497
FXUS63 KDTX 011718
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
118 PM EDT FRI MAY 1 2026
KEY MESSAGES
- SCATTERED RAIN SHOWERS ARE POSSIBLE THIS AFTERNOON.
- A FREEZE WARNING IS IN EFFECT FOR ALL OF SOUTHEAST MICHIGAN
TONIGHT.
- DRIER CONDITIONS EXPECTED SATURDAY AND EARLY SUNDAY BEFORE RAIN
AND THUNDERSTORM CHANCES RISE EARLY NEXT WEEK.
AVIATION
LIGHT NORTHWEST WINDS (UP TO AROUND 10 KNOTS) THIS AFTERNOON BRINGS
MODEST DRIER AIR, LIFTING CLOUD BASES 4-8 KFT RANGE. SEASONALLY COLD
AIR ALOFT AND DIURNAL HEATING WILL STILL OFFER UP ISOLATED-SCATTERED
LIGHT SHOWERS THIS AFTERNOON INTO EARLY EVENING HOURS. LEFT A
RESIDUAL MID CLOUD DECK IN FOR THE OVERNIGHT HOURS, BUT CONFIDENCE IS
LOW, AND MAY END UP BEING MOSTLY CLEAR. DIURNAL HEATING TOMORROW
LIKELY LEADS TO SOME VFR FLAT CU, AND MAY BE ENOUGH TO PRODUCE CIGS
OVER SOUTHERN TAFS WHERE THERE IS A LITTLE BETTER MOISTURE.
D21/DTW CONVECTION...NO THUNDERSTORMS EXPECTED THROUGH THIS TAF
PERIOD.
DTW THRESHOLD PROBABILITIES
* MEDIUM FOR CIGS AOA 5000 FEET THROUGH THIS EVENING, THEN LOW.
PREV DISCUSSION
ISSUED AT 321 AM EDT FRI MAY 1 2026
DISCUSSION...
THE MERGER OF THE NORTHERN AND SOUTHERN STREAM WAVES HAS SUPPORTED
AN EXPANSIVE JET STREAK, OCCUPYING A SIGNIFICANT PORTION OF EASTERN
CONUS. SOUTHEAST MICHIGAN RESIDES ALONG THE NORTHERN FRINGE OF THE
LONGWAVE FEATURE AS A MID-/UPPER-LEVEL LOW SLOWS OVER CENTRAL
ONTARIO, DEFLECTING AGAINST NORTHWARD PROGRESS OF THE COMPOSITE
WAVE. HOWEVER, PERTURBED FLOW ALOFT SUSTAINS A SERIES OF SHORTWAVE
EJECTIONS OVER THE GREAT LAKES DURING THE NEXT 48 HOURS. THE INITIAL
TROUGH IS CURRENTLY TRANSITING NORTHERN INDIANA/OHIO, SHOVING ITS
SURFACE REFLECTION EASTWARD TOWARD THE SOUTHERN LAKE ERIE SHORELINE.
EARLY MORNING RADAR AND SURFACE OBSERVATIONS REVEAL A WEAK
PRECIPITATION RESPONSE FROM THE VICINITY DISTURBANCE, LARGELY
INHIBITED BY A LACK OF DEEP-LAYER MOISTURE AS EVIDENCED BY THE
01.00Z KDTX RAOB. SHOWERS SHOULD CONTINUE FOR SEVERAL MORE HOURS,
PREDOMINANTLY SOUTH OF THE I-96/I-696 CORRIDOR, UNTIL ABOUT 15Z. FOR
THE REST OF TODAY, A LOBE OF VORTICITY EXTENDING FROM THE RESIDENT
CLOSED LOW OFFERS A BOOST TO ASCENT, AND AN OPPORTUNITY FOR
SCATTERED NARROW-DIAMETER SHOWERS. FORECAST SOUNDINGS IDENTIFY
SURFACE-BASED MIXING DEPTHS MAXIMIZING SOME 8-10 KFT AGL THIS
AFTERNOON, EXTENDING INTO THE DGZ. HYDROMETEOR PATHS FACE WARM AND
DRY AIR WITHIN THE FINAL THIRD OF DESCENT. THIS SUGGESTS MELTING AND
EVAPORATION CONCERNS, WHICH SHOULD LIMIT QPF AND AFFORD AREAS OF
VIRGA. SHOWERS WANE IN THE ABSENCE OF A DIURNAL BOUNDARY-LAYER.
