textproduct: Cleveland

WHAT HAS CHANGED

The next round of wind headlines has been issued for Sunday afternoon through early Monday, for strong southerly wind gusts ahead of an approaching cold front. Southwesterly winds will remain gusty behind the cold front on Monday, and portions of the area may need a Wind Advisory to continue through the day Monday. Continued to refine snow chances and amounts Monday night into Tuesday, and increased accumulations slightly across portions of the snowbelt.

KEY MESSAGES

1) Southerly wind gusts ramp up Sunday afternoon through Sunday night, shifting southwest and remaining gusty behind a cold front on Monday. There is also a low potential for severe thunderstorms along the cold front late Sunday night into early Monday morning.

2) Wintry weather returns late Monday and Tuesday. Wind chills are expected to bottom out in the single digits Monday night into early Tuesday. Accumulating snow is likely in the primary snowbelt region Monday night into Tuesday, with scattered snow showers elsewhere.

3) Limited precipitation chances with a gradual warming trend expected for the second half of the upcoming work-week.

DISCUSSION

KEY MESSAGE #1: Two potent shortwaves will phase over the Plains on Sunday, allowing a full-latitude trough to deepen, take on a negative tilt, and quickly close off while swinging into the Great Lakes Sunday night into Monday. The upper-level evolution will guide a deepening surface low pressure from the central Plains into the northern Great Lakes Sunday night into Monday. Locally, a strong warm front will lift through ahead of the deepening low early Sunday, followed by a strong cold front late Sunday night or early Monday morning. The main local impact from this system will be another round of wind.

SYNOPTIC WIND GUST POTENTIAL:

A very strong (60-70kt+ at 850mb, 40-50kt+ at 925mb) southerly low- level jet will overspread the area quickly from the west Sunday afternoon and evening, remaining overhead Sunday night until the cold front moves through. It is always tricky to determine how much these very strong, warm advecting low-level jets will mix to the surface. Warm air advection is natural upglide, and the strongest jet moves overhead at night when mixing is also typically at a minimum. Still, will likely see a period of stronger gusty winds particularly west of the I-71 corridor Sunday afternoon and early evening as daytime heating supports a period of deeper mixing into the strengthening low-level jet. Wind gusts may back off at times after sunset, though as the low-level jet intensifies into Sunday night and the cold front approaches can't rule out occasionally stronger gusts continuing to make it down. The other area of concern is downsloping along the eastern lakeshore, particularly in Erie County, PA. Feel the potential for advisory-level gusts of over 40 knots or 46 MPH is high enough across our western CWA beginning Sunday afternoon, and in downsloping areas closer to the eastern lakeshore, to justify a Wind Advisory kicking in at 2 PM/18z Sunday. Given the magnitude of the low-level jet and greater downslope enhancement across Erie County, PA, went with a High Wind Watch for that county, where peak gusts in the downsloping Sunday night may exceed warning criteria of 50 knots or 58 MPH. Ran the advisory and watch through 12z/8 AM Monday across the board for now. Southeastern portions of our area generally do not see as much wind in these types of setups, so while the forecast calls for peak gusts into the 40 MPH range in our southeast Sunday evening and night, left them out of the advisory at the moment.

Winds shift southwesterly behind the cold front Monday morning, and will remain quite brisk through the day Monday and even into Monday night along the eastern lakeshore. Winds aloft behind the cold front will not be nearly as strong as ahead of it...generally in the 35-45kt range at 850mb and 30-40kt range at 925mb. Still, steepening low-level lapse rates behind the cold front, natural downglide in the cold advection, and a fairly tight pressure gradient and quick pressure rises through the day Monday will support much more efficient momentum transfer to the surface behind the cold front. The current forecast flirts with advisory-criteria gusts behind the cold front on Monday, especially across Northwest OH and near the lakeshore farther east, with a general 35-45 MPH forecast across most of the area and up to 50 MPH possible in some spots. Wind gusts will very gradually ease Monday night into Tuesday as deep low pressure gradually fills and exits.

Future headline considerations are...1) Whether we need a high- end advisory or warning for Erie County, PA for the downsloping winds Sunday night...2) Whether or not portions of the current wind headlines need extended through the day Monday...and 3) Whether or not southeastern portions of the area will need a Wind Advisory at any point during this event, with the main window of concern in that area being overnight Sunday night into pre-dawn Monday.

SEVERE WEATHER POTENTIAL:

A strongly-forced quasi-linear-convective-system (QLCS) will likely take shape to our west by Sunday evening along the approaching cold front. Instability across our area will be minimal to none, though very strong linear forcing with the front itself will attempt to maintain some form of forced, low-topped convective line east into our forecast area. A lack of a strong near-surface inversion and very robust wind fields aloft could allow more organized line segments to maintain a strong wind/low-end tornado risk into our forecast area late Sunday night into pre-dawn Monday. Overall confidence in the severe weather threat is on the lower end given the expected lack of instability and what should be a weakening trend in the convection across our area, though is worth keeping in mind. The SPC Day 2 Outlook does bring a Slight Risk (level 2/5) for damaging winds into the I-75 corridor, with a Marginal Risk (level 1/5) to just west of the Cleveland-Akron-Canton corridor. If dew points end up pushing into the mid 50s ahead of the front, it would increase the potential for minimal (up to 100 J/KG) SBCAPE to maintain through the night, which would increase confidence in severe potential. Meanwhile, dew points staying just slightly cooler in the upper 40s or lower 50s would increase confidence in convection weakening and severe potential diminishing across our local area. It is worth noting that given the very minimal amount of instability, any severe weather would likely occur in the absence of lightning.

