Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 270750
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
350 AM EDT MON JUL 27 2015

.SHORT TERM...TODAY AND TONIGHT

STEADY AMPLIFICATION OF THE SOUTHERN PLAINS UPPER RIDGE INTO THE
GREAT LAKES OVER THE NEXT 24 HOURS WILL PROVIDE THE MAIN BACKDROP
FOR CONTINUED ABOVE NORMAL WARMTH THROUGH THIS TIME.  DEEP LAYER
SUBSIDENCE AND RESULTANT GREATER STABILITY WITH HIGH PRESSURE LOCKED
IN AT THE SURFACE WILL ENSURE PLENTY OF SUNSHINE TODAY.  THIS WILL
SUPPORT A SLIGHT UPWARD TREND IN TEMPERATURES RELATIVE TO YESTERDAY.
HIGHS UPPER 80S/NEAR 90.  DEEPER MOISTURE AXIS WILL RESIDE TO THE
SOUTH AND WEST...WITH DEWPOINTS HOLDING AROUND 60F.  THIS WILL
LARGELY CONTAIN HEAT INDICES TO WITHIN A DEGREE OR SO OF THE ACTUAL
TEMPERATURE.  A CLEAR SKY WITH MILD CONDITIONS TONIGHT.  LOWS MAINLY
LOWER AND MIDDLE 60S.

&&

.LONG TERM... TUESDAY THROUGH NEXT SUNDAY

HIGH PRESSURE AT THE SURFACE WILL LARGELY MAINTAIN ITS
POSITION/INFLUENCE OVER THE GREAT LAKES FOR MUCH OF THE EXTENDED
FORECAST. A COLD FRONT WILL SWEEP THROUGH THE REGION ON WEDNESDAY
PUSHING THE CURRENT HIGH OFF TO THE EAST BUT THE NEXT HIGH WILL
QUICKLY RETURN IN ITS WAKE. BIGGER CHANGES WILL COME WITH THE
MID/UPPER LEVEL PATTERN THROUGH THE FORECAST. A STRONG WAVE COMING
ASHORE THE NW CONUS WILL DEEPEN THE WEST COAST TROUGH AND IN RETURN
WILL AMPLIFY THE RIDGE AXIS OVER THE CENTAL PLAINS. AS IT WORKS EAST
ACROSS THE US/CANADA BORDER...THE RIDGE AXIS WILL SLIDE OVER THE
GREAT LAKES. THIS WILL INTRODUCE 500MB HEIGHTS AROUND 590 DAM ON
TUESDAY AND INTO WEDNESDAY. LOOKING LOWER IN THE COLUMN...THE 850MB
TEMPS WHICH HAVE BEEN HOVERING IN THE MID TEENS WILL INCREASE TO THE
UPPER TEENS. THIS SHOULD ALLOW TEMPS TO INCREASE A COUPLE DEGREES
OFF THE MID/UPPER 80S WE HAVE BEEN STUCK ON FOR SEVERAL DAYS
NOW...TO AROUND 90 TUESDAY. AFTER THE WAVE PASSES...THE LONGWAVE
PATTERN WILL SWITCH FROM COASTAL TROUGHS WITH CENTRAL CONUS
RIDGE...TO WESTERN CONUS RIDGE AND EASTERN CONUS TROUGH. THIS WILL
BRING AN END TO THE HIGH 80S WE HAVE BEEN DEALING WITH FOR THE LAST
WEEK.

WEDNESDAYS TEMPERATURES WILL BE A BIT TOUGHER AS IT WILL BE VERY
DEPENDENT ON THE TIMING OF A COLD FRONT AND AMOUNT OF CLOUD COVER
PRESENT. THE AFOREMENTIONED WAVE WILL LIFT NE THROUGH ONTARIO WITH
THE COLD FRONT SHEARING/WEAKENING AS IT TRAVERSES LOWER MI. WITH SW
RETURN FLOW AHEAD OF THE FRONT AND THE RESIDENT AIRMASS IN
PLACE...TEMPS SHOULD HAVE NO PROBLEM REACHING THE MID/UPPER 80S ONCE
AGAIN. THERE WILL LIKELY BE A GRADIENT FROM N TO S AS CLOUDS BEGIN
MOVING IN EARLY ACROSS THE SAGINAW VALLEY. SO AT THIS TIME WILL
HEDGE TOWARD THE PERSISTENCE FORECAST WHILE KEEPING ON EYE ON THE
TIMING OF THE FRONT AND CLOUDS.

