Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/02/21

Area Forecast Discussion
National Weather Service New Orleans LA
925 PM CST Mon Mar 1 2021 .EVENING UPDATE... Performed a forecast update this evening to reflect obs/radar trends as well as short-range guidance through Tuesday afternoon. The cold front that passed through the area is on its way well south into far outer marine zones this evening, with gusty northeasterly winds prevailing and remaining especially strong across marine areas where Small Craft Advisories are currently in effect through 9AM. Just some lingering post-frontal stratiform showers and drizzle lie in its wake with chilly overnight temperatures. Main focus shifts back to the west as a surface low pressure area continues to develop along the front, roughly 100mi SE of Galveston, TX, with an 850MB low tilted just to the northwest across coastal Texas. As this surface to 850mb low approaches from the west, winds in the low levels will steadily increase owing to intensifying WAA/isentropic upglide above the shallow post-frontal airmass in place. CAM`s illustrate this process well with showers increasing in coverage around or just before 06Z for western areas, particularly south of I-10/12 with coverage spreading north and east through early Tuesday. As this 850MB low tracks across just north of the CWA into south-central MS, so will the region of maximized omega/vertical ascent in the low-levels right above the frontal inversion per HRRR soundings for midday Tuesday. Given this, NBM thunder probabilities did come up enough to propose a few thunderstorms, as elevated parcels lifted from around 800-825mb indicates enough instability to produce cloud to cloud lightning in the lower to mid troposphere. This is very reasonable going through short-range guidance tonight and will let the mention of showers and thunderstorms ride through the day on Tuesday. Otherwise, the surface low looks to track just along or south of the SE LA coastline during the day. Depending on the exact location of the low and how far north the warm sector pulls into our far outer Marine zones will depend if any stronger surface- based storms develop. But this threat will be confined to right at the low and to the south and east into the warm sector. Good news is this system will be fast to depart late Tuesday, with most rain coming to an end around sunset with gusty northerly winds building in behind the system. Expect Small Craft Advisory conditions for marine zones to come during this time frame in subsequent updates. KLG && PREV DISCUSSION... /issued 422 PM CST Mon Mar 1 2021/ SHORT TERM (Tonight through Thursday)... A potent shortwave trough will move east across the southern plains and Arklatex region tonight and Tuesday morning. A west to east oriented cold front has pushed through most of the forecast area today, and this boundary will continue pushing south into the north Gulf coastal waters tonight. Isentropic lift north of the boundary will result in areas of rain and possibly a few thunderstorms from time to time in southern areas tonight. The shortwave trough will continue to move east across the lower Mississippi valley Tuesday afternoon and evening with the associated surface low moving east along the old frontal boundary that will drifting north just off the southeast Louisiana coast. Widespread rain showers and a chance of thunderstorms will accompany this system, however once again severe thunderstorm appear unlikely due to cooler low level temperatures and fairly weak mid level lapse rates. Rainfall amounts should be decent, but not excessive with average amounts expected to range from .75 to 1.5 inches. Drier and cooler conditions will prevail with the sun returning on Wednesday as high pressure builds in behind the front and low pressure area. The surface high will continue to build in on Thursday with a modifying airmass allowing high temperatures to push back up near normal in the mid to upper 60s. LONG TERM (Friday through Monday)... The next potent shortwave trough will move southeast through the central Gulf coast region late Friday, Friday night and early Saturday morning. The models continue to depict moderate to locally heavy precipitation amounts with this system mainly late Friday and Friday night, however once again severe thunderstorms look unlikely. Most of the weekend should see surface high pressure in control and dry and mild weather if this system continues to time out like the models currently indicate. AVIATION... 