Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 231715
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
115 PM EDT WED APR 23 2014


.AVIATION...

//DISCUSSION...

HIGH PRESSURE SETTLING INTO THE REGION WILL BRING VFR CONDITIONS
THROUGH 00Z FRIDAY. NORTHERLY WINDS WILL ALSO DECREASE IN SPEED
TODAY...WITH GUSTS TO 15 KNOTS DROPPING OFF BY LATE
AFTERNOON...BEFORE BECOMING LIGHT AND VARIABLE OVERNIGHT. HIGH/MID
CLOUDS WILL INCREASE AND THICKEN OVERNIGHT AND THURSDAY AHEAD OF AN
APPROACHING LOW PRESSURE SYSTEM. RAIN FROM THIS SYSTEM IS EXPECTED
TO HOLD OFF UNTIL AFTER 00Z FRI.

//DTW THRESHOLD THREATS...

* NONE

&&

.PREV DISCUSSION...ISSUED 345 AM EDT WED APR 23 2014

SHORT TERM...TODAY AND TONIGHT

HIGH PRESSURE WILL BUILDS INTO THE CENTRAL GREAT LAKES DURING THE
COURSE OF THE DAY AND THEN SLOWLY SHIFT EAST OF THE REGION LATE
TONIGHT. WHILE THIS HIGH WILL MAINTAIN RELATIVELY COOL CONDITIONS
ACROSS THE AREA AS TEMPERATURES...LOWER TO MID 50S...REMAIN NEARLY
10F BELOW AVERAGE FOR DAYTIME MAXIMUM TEMPERATURES...IT WILL ALSO
BRINGING CLEARING SKIES AND EASING WINDS.

SO AFTER A VERY COOL START IN THE 30S...EXPECT REASONABLE DECENT
CONDITIONS BY AFTERNOON/EARLY EVENING IN MOST LOCATIONS. PORTIONS OF
THE THUMB WILL BE THE EXCEPTION AS NORTHERLY FLOW FROM COLD WATERS
WILL LIMIT HIGH TEMPERATURES TO THE 40S IN MANY CASES.

WITH THIS HIGH PRESSURE DRIFTING OVER THE AREA THIS EVENING INTO THE
OVERNIGHT HOURS...EXPECT TEMPERATURES TO DROP SIGNIFICANTLY. WILL
HAVE TO LOWER THE GOING FORECAST...PARTICULARLY OVER THE NORTHEAST
QUADRANT OF THE CWA AS TEMPERATURES FALL INTO THE UPPER 20S TO LOWER
30S WITH SUCH STRONG RADIATIONAL COOLING. AN INCREASE IN HIGH CLOUDS
ASSOCIATED WITH A DEVELOPING ELEVATED WARM FRONT TO THE SOUTHWEST OF
THE AREA WILL LIMIT COOLING FURTHER SOUTH AND WEST...SO STILL EXPECT
MID 30S OVER THE WESTERN AND SOUTHERN PERIPHERY OF THE CWA.

LONG TERM...THURSDAY THROUGH TUESDAY

BIG CHANGES IN THE LONGWAVE PATTERN THIS WEEKEND WILL RESULT IN A
DREARY WEEK TO COME WHERE TEMPERATURES LINGER IN THE LOW 50S WITH
POTENTIAL FOR A LENGTHY WET PERIOD AS WELL. CHANGES ACTUALLY BEGIN
THE END OF THIS WEEK AS A LOW AMPLITUDE UPPER LEVEL TROUGH...WITH
COMPACT BUT STRONG CLOSED CIRCULATION...MOVES OVER THE GREAT LAKES.
THIS INITIAL TROUGH WILL SHUNT THE RIDGE ALOFT OFF TO THE EAST WHILE
THE CORRESPONDING SFC LOW REPLACES HIGH PRESSURE THAT WE WILL START
THE DAY THURSDAY WITH. THE LONGWAVE PATTERN TAKES ITS INITIAL JOG
SOUTHWARD WITH THIS LEAD TROUGH BUT IT IS MERELY SETTING THE STAGE
FOR A MUCH DEEPER CLOSED SYSTEM COMING ASHORE SOUTHERN CALIFORNIA.
THIS LARGE UPPER LEVEL TROUGH WILL BECOME CUT OFF OVER THE CENTRAL
CONUS MONDAY WHICH WILL RESULT IN A SLOW DRIFT THROUGH THE MIDWEST
AND GREAT LAKES THROUGH THE WEEK. AN EXPANSIVE COLD POOL WITH 850MB
TEMPS DOWN TO -5C AND 500MB TEMPS APPROACHING -20C WILL SLOWLY WORK
THROUGH THE AREA DURING THIS TIME WHICH SHOULD KEEP TEMPS BELOW
NORMAL NEXT WEEK.

