING BEFORE DRY AIR DISSIPATES IT.

CLEAR SKIES AND LIGHT WINDS SHOULD LEAD TO FROST AND MAYBE
FREEZING TEMPERATURE NEAR ROUTE 10 SATURDAY NIGHT.



.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 329 PM EDT FRI SEP 12 2014

BASED ON MODEL CONSISTENCY...CONFIDENCE IS HIGH THAT WE WILL SEE
A COLD FRONTAL PASSAGE IN THE MONDAY TIME FRAME AIDED BY A STRONG AND
COMPACT UPPER PV ANOMALY SWINGING ACROSS THE AREA. RAINFALL AMOUNTS
ARE EXPECTED TO REMAIN LOW BECAUSE PERSISTENT SURFACE HIGH
PRESSURE CENTERED OVER MUCH OF THE EASTERN U.S. WILL PREVENT AN
INFLUX OF MOISTURE FROM THE GULF OF MEXICO.

TIMING FOR THIS RAIN HAS ALSO BEEN CONSISTENT AMONG THE MODELS FOR
THE LAST SEVERAL RUNS. GENERALLY EXPECT PRECIPITATION TO ENTER THE
NORTHWEST FORECAST AREA AFTER MIDNIGHT SUNDAY NIGHT AND EXIT THE
SOUTHEAST AREA BEFORE MIDNIGHT MONDAY NIGHT.

AFTER WARDS...MEAN UPPER TROUGHING OVER THE EASTERN U.S. WITH RIDGING
UPSTREAM WILL MEAN A DRY PATTERN FOR THE REST OF THE WORK WEEK WITH
COOLER THAN NORMAL NIGHTTIME TEMPERATURES AND A SLOW WARMUP OF
DAYTIME HIGHS TO NEAR SEASONAL VALUES BY FRIDAY.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 146 PM EDT FRI SEP 12 2014

AS MENTIONED IN THE PREVIOUS DISCUSSION...EXPECT MVFR CIGS TO
SPREAD SOUTHEAST THIS AFTERNOON AND TONIGHT WITH AN AREA OF MOSTLY
LIGHT RAIN. ALTHOUGH NOT ADVERTISED AT ALL OF THE TERMINALS...
CEILINGS COULD DROP BELOW THE FUEL ALTERNATE THRESHOLD OF 2000 FT
AGL. IFR CEILINGS ARE ALSO NOT OUT OF THE QUESTION AT MKG AFTER
06Z. OVERALL...THERE ARE FEWER CONCERNS ABOUT RESTRICTIONS TO
VISIBILITY.


&&

.MARINE...
ISSUED AT 329 PM EDT FRI SEP 12 2014

THERE IS ENOUGH CONVECTIVE DEPTH TONIGHT (10,000 T0 15,000 FT ) TO
SUPPORT WATER SPOUTS SO I HAVE THAT IN THE NEAR SHORE. OTHERWISE
I DO NOT SEEM MUCH HAPPENING.

&&

.HYDROLOGY...
ISSUED AT 329 PM EDT FRI SEP 12 2014

RAINFALL SHOULD NOT BE ENOUGH TO RESULT IN ANY SIGNIFICANT HYDRO
ISSUES.

&&

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

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...TJT
AVIATION...TJT
HYDROLOGY...WDM
MARINE...WDM






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.