00Z TAF FORECAST... Widespread low CIG`s and drizzle/light showers continue generally across all of SE LA and southern MS this evening, with gusty NE surface winds following a recent frontal passage. Expect these conditions to persist overnight, with flight CAT`s ranging from VFR to periods of MVFR through before midnight, to more widespread MVFR after midnight to around daybreak as CIG`s continue to descend. Showers will increase in coverage roughly 10-12Z from the SW, as a low pressure center approaches the area. Look for more persistent widespread moderate to heavy rain throughout the day on Tuesday, reducing flight CAT`s due to low VIS/CIG`s. All rain is expected to depart to the east late Tuesday afternoon and evening, with low clouds continuing through the evening. KLG MARINE... A cold front will continue to push south into the northern Gulf and stall out tonight. Cold air advection behind the front and high pressure building in from the north will result in northeast winds picking up to 15 to around 20 knots through tonight. Have issued Small Craft Advisories for portions of the eastern coastal waters and sounds late this evening through mid morning on Tuesday. "Exercise Caution" headlines are in effect in most remaining waters tonight. A low pressure system is forecast to form along the front and then pass through the waters on Tuesday. Offshore flow will return behind the front as high pressure builds in from the northwest on Tuesday night through Thursday. A renewed period of near or exceeding Small Craft Advisory criteria winds is likely to need additional headlines Tuesday night. Showers and thunderstorms will be most numerous through Tuesday then drying out Wednesday and Thursday. Winds and waves will subside later on Wednesday through Thursday as high pressure builds into the region. Yet another low pressure system will move across the north Gulf late Friday and Friday night brining another period of moderate to stronger winds and increased wave heights. && .PRELIMINARY POINT TEMPS/POPS... MCB 47 52 38 60 / 90 100 10 0 BTR 52 57 41 61 / 90 90 0 0 ASD 53 60 41 61 / 80 100 20 0 MSY 56 62 45 60 / 80 90 10 0 GPT 53 60 43 60 / 60 100 30 0 PQL 50 60 43 60 / 50 100 40 0 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...Small Craft Advisory until 9 AM CST Tuesday for GMZ534-536-538- 550-552-555-557-570-572-575-577. MS...None. GM...Small Craft Advisory until 9 AM CST Tuesday for GMZ536-538-550- 552-555-557-570-572-575-577. && $$
Area Forecast Discussion
National Weather Service Melbourne FL
920 PM EST Mon Mar 1 2021 .UPDATE... Current...Surface cold front extends from Cross City to Gainesville and Saint Augustine early this evening, and continues to sag toward the northern CWA. To the south, diurnal CU/SC has dissipated across most of the area, however some low-mid level clouds have developed over the Space/Treasure Coasts as a result of interaction between the ECSB and Lake Okeechobee breeze. A few showers were noted on KMLB well offshore Volusia/Brevard Counties. Remainder of tonight...Latest run of the HRRR bring the front into the northern CWA by 04Z/11PM, which seems about an hour or so too quick, based on its current location/southward push. Nevertheless, the boundary will reach Volusia County around midnight then continue to ooze south into the central CWA, likely stalling across northern Osceola/southern Brevard Counties late tonight and then remaining stationary well into Tue afternoon. Low clouds are expected to sock in along/north of the front, with light rainfall breaking out as SW flow above the shallow (1km or so) NE-E flow in the post-frontal air mass. Made some minor tweaks to the early evening forecast, otherwise its basic premise looks solid. && .AVIATION...VFR expected to give way to MVFR CIGs from DAB-LEE south to ISM-MCO-MLB from 05Z-11Z as the cold front sags southward through the northern and central aerodromes. Should also see MVFR to local IFR VSBYs developing in light precip late tonight through Tue. VFR expected for the VRB-SUA corridor. && .MARINE...Cold front and associated northerly wind surge will sag south to between the 41009/TRDF1 and SIPF1 by sunrise Tue. Current CWF already accounts for this, with winds shifting to N-NNE whilst increasing to 15-20kt, which should push seas over the Volusia 20- 60nm leg. && Cristaldi/Fehling && .PREV DISCUSSION... (Issued 348 PM EST Mon Mar 1 2021) Tue... A cold front extending from the NE US to the Gulf Coast will push to the south tonight. The ridge across south FL will then be displaced and the front will reach the Cape latitude Tue, and will stay there for the rest of the day. PWAT values will remain in the same range through the period, around 1.4 inches up north and 1.15 inches down south. Rainfall activity is expected to start tonight as the late east coast sea breeze collides with the west and northwest wind flow producing showers along the coast and bringing them to the Atlantic waters. As the front reaches the Cape and Orange County Tue morning, light showers will linger across east central FL expanding in coverage in the afternoon towards the northern counties north of Orange and Brevard counties. This is a generally an idea of location and timing for showers as the front moves south, lingers then starts to lift north. Max temperatures will range from the lower 70s in northern Volusia County to the lower 80s from Orlando-Cape Canaveral southward. Tue night-Thursday...Ridging aloft centered over the Caribbean begins to erode late Tuesday and into Wednesday with the approach of an upper disturbance tracking across the southern MS Valley towards the coastal Carolinas through