THE OTHER ISSUE ON WEDNESDAY IS THE POTENTIAL FOR SHOWERS AND
THUNDERSTORMS ALONG AND AHEAD OF THE FRONT. THOUGH THE FRONT IS
WEAKENING AS IT PASSES THROUGH THE STATE...SUMMER HEAT...RIBBON OF
HIGH MOISTURE CONTENT AHEAD OF THE FRONT WITH MODEL PWATS OVER 2
INCHES...GOOD LL LAPSE RATES...AND MLCAPE IN EXCESS OF 1500
J/KG...WE STAND A DECENT CHANCE OF SPARKING A FEW THUNDERSTORMS WITH
AN AFTERNOON FRONTAL TIMING. SHEAR WILL BE LESS THAN IMPRESSIVE AT
AROUND 20 KNOTS...BUT THAT WILL STILL BE ENOUGH TO POSSIBLY ALLOW A
FEW STORMS TO GAIN SOME ORGANIZATION. AND IF THE HIGH PWATS BECOME
REALIZED HEAVY RAIN POTENTIAL WILL BE HIGH. SOMETHING TO WATCH IN
THE COMING DAYS.

HIGH PRESSURE RETURNS ON THURSDAY UNDER THE DEVELOPING LONGWAVE
TROUGH...AND WILL HOLD INTO THE WEEKEND. THE NEXT SHOT FOR PRECIP
LOOKS TO COME ON SATURDAY AS A SHORTWAVE TRACKS DOWN THE NW FLOW
THROUGH SOUTHERN CANADA PULLING A WEAK TROUGH INTO THE GREAT LAKES.

&&

.MARINE...

SURFACE HIGH PRESSURE WILL MAINTAIN LIGHT WIND CONDITIONS TONIGHT.
SOUTHWEST WINDS WILL INCREASE MODESTLY ON WEDNESDAY AS A COLD FRONT
APPROACHES FROM THE WEST.

&&

.AVIATION...ISSUED 1151 PM EDT SUN JUL 26 2015

THE LOW LEVELS HAVE DRIED OUT TODAY...BUT CAN NOT TOTALLY RULE OUT A
SHORT WINDOW OF LIGHT (3-5SM) FOG LATE TONIGHT...BUT PLANNING ON
LEAVING OUT OF TAFS DUE TO LOW PROBABILITY OF OCCURRENCE.

OTHERWISE...HIGH PRESSURE OVER THE REGION THROUGH TOMORROW NIGHT
WILL PRODUCE MAINLY CLEAR SKIES AND VERY LIGHT WINDS THROUGH THE TAF
PERIOD...WITH JUST A FEW CU (5000 KFT) TOMORROW AFTERNOON.

//DTW THRESHOLD PROBABILITIES...

* NONE.

&&

.PREV DISCUSSION...ISSUED 308 PM EDT SUN JUL 26 2015

WEAKENING SHORTWAVE OVER SOUTHERN WI WILL CONTINUE TO SHEAR OUT IN
THE RELATIVELY FASTER FLOW TO ITS EAST. DEBRIS CI AND AC WILL MOVE
OVER SE MI LATE THIS AFTERNOON AND INTO THE EVENING AND WILL GO WITH
A PARTLY CLOUDY SKY. AFTER 03Z...SKIES WILL BECOME CLEAR AGAIN.  THE
ONE EXCEPTION MAYBE THE TRI CITIES AND THUMB REGIONS AS SOME AC
MOVES DOWN FROM THE NW TOWARD DAYBREAK. DO NOT EXPECT THE SAME FOG
ISSUES GIVEN THE FULL DAY OF DRYING WITH FULL SUNSHINE AND DEW
POINTS FALLING IN THE UPPER 50S AND LOWER 60S. MET/NAM GUIDANCE IS
LOWER THAN THE MAV/GFS FOR TONIGHTS LOWS. WILL LEAN TOWARD THE
MET/NAM GIVE THE CURRENT DEW POINTS AND MOSTLY CLEAR SKIES FOR THE
BULK OF THE NIGHT.