BACK TO THE END OF THIS WEEK. THURSDAY WE WILLS START OFF WITH HIGH
PRESSURE OVER THE AREA WITH THE MID LEVEL RIDGE AXIS CROSSING THE
AREA IN THE AFTERNOON. THIS SHOULD HOLD OFF THE APPROACHING SFC LOW
AND ISOTROPICALLY INDUCED SHOWERS ALONG THE LIFTING WARM FRONT.
MODELS ARE ADVERTISING A DEEP DRY LAYER UP TO 10KFT TO START THE DAY
WHICH WILL MAKE IT NEARLY IMPOSSIBLE FOR ANY MID LEVEL MOISTURE TO
MAKE IT TO THE GROUND. THEY DO ADVERTISE PWATS JUMPING FROM A THIRD
OF AN INCH TO AROUND AN INCH THURSDAY EVENING WHEN THE MOISTURE POOL
AHEAD OF THE COLD FRONT WORKS INTO THE AREA. FOR THIS WILL KEEP
PRECIP VOID OF THE AREA FOR MOST OF THURSDAY BEFORE THE BAND OF
SHOWERS MOVES THROUGH DURING THE EVENING/OVERNIGHT. SOUTHEASTERLY
FLOW DURING MOST OF THE DAY WILL KEEP THE AREA ON THE COOLER SIDE
WITH THE POTENTIAL FOR A BRIEF POP OF WARMER TEMPS LATE IN THE
AFTERNOON IF WINDS VEER A BIT MORE TO THE SW RIGHT AHEAD OF THE
FRONT. FRONTAL TIMING WILL BE KEY AS WILL THE LOCATION OF THE SFC
LOW CENTER. THE PHASING OF TWO LOWS WILL ACTUALLY BE OCCURRING WITH
THE STRONGER LOW PASSING THROUGH NORTHERN MI WHILE A SECONDARY LOW
WILL PASS JUST TO OUR SOUTH...KEEPING THE BETTER MOISTURE AND
INSTABILITY TO OUR SOUTH AS WELL. AT THIS POINT WILL KEEP TEMPS
AROUND 60. WILL ALSO CONTINUE TO LEAVE THUNDER OUT OF THE FORECAST
WITH THE FROPA DUE TO LACK OF INSTABILITY OVER THE AREA.

ON FRIDAY WE WILL BE DEALING WITH DRY SLOT WORKING INTO THE AREA
BEHIND THE COLD FRONT WHILE A SECONDARY COLD FRONT BEGINS TO DROPS
SOUTH THROUGH LOWER MI. WILL LIKELY SEE A DRY PERIOD WITH DRY AIR
AND SUBSIDENCE RIGHT BEHIND THE FRONT WITH CHANCE TYPE SHOWERS
FILLING BACK IN LATER. HEIGHT WILL BE CLIMBING SLIGHTLY AS RIDGE
DRAWS NEAR AND WESTERLY FLOW NEAR THE SFC WILL ACTUALLY ALLOW SOME
WAA TO OCCUR WHICH WILL ALLOW US TO WARM UP A BIT MORE INTO THE 60.
FROM HERE WE FIND OURSELVES ON THE CUSP OF WARM AND COLD AIR AND
ALSO WET OR DRY WEATHER. THIS DUE TO THE FACT THAT THE LEAD FRONTAL
BAND WITH THE NEXT SYSTEM SETS UP SOMEWHERE THROUGH THE OHIO VALLEY
OR LOWER MI. UNTIL WE GET SOME BETTER RESOLUTION...WILL CONTINUE TO
HIGHLIGHT A GRADIENT OF LOW POPS ACROSS THE AREA AS WE LIKELY WILL
NOT SEE 3-4 STRAIGHT DAYS OF PRECIP. STAY TUNED FOR REFINEMENTS.

MARINE...

THOUGH NORTHWESTERLY WINDS HAVE DECREASED CLOSER TO 20 KNOTS THROUGH
THE NIGHT...IT WILL TAKE SEVERAL MORE HOURS FOR THE WAVES ON LAKE
HURON TO SUBSIDE ENOUGH TO DROP THE SMALL CRAFT ADVISORY. WILL
CONTINUE TO CARRY THEM THROUGH THE MORNING HOURS. HIGH PRESSURE
CENTERING ITSELF OVER THE GREAT LAKES WILL PRODUCE LIGHT WINDS
THROUGH TONIGHT. WINDS WILL INCREASE AGAIN ON THURSDAY OUT OF THE
SOUTHEAST AS A LOW PRESSURE SYSTEM MOVES INTO THE WESTERN GREAT
LAKES. WARMER AIR WILL INCREASE STABILITY OVER THE WATERS WHICH WILL
CAP WINDS AROUND 25 KNOTS ACROSS MUCH OF LAKE HURON. WINDS WILL
SWING AROUND THE WEST ON FRIDAY AS COLDER AIR SLOWLY WORKS BACK INTO
THE AREA...BUT WINDS ARE EXPECTED TO REMAIN PREDOMINATELY BELOW 20
KNOTS.

&&

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

&&

$$

AVIATION.....HLO
SHORT TERM...DG
LONG TERM....DRK
MARINE.......DRK


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AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).




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