midweek. Locally, central FL will be positioned in the warm sector behind a warm front lifting over north FL early Wednesday. This will keep lingering shower mentions in the forecast overnight and during the pre-dawn hours especially along the coast as onshore winds veer rapidly southwest ahead of the system. At the surface, models are in very close agreement with a closed low developing in the Gulf prior to daybreak Wednesday, moving onshore over the FL Big Bend and quickly exiting the area off the North FL/South GA coast by sunrise. Even though a bulk of available moisture will ride just north of the forecast area, PW increase to over 1.50" and thus rain chances rise to 50-60% through midday, mainly north of Orlando and Cape Canaveral. Adequate forcing from the upper disturbance will support thunder on Wednesday, lasting into the afternoon as a trailing cold front passes through the area. A few storms could be strong during the day, with frequent lightning and gusty winds the main concerns. Southwest to west winds will veer northerly by dusk, with showers coming to a close as the stronger cold front passes through. Thursday will be much different, with drier air and building high pressure over MS leading to no mentionable rain chances and noticeably cooler and pleasant temps. Temperatures Wednesday morning drop to the mid to upper 60s, with afternoon highs greatly influenced by the position of the cold front and cloud cover. Temps only reaching the mid to upper 70s north of Orlando, but will soar to the mid 80s for the Treasure Coast and Lake O vicinity. A rapid decline is expected after sunset Wednesday, with lows bottoming out in the 50s Thursday morning, with seasonal values in the 70s by Thursday afternoon. Long term...(Modified previous discussion) High pressure initially North of the Grt Lakes will extend a period of drier cooler air across much of the SE states at the end of the work week. North component winds will keep temperatures pleasantly cool with highs in the 70s and lows in the 50s. The forecast becomes more challenged late Fri into Sat as another fast-moving plains disturbance crosses into the north gulf region early Sat. Early depictions from operational EC and GFS both show a notable increase in local rain chcs during Sat, along with a chance of storms as an energetic, deepening gulf system is shown with an early degree of consensus crossing the state during the upcoming weekend. Have increased the PoPs on Sat a bit to go with the guidance shift. Slightly cooler and drier for the rest of the weekend with highs in the low-70s or upper- 60s and lows in the 50s or low-60s. && .AVIATION... VFR this afternoon with SW/W winds. Then isolated VCSH possible mainly for the northern and coastal terminals this evening. After midnight, low cigs (MVFR) were included and these will linger through at least Tue morning with winds veering from the NW/N/NE from KISM northward and variable from KMLB to KSUA. Brief shower activity will expand for the rest of the terminals on Tue. && .MARINE... Tonight-Tue...A cold front will approach the local Atlantic waters late tonight and linger across the Cape on Tue. Winds will increase mainly for the waters east of Volusia and a Small Craft Advisory has been issued for Tue morning. Then seas will build and the advisory will expand for the nearshore Volusia and offshore Brevard waters on Tue afternoon with seas of 6-8 ft and winds 18-21 kt. Wednesday-Friday...Approaching upper disturbance and surface low pressure will cross just north of the local waters early Wednesday, with a strong cold front passage expected later in the day. Onshore winds 15-20 knots (near 20 knots offshore Volusia) will veer southwest by midday Wed, shifting northerly through the evening. Hazardous seas of 5-6 ft nearshore and up to 8 ft offshore for zones north of Sebastian Inlet, with a Small Craft Advisory in effect through early Wednesday afternoon. Behind the cold front, seas will improve slightly, becoming 4-6 ft and winds reducing to 15 knots. && .CLIMATE... List of low temperatures observed (Low Obs) this morning and the warm low and high record temperatures for today, March 1. Low Warm Low High Obs Records Records Daytona Beach 70 66 2017 86 2018 Leesburg 71 69 2018 87 2017 Sanford 71 71 2007 88 2012 Orlando 68 68 1913 90 1918 Melbourne 70 71 2007 89 2018 Vero Beach 70 74 1997 88 2018 Ft. Pierce 67 71 2007 89 1913 && .PRELIMINARY POINT TEMPS/POPS... DAB 64 72 64 77 / 20 50 40 60 MCO 66 80 65 79 / 20 40 20 50 MLB 67 80 66 82 / 20 40 20 50 VRB 67 82 65 85 / 20 30 20 30 LEE 65 76 66 77 / 20 40 20 50 SFB 66 77 65 79 / 20 50 20 60 ORL 68 79 67 80 / 20 40 20 50 FPR 66 83 65 85 / 20 30 20 30 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...Small Craft Advisory from 1 PM to 7 PM EST Tuesday for Flagler Beach to Volusia-Brevard County Line 0-20 nm. Small Craft Advisory from 1 PM Tuesday to 1 PM EST Wednesday for Volusia-Brevard County Line to Sebastian Inlet 20-60 nm. Small Craft Advisory from 7 AM Tuesday to 1 PM EST Wednesday for Flagler Beach to Volusia-Brevard County Line 20-60 nm. && $$