985 FXUS64 KHUN 040908 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 408 AM CDT Sat Jun 4 2022 ...New NEAR TERM, SHORT TERM, LONG TERM... .NEAR TERM... (Today) Issued at 408 AM CDT Sat Jun 4 2022 Light west-northwest winds aloft will persist across the TN Valley today, within the flow to the south of an elongated mid- level trough extending from eastern Manitoba into western Quebec. Clear skies, coupled with dewpoints in the mid 50s and light winds will allow temps to drop a few more degrees before sunrise, with some patchy ground possible in a few locations. Over the course of the day, we expect a gradual increase in cirroform clouds from the west as noted in recent IR satellite data. However, this should not have a significant impact on the diurnal warming curve, with highs expected to reach the l-m 80s. && .SHORT TERM... (Tonight through Monday night) Issued at 408 AM CDT Sat Jun 4 2022 Latest short term model guidance suggests that a weak mid-level vort max embedded within the prevailing west-northwest flow aloft will spread southeastward across southern MO overnight. Forecast soundings depict redevelopment of scattered mid-level clouds after Midnight as elevated warm advection strengthens downstream from this feature, and this should lead to slightly warmer overnight lows in the u50s-l60s. The disturbance is predicted to weaken considerably as it tracks southeastward across the Mid-South region and into the TN Valley on Sunday. Nonetheless, a few diurnally-driven showers and thunderstorms may develop along a low-level streamline confluence axis induced by the onset of southeasterly return flow across the Gulf coast states. We have kept POPs below mentionable levels due uncertainty in this scenario, but this does remain a possibility. On Sunday night, a slightly more defined mid-level shortwave is expected to shift east-southeastward from western KS/NE into the Mid-MS Valley, and should contribute to the development of showers and thunderstorms along a cold front in that region. It appears as if some of this convection may spread southeastward into the TN Valley (perhaps in the form of a small, loosely- organized MCS) late Monday afternoon/evening, as west- northwesterly gradient flow aloft strengthens in response to a building 500-mb anticyclone across northern Mexico and adjacent portions of south TX. Based on latest model consensus, we have indicated a gradual increase in POPs on Monday evening, with a slightly greater coverage anticipated across the northeastern corner of the forecast area. Although deep-layer shear will still be rather weak at this point, gusty outflow winds, frequent lightning and locally heavy rain will be possible with this activity. Temperatures will steadily increase throughout the short term period, with highs expected to reach the u80s-l90s by Monday afternoon, and lows predicted to rise into the m-u 60s by Tuesday morning. && .LONG TERM... (Tuesday through Friday) Issued at 408 AM CDT Sat Jun 4 2022 The west-northwest flow regime discussed above will remain a persistent feature across our region for much of next week, driven by an expanding subtropical ridge to our southwest and a positively-sheared trough extending across much of southern Canada. This will result in a active week of thunderstorm activity for the TN Valley, as we will remain in a seasonably warm/moist airmass to the south of a stalled frontal boundary to our northwest. Most of the global models suggest that another well- defined vort max and related MCS will spread east-southeastward across northern OK/southern KS and into the Ozarks on Tuesday night, perhaps providing a fairly widespread coverage of showers and thunderstorms as it reaches our forecast area on Wednesday. We have increased POPs into the 50-60% range to reflect both model consistency with this feature, and a slightly higher risk of storm organization and severe wind gusts, as deep-layer shear will increase into the 30-35 knot range by Wednesday. There are some indications that the stalled front may drift southward through portions of the region in the wake of this disturbance, perhaps providing a lower spatial coverage of convection on Thursday and Thursday evening. However, the front will likely lift northward once again on Friday morning, in advance of another well-defined mid-level wave and MCS that should be dropping southeastward from eastern portions of KS/OK and may approach our region Friday afternoon. && .AVIATION... (06Z TAFS) Issued at 1205 AM CDT Sat Jun 4 2022 VFR weather should prevail across the Tennessee Valley for the 06Z TAF period. Surface high pressure over the Ozarks will build to the Mid Atlantic/New England region on Sat. A NE flow rounding the high will continue across this region. Light winds overnight should increase into the 5-10kt range by the late morning with some higher gusts in the afternoon. Winds should subside somewhat towards the evening. Daytime heating should produce high based fair weather cumulus in the late morning and afternoon. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...70/DD SHORT TERM...70/DD LONG TERM...70/DD AVIATION...RSB