LONG TERM... MONDAY THROUGH NEXT SUNDAY

MEANDERING SURFACE HIGH PRESSURE WILL MAINTAIN SERVE THROUGH TUESDAY
UNDERNEATH BUILDING MID/UPPER LEVEL HEIGHTS. COLUMN DEEP SUBSIDENCE
WILL PROMOTE A GRADUAL INCREASE IN LOWER TROPOSPHERIC TEMPERATURES.
SHOULD BE ENOUGH TO HELP GRAB A DEGREE OR TWO MORE EACH DAY AT THE
SURFACE - HIGHS NEAR 90F EACH DAY. WITH THE SURFACE HIGH CENTER IN
RESIDENCE...NEAR SURFACE MOISTURE WILL BE VERY LIMITED UNTIL RETURN
FLOW SETS UP ON WEDNESDAY IN ADVANCE OF THE NEXT FRONT TO INFLUENCE
THE REGION.  THEREFORE...NOT EXPECTING MUCH IN THE WAY OF DIURNAL
CUMULUS EITHER DAY AND THE HEAT INDEX WILL NOT DEVIATE MUCH FROM THE
OBSERVED TEMPS.

WAVE CRASHING INTO PACIFIC NORTHWEST WILL DRIVE RESPECTABLE
CYCLOGENESIS ACROSS THE NORTHERN PLAINS MONDAY NIGHT. THE RESULTANT
MID-LATITUDE CYCLONE WILL LIFT NORTHEAST TO HUDSON BAY DRAGGING A
WEAKENING COLD FRONT ACROSS THE GREAT LAKES REGION ON WEDNESDAY.
RAIN AND THUNDER CHANCES ACROSS SOUTHEAST MICHIGAN HINGE ON THE
CHARACTER OF TUESDAY/S CONVECTIVE RESPONSE OVER THE UPPER
MISSISSIPPI VALLEY. NWP SUITE SUGGESTS SOME SORT OF WANING COVERAGE
CONVECTIVE SYSTEM WANDERING EAST ACROSS THE LOWER PENINSULA WITH THE
POSSIBILITY OF DIURNAL DEVELOPMENT RE-ENFORCEMENT DURING WEDNESDAY
AFTERNOON BEFORE EXITING STAGE RIGHT OVER ONTARIO.

SHOULD BE SOME REASONABLE BUILDING UP OF CAPE AS A RIBBON OF
ENHANCED THETA-E SQUEEZES NORTH IN ADVANCE OF THE COLD FRONT -
HOWEVER...NOT NECESSARILY TO THE TUNE OF THE NAM/S 3.8 KJ/KG OF 0-
1KM MLCAPE.  MORE LIKELY TO SEE MLCAPE IN THE 2 KJ/KG NEIGHBORHOOD.
THE LACK OF FLOW...THEREBY SUBSEQUENT LACK OF SHEAR...IN THE WARM
SECTOR WILL CERTAINLY ENCOURAGE LOOSELY ORGANIZED MULTI-CELLS - WITH
ENOUGH INSTABILITY TO SUGGEST A NON-NEGLIGIBLE WET MICROBURST
POTENTIAL.

HIGH PRESSURE EXPECTED TO NOSE IN THURSDAY AND FRIDAY PROVIDING DRY
WEATHER WITH SEASONABLE TEMPS. 12Z GFS/EURO DEPICT UPPER HEIGHTS
FALLING SLIGHTLY NEXT WEEKEND WHICH ARGUES FOR CHANCE POPS.

MARINE...

SURFACE HIGH PRESSURE WILL MAINTAIN LIGHT WIND CONDITIONS THROUGHOUT
TUESDAY. SOUTHWEST WINDS WILL INCREASE MODESTLY ON WEDNESDAY AS A
COLD FRONT APPROACHES FROM THE WEST.

&&

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

$$

SHORT TERM...MR
LONG TERM....DRK
MARINE.......DRK
AVIATION.....SF


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



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