Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000 FXUS63 KDTX 300723 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 323 AM EDT THU JUN 30 2016 .DISCUSSION...
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High pressure will continue to sink south and east today as the upper trough stretched from Ontario back through Saskatchewan swings down towards the area. This trough is expected to pivot across Michigan tonight, with a quick shot of deep layer forcing and narrow theta-e plume bringing a chance for showers and thunderstorms late. Until then, model forecast soundings look capped and pretty dry through the daytime heating cycle today, and continue to support a dry forecast. Temperatures will continue to warm today, with max temps fairly close to 80. Frontal boundary is expected to push across the area between 1AM and 10AM. Low-level FGEN, mid-level PVA, and left exit region forcing will support the chance for showers and thunderstorms along the front. Instability overall still does not look great but better than 24 hours ago. NAM cross-sections show a shallow layer of steep lapse rates (750-850mb) positioned just above the FGEN layer. GFS/NAM also now show a weak corridor of 25-30 kt low-level winds feeding into southern Lower Michigan late, with warm air advection through this layer likely boosting the elevated instability. Current radar shows an area of showers (earlier there were thunderstorms) along the front over Minnesota and Lake Superior. This raises confidence that forcing should be strong enough to generate showers later tonight despite very dry airmass preceding the system. Kept pops at high chance however until we can see effects of diurnal heating cycle upstream, although confidence is higher for south-central Lower Michigan closer to the upper wave and cooler air aloft. Window for showers will be short, with activity most likely only affecting each location for a few hours. Negative showalter indices and models kicking out a few hundred j/kg of CAPE continue to support low thunder chances tonight and early Friday before showers/tstorms exit east with the cold front. High pressure should provide dry and quiet weather Friday evening through Sunday night. Max temperatures will take a slight hit behind the front, then moderate back up around 80 again by Sunday. Upper wave lifting through the Ohio Valley now needs to be closely watched for potential to impact the forecast for the Fourth of July holiday and Monday night. All medium-range models have made a jog to the north with the wave, although the GEM remains a northerly outlier. For now consensus forecast with low chance pops from Detroit southward looks appropriate for late Monday and Monday night. Upper ridge is still favored to build into the area for the middle of the week, allowing heat and humidity to seep back into the area.
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&& .MARINE...
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Marine wind will remain light and generally from the south today prior to the passage of a cold front tonight. This front will bring a pattern of showers and a few thunderstorms through the region after midnight through Friday morning. Moderate northwest wind will develop behind the front, especially over northern and central Lake Huron. Wind speed and wave height remain below small craft advisory levels over southern Lake Huron before high pressure arrives Saturday and remains in place through the holiday weekend.
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&& .PREV DISCUSSION...
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Issued at 1215 AM EDT Thu Jun 30 2016 AVIATION... Scattered high clouds will continue to flow across the region tonight, and likely through the day. Winds will be light and variable tonight and will resume a more southwesterly component during the morning, but will remain rather tame - 10 knots or less. VFR clouds will increase Thursday evening hours as a cold front encroaches from the west. For DTW...the incoming ceilings Thursday night will flirt with 5kft after midnight, but rain chances will be confined to the near dawn hours on Friday. //DTW Threshold Probabilities... * Moderate confidence in ceilings aob 5kft after 04z Thursday Night
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&& .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ DISCUSSION...HLO MARINE.......BT AVIATION.....Mann You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.

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