Area Forecast Discussion
Issued by NWS Gaylord, MI

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000 FXUS63 KAPX 050256 AFDAPX Area Forecast Discussion National Weather Service Gaylord MI 956 PM EST Thu Mar 4 2021 .UPDATE... Issued at 944 PM EST Thu Mar 4 2021 Isentropically driven mid clouds spilling out of western upper and toward Lake Michigan this evening. These clouds will continue to slide southeast overnight, overspreading much of the area by sunrise. Low level flow has backed to the northwest and we should be able to invoke at least a minor lake response later tonight with 925mb temperatures of -6C to -8C. The combination of increasing mid level clouds and at least a minor lake contribution may be enough to trigger some flurries or a few light snow showers late. You could even argue for a touch of patchy freezing drizzle given the marginal clouds temps but that appears to be a somewhat lower probability and will not include in the forecast. Temperatures will continue to drop steadily for another few hours before they level off and even come up a bit overnight with the arrival of the mid clouds. && .NEAR TERM...(Through Tonight) Issued at 331 PM EST Thu Mar 4 2021 High Impact Weather Potential: Minimal. Pattern Synopsis/Forecast: 18z surface analysis shows a 1033mb high centered north of Lake Superior with a ridge axis extending southward across western Upper/eastern Wisconsin/eastern Illinois. Michigan on the chilly side of this high but at least skies are mainly sunny across the board. A couple of anticyclonically curved bands of warm advection induced clouds can be found over northwest Ontario and starting to spill into western Lake Superior. Meanwhile multi-band lake convection remains over Lakes Michigan and Huron. Amplifying large scale pattern expected to strengthen the northwesterly jet axis across the Great Lakes tonight...with some weak height falls moving into Michigan Friday. Upstream surface ridge axis may not make much additional progress eastward...with time will begin to see some pressure falls back into Michigan from the northeast as surface pressure gradient expected to tighten up again going into Friday. Primary Forecast Concerns: Impacts of increasing isentropic ascent across the forecast area later tonight...combined with lingering low level cold air/overwater instability (925mb temperatures in the -6C to -10C range from west to east). After a clear start to the evening expect to see at least some mid clouds spreading/developing southeast into Upper Michigan later this evening and then into northern Lower after midnight. Low level flow is expected to back more to the northwest this evening (already starting on Lake Superior per satellite imagery)...though don`t expect an immediate lake response on Lake Michigan this evening. Upstream moist layer is pretty thin but there a few spotty radar returns across northwest Ontario and the Minnesota Arrowhead...and the combination of this mid cloud and an increasing lake response overnight may be enough to get some snow flurries going in spots...or some light snow showers off Lake Superior. Or maybe even some freezing drizzle depending on cloud layer temperatures which could be somewhat marginal though not totally sure on the likelihood of this scenario coming to pass. Temperatures may tank this evening under initially clear skies... light winds..and dew points mixing into the single digits this afternoon. A few lows in the single digits possible before clouds roll back in later. && .SHORT TERM...(Friday through Sunday) Issued at 331 PM EST Thu Mar 4 2021 Primary forecast concerns/challenges: Any lake effect? No big changes in the guidance since yesterday with a northwest flow aloft expected to remain in place through Sunday morning. This will be followed by building heights Sunday afternoon. It`s marginally cold enough for lake processes to take hold Friday into early Saturday but the airmass appears to be rather dry so only some lake clouds and perhaps a few passing flurries are expected. Partly to mostly cloudy Friday morning, otherwise most spots should see a good deal of sunshine through the period. Temperatures will be a few degrees below normal Friday and Saturday with highs ranging from the upper 20s to mid 30s. Not quite as cold Sunday with highs moderating into the mid and upper 30s. Lows will be quite cold with the upper single digits and teens Friday night then with surface high pressure settling overhead Saturday, lows mainly in the single digits above zero with a few spots likely dipping below zero. .LONG TERM...(Sunday night through Thursday) Issued at 331 PM EST Thu Mar 4 2021 High impact weather potential: None is expected. Zonal to upper level ridging for the first half of the week leads to unseasonably mild conditions. Low pressure likely tracking by to our northwest will then increase chances for rain heading toward midweek. Not as mild to end the period. Highs are expected to be well into the 40s to the low 50s Monday then mainly the 50s Tuesday and Wednesday when a few spots could even hit the 60 degree mark. Highs Thursday in the upper 30s and 40s. Lows in the mid 20s to low 30s Monday and Wednesday nights and the 30s to low 40s Tuesday night. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 639 PM EST Thu Mar 4 2021 VFR conditions expected this evening before ceilings lower overnight into Friday morning. MVFR conditions will become widespread across much of the area. A few flurries or a light snowshower will be possible but not enough of a chance to warrant a mention in the TAF. VFR conditions will return by Friday afternoon. Light winds tonight. Winds increasing and becoming gusty from the northwest on Friday (G20kts). && .MARINE... Issued at 331 PM EST Thu Mar 4 2021 Increasing wind speeds will be the issue starting tonight as pressure gradient begins to ramp up again especially on the Lake Huron side. Small Craft Advisories have already been issued for the nearshore zones north of Sturgeon Point Light which is where the greatest probability of small craft conditions will occur through Friday. Will expand Lake Huron SC.A into the remaining zones starting Friday morning...and will probably need advisories for the Lake Michigan nearshore zones starting Friday afternoon. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...SMALL CRAFT ADVISORY from noon Friday to 5 AM EST Saturday for LHZ346-349. SMALL CRAFT ADVISORY until 5 AM EST Saturday for LHZ347-348. LM...NONE. LS...NONE. && $$ UPDATE...JK NEAR TERM...JPB SHORT TERM...AS LONG TERM...AS AVIATION...JK MARINE...JPB

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