Severe Thunderstorm Warning 52, NWS Detroit, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
330 PM EDT TUE JUN 20 2000

KDTX 88D INDICATING THAT ECHOS ARE BECOMING MORE WIDESPREAD ACROSS
THE SAGINAW REGION.  SO FAR, NOT MUCH HAS REACHED THE GROUND.  WITH
SURFACE DEWPOINTS NOW RISING QUICKLY ACROSS SOUTHWEST LOWER, AS THE
WARM FRONT CONTINUES TO SLIP NORTHWARD, EXPECT THAT THE COVERAGE
WILL CONTINUE TO INCREASE AS THE DEEP MOISTURE AND BETTER LIFT WORKS
INTO THE AREA OVER THE NEXT COUPLE OF HOURS.  THE WIDESPREAD THUNDER
HAS, FOR THE MOST PART, REMAINED OVER ILLINOIS IN THE VICINITY OF
THE STRONGEST 700MB THETA-E ADVECTION.

NCEP OFFERING THIS CYCLE CONTINUES AN ACCELERATED TREND.  THE AVN
HAS NOW COME IN LINE WITH THE PERSISTENT ETA-32 TIMING.  PREFER
THE QPF DEPICTION OF THE 12Z NSSL ETA-32 AND THE DTX ETA-50 RUNS
(WHICH BOTH USE THE KAIN-FRITSCH CU SCHEME) OVER THE NCEP ETA-32
(BMJ SCHEME).  THE STRONG THETA-E ADVECTION, PREVIOUSLY MENTIONED,
IN THE 850-700MB LAYER WILL AFFECT THE CWFA DURING THE EVENING
HOURS, USHERING IN THE DEEP TROPICAL MOISTURE.  PWATS SURGE TO 1.8
INCHES OVER MOST OF SE LOWER OVERNIGHT.  THE DEEP MOISTURE WITH EVEN
MODEST LIFT SHOULD CONTINUE SUPPORT NUMEROUS SHOWERS.  THUNDER WILL NOT BE
WIDESPREAD, BUT CERTAINLY NOT OUT OF THE QUESTION AS THE COLD FRONT
AND SOME 850 FGEN WILL ENHANCE UPDRAFT STRENGTH.  CAPES TO WORK WITH
WILL BE MINIMAL TONIGHT, SO EXPECT MAINLY GOOD RAINERS.  KF-ETA RUNS
PRODUCE CLOSE TO AN INCH IN MANY SPOTS WITH THE BMJ-ETA ONLY AROUND
FOUR TENTHS.

ALL THE PROGS INDICATE THAT THE SURFACE FRONT WILL BE CLEAR OF THE
CWFA BEFORE 15Z.  AS A RESULT WILL CARRY A LINGERING CHANCE FOR
SHOWERS THROUGH MID-MORNING.  DEEP MOISTURE SCOURS OUT RAPIDLY
BEHIND THE COLD FRONT, AS EVIDENCED BY VIS IMAGERY.  HOWEVER, THERE
MAY BE ENOUGH RESIDUAL LOW LEVEL MOISTURE AND SOME FRICTIONAL
(EKMAN-TYPE) CONVERGENCE TO KEEP SOME LOWER LEVEL CU AROUND,
ESPECIALLY AROUND AREAS THAT RECEIVE A GOOD AMOUNT OF RAIN.  CU
POTENTIAL FOR THURSDAY LOOKS QUITE GOOD AS THE COLD POOL SETTLES
OVERHEAD.  EXPECT THAT THE FAR SOUTH WILL REMAIN PARTLY SUNNY, BUT
NORTH OF DETROIT THE CU SHOULD CONGEST UP AND EVEN PRODUCE A FEW
SHOWERS AS THE EQUILIBRIUM LEVEL WILL BE UP NEAR 500MB.  TEMPS
SHOULD BE PERSISTENT GIVEN VALUES SEEN UPSTREAM BEHIND THE FRONT.

EXTENDED PROGS ARE TRENDING TOWARD A FASTER TROUGHIER SOLUTION AS
PER THE PREVIOUS UKMET/CMC GLOBAL/ETA-XX RUNS.  WILL DISMISS SOME OF
THE DETAILS IN THE MRF AS IT EXHIBITS SIGNIFICANT CONVECTIVE
FEEDBACK AT 108H.  THE FASTER SOLUTION TRENDS ARE ALSO SUPPORTED BY
THE NEW 12Z AVN/ETA-50/CMC GLOBAL RUNS AS WELL.  THE RESULTANT
PATTERN IS LESS AMPLIFIED WITH SEVERAL EMBEDDED SHORTWAVES ACTING ON
THE RETURN FLOW FOR THE LATTER PORTION OF THE WEEKEND.  TEMPS SHOULD
REMAIN SEASONABLE THROUGH THE PERIOD.

.DTX...NONE.

MANN