Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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777
FXUS63 KDTX 221004
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
604 AM EDT FRI MAY 22 2015


.AVIATION...

HIGH PRESSURE BUILDING IN AT THE SURFACE AND ASSOCIATED DRY AIR
ADVECTION WILL QUICKLY CLEAR SKIES OUT THIS MORNING. FULL SUNSHINE
AND LIGHT WINDS WILL THEN CARRY THROUGH FOR THE REMAINDER OF TODAY.
A NOTABLE ITEM IS A WINDSHIFT TO THE EAST WILL OCCUR AS A LAKE
BREEZE BOUNDARY PUSHES INLAND AWAY FROM LAKE ERIE/ST CLAIR AND THE
RIVERS AFTER 23Z TODAY.

//DTW THRESHOLD PROBABILITIES...

* NONE.

&&

.PREV DISCUSSION...ISSUED 401 AM EDT FRI MAY 22 2015

SHORT TERM...TODAY AND TONIGHT

A WEAK SYNOPTIC COLD FRONT WILL CONTINUE TO SLIP SOUTHWARD ACROSS
SOUTHEASTERN MICHGIAN THROUGH 12Z. THE BACKDOOR SURFACE FRONT IS
SUPPORTED ALOFT BY A COMBINATION OF PHASING SHORTWAVE ENERGY AND A
CONFIGURATION OF UPPER LEVEL SPEED MAXIMA FAVORABLE TO SYNOPTIC
SCALE ASCENT. REGIONAL MOSAIC RADAR IMAGERY THIS MORNING HAS BEEN
SHOWING A SMATTERING OF ELEVATED RAIN SHOWERS IN ADVANCE OF THIS
SURFACE FRONT WITHIN A RIBBON OF HIGHER MIDLEVEL THETE E CONTENT. A
NARRATIVE OF MORE BARK THAN BITE WITH IT BEING VERY DIFFICULT TO
FIND SURFACE OBSERVATION SITES REPORTING -RN. THEREFORE...THE
ACTIVITY THUS FAR IS BETTER CHARACTERIZED AS VIRGA/SPRINKLES.

NWP DATA SUGGESTS THE WEAK SYSTEM RELATIVE ISENTROPIC ASCENT THAT
EXISTED BETWEEN 00-06Z WILL NOT ONLY WEAKEN...BUT WILL QUICKLY FLASH
SOUTHWARD TO SOUTH OF THE STATE LINE BY 9Z. IN FACT...FORCING WILL
RAPIDLY TRANSITION TO STOUT ISENTROPIC DOWNGLIDE BY 12Z. WHILE ONE
LAST BATCH OF REMNANT DEEPER CONVECTION NOW OVER FAR SW MICHIGAN
WILL SLIDE EASTWARD ALONG THE SOUTHERN MICHIGAN BORDER...THE
INHERITED GRIDS OF ENDING PRECIPATION CHANCE AROUND 9-10Z REMAINS
VALID.

THERE IS HIGH CONFIDENCE THAT ONCE THE MIDCLOUD ALTOCUMULUS SAGS
SOUTHWARD...CLEAR SKIES WILL BE PLACE FOR THE DURATION OF TODAY.
DESPITE FULL INSOLATION...A FRESH CANADIAN AIRMASS WILL LEAD TO
COOLER TEMPERATURES...WITH READINGS RANGING FROM THE LOWER 50S
ALONG THE LAKE HURON SHORELINE TO THE MID 60S ACROSS THE SOUTHERN
2 TIERS.

A STRONG LAKE AGGREGATE STRUCTURE IN THE FORECASTED MSLP THIS
AFTERNOON IN ADDITION TO DETERMINITIC SOLUTIONS POINT TO A
RELATIVELY ROBUST LAKE BREEZE RELEASE VERY LATE THIS AFTERNOON.
DENSE...DRIER AIR OFF OF LAKE HURON IS THEN EXPECTED TO PRECONDITION
AREAS TONIGHT FOR A PRECIPITOUS DROP IN TEMPERATURES AFTER SUNDOWN.
FAVORABLE RADIATIVE COOLING CONDITIONS WILL ALLOW TEMPERATURES TO
DROP TOWARD THE FREEZING MARK IN THE THUMB TONIGHT. FROST HEADLINES
WILL EVEN NEED TO BE CONSIDERED FOR MUCH OF THE REMAINDER OF
SOUTHEASTERN MICHIGAN. WILL ALLOW THE DAY SHIFT TO WATCH
OBSERVATIONS AND MODEL TRENDS THIS AFTERNOON TO MAKE ANY
FROST/FREEZE HEADLINE DECISIONS.

