National Weather Service Raw Text Product
Displaying AFOS PIL: AFDDTX Received: 2018-04-25 19:21 UTC
754 FXUS63 KDTX 251921 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 321 PM EDT Wed Apr 25 2018 .DISCUSSION... Partial clearing across the southern Metro region have allowed temperatures to overachieve this afternoon as temperatures have climbed into the lower 60s. Northerly flow off of Lake Huron have kept temperatures capped in the 40s across the Thumb, while more moderate temperatures have been observed from Pontiac up to Saginaw, with highs in the 50s. Communities in the thumb, especially closer to the shoreline, will have a slight chance to see brief showers through the evening as a PV anomaly resides across central Lake Huron. Cloud cover associated with this eastward moving PV anomaly and diurnal heating will begin to diminish tonight and overnight as incoming subsidence and dry air settles in across SE MI. Winds gusting between 15 - 20 mph, isolated 25 mph, will also quickly diminish tonight after diurnal mixing ceases after sunset. The cut- off low and associated PV anomaly will push over New York by Thursday 12Z and will continue to reinforce NW flow across Michigan, allowing 850 mb temperatures to drop to an average of 1C overnight. Clear skies will allow for strong radiational cooling overnight, supporting lows in the lower 30s across SE MI and mid-30s across the urban Metro region. A very slight chance for periods of patchy fog to develop overnight across the Thumb, as winds diminish and dry air moves in aloft, however, opted to leave patchy fog out of the official forecast as latest high-resolution runs keep surface conditions too dry to support fog chances. Otherwise, a ridge of high pressure will then build across Michigan throughout Thursday and will continue to keep conditions dry as clear to partly clouds skies persist throughout the day. Copious amount of sunshine will allow temperatures to push into the low to mid-60s for a daytime high as a weak pressure gradient keep winds calm to light. The next chance for rain will enter late Friday morning into the early afternoon as an upper-level trough and associated cold front push through the Great Lakes region. Temperatures will remain below- normal as a thermal trough and overcast conditions help cap daytime highs to the mid to upper 50s Friday afternoon. For reference, normal highs reside in the lower-60s for late April. Otherwise, a brief lull in precipitation will be possible late Friday afternoon, before an embedded shortwave located on the backside of a trough coupled with left exit dynamics from a jet maxima aloft help support a second round of showers. Rain chances will be centered across the Metro region, late Friday into Saturday morning. Any lingering showers will be on the way out by Saturday afternoon as upper jet support and shortwave move off to the east. Strong ridging through the troposphere will take over in the wake and high pressure at the surface will dominate the weekend forecast. Thermal trough with 850 mb temps in the negative single digits C will linger through Saturday and limit surface highs to the low 50s. Quick modification of this air mass in late April insolation will allow Sunday's highs to rise to the mid 50s. Dry and mostly sunny conditions will prevail Saturday through late Tuesday as the high pressure slowly drifts south and east. Warm air advection will become established by Monday with southerly flow bringing highs to the upper 60s that day, and the lower 70s by midweek. Chance for rain returns on Wednesday due to low pressure over Ontario pushing a cold front through the Great Lakes. && .MARINE... Small craft advisories remain in effect for Saginaw Bay and southern Lake Huron through this evening. Peak gusts topping out near 25 knots will relax through the evening as low pressure tracks east to southern Ontario but the long north fetch will keep waves elevated in excess of 4 feet for several more hours. High pressure will build overhead tonight and hold through Thursday resulting in light winds backing from northwest to southwest. A cold front will then reach northern Lake Huron late Thursday night and sweep across the rest of the basin through the day Friday. This combined with an additional low pressure system sweeping across the southern lakes will keep unsettled conditions and gusty northerly flow through the weekend. && .PREV DISCUSSION... Issued at 112 PM EDT Wed Apr 25 2018 AVIATION... Low pressure will track down the axis of Lake Huron through the afternoon which will keep MVFR CIGS around into the evening. Meanwhile, dry air over the western side of the state will be encroaching through that time helping to scatter out the clouds from west to east. The terminals look to fall near the western edge of the thicker clouds which could lead to brief fluctuations into VFR over the course of the late afternoon. Skies will clear and winds will become light tonight as high pressure builds into the region. Still some signals that a brief period of shallow MVFR could develop as nocturnal min temps are reached toward morning. For DTW... Wind direction stays consistent from the NNW in the 10 to 15 knot range and likely requires NE traffic flow operations. Winds will drop off while becoming more westerly around midnight allowing more favorable SW flow operations. DTW THRESHOLD PROBABILITIES... * High for ceiling 5000 ft or less into this evening. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...Small Craft Advisory until 10 PM EDT this evening for LHZ421- 441>443. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ DISCUSSION...AM/TF MARINE.......DK AVIATION.....DK You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.