THE CURRENT CONFIGURATION REINFORCES LOWER COLUMN NNW FLOW WITH
THERMAL TROUGHING SENDING 850 MB TEMPERATURES DROPPING INTO THE -3C
TO -7C RANGE TONIGHT. REGARDING THE FREEZE WATCH, UNCERTAINTY
REGARDING CLOUD TRENDS PRECLUDES ANY UPGRADES TO THE INHERITED
WATCH. THE LATEST MODEL DATA INDICATES AREAS TO THE NORTH/WEST FACE
A HIGHER LIKELIHOOD TO EXPERIENCE SUFFICIENT CLEARING AND SUBSEQUENT
LONGWAVE COOLING. ADDITIONALLY, GRADIENT WINDS APPEAR TO TREND
TOWARD CALM SOON FOR WESTERN LOCATIONS GIVEN THE EMERGENCE OF
SURFACE RIDGING FROM THE UPPER MIDWEST.
WHETHER OR NOT FREEZE CRITERIA IS REACHED, SATURDAY WILL GET OFF TO
A CHILLY START, BY EARLY MAY STANDARDS. TEMPERATURES AT SUNRISE WILL
BE IN THE 30S FOR MOST LOCATIONS, OR 10F TO 15F BELOW NORMAL. A
MOSTLY DRY DAY IS FORECAST AS THE NEXT ROUND OF CVA MOVES OVERHEAD
WITH LIMITED FANFARE. PWATS DECREASE, DROPPING BELOW 0.30 INCHES,
WITH JUST A 2-4 KFT SATURATED LAYER, CENTERED NEAR 7 KFT AGL. A FEW
ISOLATED SHOWERS/SPRINKLES ARE POSSIBLE DURING PEAK HEATING, BUT
PROFILES LOOK TOO LEAN (EXCLUDING THE OPERATIONAL GFS) TO INCLUDE
EVEN SLIGHT CHANCE POP ADJUSTMENTS. HIGH PRESSURE BUILDS ACROSS LAKE
MICHIGAN DURING THE DAY, FOLLOWED BY HEIGHT RISES ALOFT.
TEMPERATURES RECOVER INTO THE LOW 50S, BOOSTED BY A RISING SUN ANGLE
WHILE RATHER LIGHT GRADIENT FLOW HOLDS FROM THE NORTHWEST.
MID-LEVEL WINDS BACK ZONALLY ON SUNDAY WITH AN UPTICK IN THETAE
WHILE SURFACE WINDS FLIP SOUTHWESTERLY. SURFACE RIDGING CENTERS MUCH
FURTHER SOUTH, WELL INTO THE SOUTHEAST AS A MORE ACTIVE PERIOD GETS
UNDERWAY ACROSS MICHIGAN. CONFLUENT LOW-LEVEL FLOW LEADS TO BREEZY
AND POSSIBLY SOME SHOWERY CONDITIONS. A PROGRESSIVE ALASKAN WAVE
DESCENDS ON THE REGION MONDAY PRODUCING A DEEPENING SURFACE LOW, TO
982 MB. AN ELONGATED COLD FRONT EXTENDS FROM CENTRAL ONTARIO INTO
THE SOUTHERN PLAINS WHICH WILL FOCUS A LARGE SWATH OF SHOWERS AND
THUNDERSTORMS MONDAY NIGHT INTO TUESDAY. PRE-FRONTAL WARM SECTOR
BRINGS A BRIEF REPRIEVE FROM SEASONABLY COOLER WEATHER. TIMING OF
THE EVOLUTION OF THESE FEATURES LEAVES MANY QUESTIONS AS TO HOW
ACTIVE THE MID-WEEK TIME-FRAME WILL BECOME.
MARINE...
A SLOW MOVING UPPER-LEVEL LOW PRESSURE SYSTEM WILL CONTINUE TO
IMPACT THE GREAT LAKES THROUGH THE END OF THE WEEK. THIS WILL BRING
PERIODIC RAIN SHOWER ALONG WITH LIGHTER WINDS GIVEN THE DIFFUSE
PRESSURE GRADIENT. WIND DIRECTION HOLDS FROM THE NORTH TO NORTHWEST
THROUGH THE END OF THE WEEK WITH LOCALIZED HIGHER WINDS SPEEDS FOUND
ALONG NORTHERN LAKE HURON, WITH GUST POTENTIAL UP TO AROUND 20 KNOTS.
WIND DIRECTION BACK TO THE SOUTHWEST SUNDAY AND HOLDS THROUGH EARLY
NEXT WEEK AS A WARM FRONT PASSES THROUGH THE GREAT LAKES. THINGS
BRINGS ADDITIONAL CHANCES FOR RAIN SHOWERS AND A LOW CHANCE FOR AN
EMBEDDED THUNDERSTORM.
DTX WATCHES/WARNINGS/ADVISORIES
MI...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT SATURDAY FOR
MIZ047>049-053>055-060>063-068>070-075-076-082-083.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
AVIATION.....SF
DISCUSSION...KGK
MARINE.......AM
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