LONG TERM...SATURDAY THROUGH THURSDAY

A NOTABLE SHIFT IN THE LONGWAVE PATTERN WILL BRING WARMTH AND
MOISTURE BACK TO THE GREAT LAKES THIS WEEKEND THROUGH THE UPCOMING
WEEK. THE DOMINATE UPPER LOW PARKED OVER HUDSON BAY WILL BECOME
PROGRESSIVE...TRACKING OFF TO THE EAST ON FRIDAY... THEN REACHING
THE EAST COAST ON SATURDAY. THIS SHIFT WILL ALLOW MID/UPPER LEVEL
RIDGE TO BUILD INTO THE MIDWEST WHILE AMPLIFYING SLIGHTLY. MEANWHILE
AT THE SFC A DOME OF HIGH PRESSURE WILL BE SLIDING INTO THE OHIO
VALLEY FOR THE WEEKEND. THIS WILL AT FIRST PRESENT A WEAK WAA
PATTERN WITH NW FLOW ALOFT BECOME MORE WESTERLY WITH THE RIDGE
BUILDING IN AND HEIGHTS ON THE RISE. CLEAR SKIES WILL HELP MAXIMIZE
LATE MAY INSOLATION AND WITH 850MB TEMPS RISING TO AROUND
8C...SHOULD HELP TEMPS RISE BACK INTO THE LOW 70S.

ANOTHER JUMP IN TEMPERATURES ON SUNDAY AS FLOW TURNS MORE SWERLY
WITHIN THE THERMAL RIDGE LIFTING INTO THE REGION. THIS REGION WILL
BECOME THE WARM SECTOR TO THE ELEVATED WARM FRONT ADVERTISED TO
DEVELOP OVER MID MI SUNDAY NIGHT. 850MB TEMPS WILL BE ON THE RISE
APPROACHING 11C BY SUNDAY EVENING. TEMPS SHOULD RISE INTO THE MID
70S. A GOOD DEAL OF MOISTURE ALOFT WILL ADVANCE INTO THE AREA AS SEE
IN THE TIGHT MID LEVEL THETA E GRADIENT SATURDAY NIGHT. DRY AIR IN
THE LOWEST 10KT WILL KEEP THE AREA DRY THROUGH INTO THE DAY SUNDAY
THOUGH. BETTER SURGE OF MOISTURE TAKING PWATS FROM 1.3 INCHES TO 1.7
INCHES...PER GFS BUFKIT SOUNDINGS /1.6 INCHES PER NAM/...ON SUNDAY
WITH THE HELP OF THE STRENGTHENING SWERLY LL JET. FAVORABLE REGION
OF THE JET WILL BE TO OUR NW WHICH LEAVES US WITH THE SFC WARM FRONT
LIFTING THROUGH THE REGION LATE IN THE DAY. ITS UNSURE HOW FAR EAST
INTO THE DEPARTING SFC RIDGE CONVECTION WILL BE ABLE TO FIRE SO WILL
MAINTAIN SLIGHT CHANGE POPS SUNDAY DURING THE DAY AS I THINK THE
BULK OF THE DAY WILL BE PLEASANT AND DRY FOR MOST LOCATIONS. LIKELY
POPS OVERNIGHT AS BOUNDARY LAYER SATURATES AND LL LAPSE RATES RISE.

NOT MUCH CLARITY TO GIVE FOR THE FIRST HALF OF THE UPCOMING WORK
WEEK. WE REMAIN IN THE WARM SECTOR AHEAD OF THE MID LEVEL TROUGH
OVER THE NORTHERN/CENTRAL PLAINS WITH GOOD FEED OF WARM MOIST AIR
INTO THE AREA. A SERIES OF WAVES WILL EXIT THE TROUGH AND TRAVERSE
THE AREA PRESENTING SEVERAL OPPORTUNITIES FOR SHOWERS AND
THUNDERSTORMS. WILL BE ABLE TO ADD MORE DETAIL TO THIS PORTION OF
THE FORECAST AS THE WAVES BEGIN TO SHOW UP ON SATELLITE.
REGARDLESS...LOOKS LIKE TEMPS WILL HOVER AROUND 80 FOR THE BETTER
PART OF THE WEEK.

MARINE...

SLIGHTLY ELEVATED WINDS AND WAVES BEHIND A COLD FRONT DROPPING INTO
THE OHIO VALLEY WILL DROP OFF QUICKLY TODAY AS HIGH PRESSURE BUILDS
IN QUICKLY THROUGH THE AFTERNOON. THIS AREA OF HIGH PRESSURE WILL
HOLD THROUGH SATURDAY AND INTO SUNDAY PROVIDING FOR FAVORABLE
BOATING CONDITIONS. CHANCES OF SHOWERS AND THUNDERSTORMS RETURN
SUNDAY EVENING...PERSISTING INTO THE BEGINNING OF NEXT WEEK.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
&&

$$

AVIATION.....CB
SHORT TERM...CB
LONG TERM....DRK
MARINE.......DRK


YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).



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