Area Forecast Discussion
Issued by NWS Paducah, KY
Issued by NWS Paducah, KY
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984 FXUS63 KPAH 050801 AFDPAH Area Forecast Discussion National Weather Service Paducah KY 301 AM CDT Sun May 5 2024 .KEY MESSAGES... - An unsettled weather pattern will see scattered showers and storms starting this new week increase in coverage and intensity potential by mid week. - Breezy south winds will pick up in similar fashion, offering 30-35 mph gust potential Tuesday-Wednesday. - A warm and relatively muggy air mass holds through mid week before a cool off with lower humidity returns spring like temperatures and dew points as we finish out the week and head into next weekend. && .DISCUSSION... Issued at 300 AM CDT Sun May 5 2024 Saturday convection looks like it was amplified during the approximately 22-03z time frame by peak diurnal destabilization along with a weak/subtle wave that presented some (15-20 units) channelled vorticity advecting across portions of SEMO/SIL. There was also a distinct but weaker (about 15 units) vort that helped the convection fire east of the Lakes in the southern Pennyrile. Shear was minimal, generally AOB 20 kts, as were overall 700-500 MB lapse rates, at 5-6 C/KM, so these vorticity maximas combined with the diurnal destabilization in the warm/soupy air mass of low-mid 80s highs and mid 60s dew points helped drive that (mostly) sub severe convection. The environment presented today is less on all accounts thru about 21Z. After that, we start to see the presentation of the open wave from the southern Plains begin to work its channelled vorticity into SEMO from the Arkansan Ozarks. The NBM picks up on this with likely-categorical pops spreading across the area thru the evening and overnight as the low center tracks into south-central MO by 12Z Monday. The air mass won`t be quite as juiced as yesterday, but low-mid 60s dew points should still help convective fueling coincident with the H8 LLJ cranking upwards to near 40 kts by Monday morning. The new day 1 outlooks general with marginal risk svr staying just to our south. With better lapse rates and shear still lacking, we can`t argue that, so we anticipate more of a heavy rain impact but cannot altogther rule out the possibility of an isolated stronger cell or potential thereof. The wave weakens upon its track into/across the PAH FA Monday, which maintains high pops for us but overall impacts lessen. Six hour QPF of 1/2-3/4" overnight transitions to 1/4-1/3" during the day. The clouds/pops will hold Monday highs in the 70s over all but the far southwest, where some late day clearing helps bump highs up to around 80 there. Teleconnected ridging is still signalled in the models and looks to offer a relative pause with respect to pops heading into Monday night. However, late Monday night into Tuesday morning, we do see the models start to advect a well defined first lobe of vorticity incoming from the next big storm system into/across the FA. This will begin to uptick pops late Monday night in our west as lapse rates start to inch above 6C and bulk shear responds in kind with a similar increase as the nose of the upper jet begins to swing into play. Likely to categorical pops should then spread west-to-east across the FA Tuesday as these features migrate thru, but the bulk moisture is slightly displaced ahead of their arrival. Still, we like the broad painting of slight risk severe for Tuesday, given the bulk shear and lapse rate increases. Another relative pause may occur Tuesday night, despite still mid chance (west) to low likely (east) pops prevailing, as that aforementioned convective episode shifts further east. Dew points draw down into the lower 60s, maybe even upper 50s in our far north, by early Wednesday morning, and embedded flow waves/energy are displaced outside the bounds of the FA. This pause is relative and short-lived, however, as the parent storm is poised to move in Wednesday. Bulk shear takes off and lapse rates balloon ahead of the arrival of its energy, Wednesday afternoon-evening. It spawns surface cyclogenesis upon its approach that warm sectors us with dew points again rising to near 70F with max temps rising into the mid 80s. We`d expect strong-severe storms to grow from Wednesday afternoon-evening into Wednesday night as the surface cyclone tracks from MO-IL- IN by Thursday morning. All modes severe along with heavy rain potential look to be in the offerings, so SPC/WPC both respond in kind with a broad painting of SLGT for our entire FA. In addition to all of that, gradient winds pick up gusts with 30-35 mph potential both Tuesday-Wednesday. Pops linger Thursday into Friday, but the air mass metamorphosis is ongoing and completes. Temps and dew points draw down markedly, from Wednesday highs in the low-mid 80s to upper 60s and lower 70s by Friday. Dew points move from upper 60s/near 70 Wednesday, into the 50s Thursday and 40s Friday, offering a refreshing break from the summer-like humidity that prevails over the first half of the week. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 300 AM CDT Sun May 5 2024 Nightime microphysics curve of IR satellite imagery indicates a spread of IFR-low MVFR bases ongoing across KMVN at this writing. There may be some similar drops in VSBYS to MVFR at times, but most modeling sticks with the MVFR base presentation. These are expected to become prevalant at all terminals with time, and prevail into the day, lifting into low VFR this afternoon. While an isolated shower/storm cannot be ruled out, most pcpn looks to hold off til the planning phase of the forecast and beyond as an open waved low pressure system lifts across the Ozarks. It will offer the chance for further flight restrictions upon its lift over the area tonight. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$