PRECIP TIMING & AMOUNTS:

A developing band of moist isentropic lift ahead of the approaching warm front may bring a bit of light snow to our northern counties tonight, with little to no accumulation. Otherwise, mainly dry weather is expected through Sunday with a band of rain expected to accompany the front late Sunday night into early Monday. Overall QPF appears modest, in the 0.30-0.60" range across the area, which should keep any flooding concerns at bay.

KEY MESSAGE #2: A sizable chunk of mid-winter-like air will swing across the area Monday into Tuesday, bringing a brief return to much colder and in some areas snowy weather.

SNOW TIMING & POTENTIAL AMOUNTS: The back edge of the rain band with the cold front may briefly mix with snow before exiting to the east on Monday. Otherwise, generally moist cyclonic flow and steepening low-level lapse rates through the day on Monday should support disorganized flurries/snow showers through the afternoon. A sharp low to mid-level trough axis swings across the area late Monday afternoon into Monday night, which along with moisture from Lake Michigan will likely bring greater potential for scattered snow showers area-wide. By later Monday night and Tuesday, cold west to west-northwest flow will align over Lake Erie, allowing for a period of lake effect snow into the primary snowbelt region of Northeast Ohio and Northwest PA as some flurries/lighter snow showers linger across the rest of the area. Ridging builds later Tuesday into Tuesday night, which should cause general flurries/snow showers across the area to dissipate and cause lake effect in the primary snowbelt to significantly slow and eventually end.

Snow accumulations outside of the primary snowbelt will not be much, generally under an inch. There could be some slick spots outside of the snowbelt Monday night as temperatures drop well below freezing if any of the more general scattered snow showers are heavy enough to drop a light accumulation. In the snowbelt, guidance is suggesting a fairly brief window from overnight Monday night into Tuesday morning where well-aligned flow, moderate lake-inducied instability, fairly high equilibrium levels (near 10k feet) and respectably deep moisture depth to 8-10k feet should combine to allow for a short- lived window for fairly organized and efficient lake effect snow...particularly as wind fields slacken and allow for residence time and shoreline convergence to increase. Increased snow amounts a bit with this update in the favored west flow locales, particularly the higher terrain slightly inland from the lakeshore. Do feel that an advisory may eventually be needed for the core snowbelt.

TEMPERATURES AND WIND CHILLS: While not especially hazardous, as we are now well into mid-March and have some 70+ degree weather under our belt the colder temperatures the first half of this week will be quite jarring. Expect quickly falling temperatures on Monday through the day, with wind chills quickly falling into the 10s late Monday afternoon/evening. Lows will range from the mid 10s to lower 20s Monday night/early Tuesday, with highs on Tuesday stuck in the 20s. Parts of the area will likely dip into the 10s one more time Tuesday night. In terms of wind chills, the coldest values will be overnight Monday night into Tuesday morning, bottoming out in the single digits above 0.

KEY MESSAGE #3: A gradual warming trend is expected to begin on Wednesday, with more seasonable to perhaps somewhat milder than average temperatures likely by Friday and Saturday. A generally benign weather pattern is expected Wednesday through Saturday, with minor precipitation chances Wednesday into Wednesday night and again Friday night into Saturday.

AVIATION /06Z Sunday THROUGH Thursday/

Main concern with this TAF issuance is another round of strong, gusty winds. A strong warm front will lift across the area this morning. In its wake, an impressive 50-70 knot low-level jet will overspread the area from the west through the day today. Initially colder surface temperatures early this morning may keep these winds elevated above the surface for a few hours, so low-level wind shear is possible early this morning, but expect temperatures to warm enough by 10-12Z for gusts to start reaching the surface. For this reason, left low-level wind shear out of the TAFs. S to SE winds should averaging 10-15 knots with gusts of 20-30 knots by mid morning, increasing to 20-25 knots with gusts of 30-45 knots this afternoon. Loss of daytime heating late this evening and early tonight should allow the gusts to relax somewhat, but still expect winds to remain gusty through the end of the TAF cycle.

Otherwise, VFR is expected through the period until a line of showers moves west to east across the region ahead of a strong cold front late tonight.

Outlook...Non-VFR likely to return in showers and storms late tonight. Non-VFR will likely linger in scattered rain showers changing to snow showers on Monday with lake effect snow possible Monday night into Tuesday across the Snowbelt.

MARINE

Active marine conditions return today as winds increase ahead of a potent low pressure system lifting out of the central Plains. Winds will quickly turn SSE behind a warm front this morning and increase to 15-25 knots, so Small Craft Advisories kick in at 15Z and run through tonight as SSE winds further increase to 20-30 knots. These are warm advective winds over a cold lake surface, so that will prevent gale force winds from mixing down until the trailing cold front crosses Lake Erie Monday morning. Behind the cold front, winds will turn WSW and increase to 30-40 knots Monday. Will keep the Gale Watch for Monday and Monday night with this morning's forecast package since it is 3 periods out, but Gale force winds are a slam dunk in the cold air advection Monday and Monday night.

W winds will gradually diminish to 15-20 knots Tuesday then turn S at 10-20 knots by Wednesday and Wednesday night ahead of a weak front and associated trough crossing the southern Great Lakes. High pressure attempting to build in behind this feature should lead to light and variable winds Thursday.

CLE WATCHES/WARNINGS/ADVISORIES

OH...Wind Advisory from 2 PM this afternoon to 8 AM EDT Monday for OHZ003-006>014-017>020-027>031-036-037-047-089. PA...Wind Advisory from 2 PM this afternoon to 8 AM EDT Monday for PAZ003. High Wind Watch from this afternoon through Monday morning for PAZ001-002. MARINE...Small Craft Advisory from 11 AM this morning to 8 AM EDT Monday for LEZ142>149. Gale Watch from Monday morning through Tuesday morning for LEZ142>149-162>169.