Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/12/20

Area Forecast Discussion
National Weather Service Charleston SC
1030 PM EST Fri Dec 11 2020 .SYNOPSIS... High pressure will prevail through late Saturday. A cold front will then move through the region Monday with a coastal low pressure system to likely impact the area mid week. Cooler and drier high pressure should then return starting Wednesday night. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... As of 1025 PM: Based on latest observations and HRRR run, I will update the forecast to add a mention of patchy fog along the lower SC coast. Otherwise, no change needed to the forecast. As of 840 PM: Recent IR satellite images indicated that cirrus cloud cover was increasing across the forecast area this evening. The combination of persistent cloud cover and warming llvl thicknesses should keep temperatures generally steady, cooling by only 1-2 degrees through the rest of the night. Given the limited cooling, dewpoint depressions should remain between 1 to 2 degrees. The forecast update will feature less mention of patchy fog across the region, retained the mention of fog along the lower Altamaha River. As of 6 PM: Based on satellite trends, I expect that cirrus will increase across the forecast area through the night. The forecast update will feature slight changes to hourly sky and temperature forecasts. Previous Forecast: High pressure will prevail as a coastal trough lingers across the area tonight. The rest of the afternoon will remain rain free with plenty of sunshine. Overnight, upper-level moisture will return from the west and there will be an increase in cirrus clouds across the area. While some models hint at some light showers offshore, significant dry air (PWATs ~0.5-0.8 inches) should limit any measurable rainfall. Therefore, have left out any mentionable POPs. With less radiational cooling tonight, lows will be in the mid to upper 40s inland and low to mid 50s along the coast. There could be another round of fog tonight, even though ingredients seem less favorable than the previous night/morning. Even so, winds are expected to become calm in most places and the condensation pressure deficits will be favorable for fog formation. Therefore, due to persistence and some hints in the models, have added patchy fog to the forecast. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... High confidence that high pressure will bring mostly dry and unseasonable warm weather through the weekend with a cold front to move through Monday. Although there will be a few showers around starting Saturday night due to a bit better moisture and upper forcing, the best rain chances/amounts will come Monday when a more potent storm system impacts the area. Instability will be limited but can`t rule out a few weaker storms. Rain amounts should generally be about a quarter of an inch or less, although could be a bit higher, especially northern and western areas near the Pee Dee/Midlands/CSRA. It will also be breezy on Monday. Temperatures will remain above normal through the period, likely peaking Sunday afternoon with more clouds and rain holding temperatures down on Monday. Should see temperatures more steady or even rising Sunday night due to the increasing low-level warm advection. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... A cold front will move offshore Monday night, leading to drier weather and colder temperatures. A weak coastal trough is expected to form on Tuesday, bringing some showers to the immediate coast. Though, inland areas will remain dry. Some showers are possible everywhere on Wednesday as a weak front moves through. High pressure will yield dry conditions and cold temperatures on Thursday. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... Flight conditions across the terminals is forecast to remain generally VFR through the 0Z TAF period. A period of ground fog is possible at both KSAV and KCHS during the predawn hours. Otherwise, expecting SCT to BKN cirrus with calm winds tonight and steady SW winds during the daylight hours on Saturday. Extended Aviation Outlook: Moderate to high confidence this period at KCHS/KSAV. Some restrictions are possible starting late Saturday night and then moreso Sunday night into Monday as a storm system impacts the area. Breezy conditions and a few weak storms are possible Monday, mainly through mid afternoon before a cold front moves through. Additional restrictions are then possible Tuesday and Wednesday as a coastal storm system impacts the area. && .MARINE... Rest of today and tonight: As a coastal trough lingers over the area, high pressure will prevail overnight. A southerly flow will persist with winds 5-10 kt. Seas will be 1-2 ft. Saturday through Wednesday: Moderate to high confidence through the period with high pressure expected to prevail until a cold front moves through Monday and a coastal storm likely impacts the area mid week. Wind/sea conditions are expected to stay below Small Craft Advisory levels through Sunday night before Small Craft Advisories are then likely needed Monday into at least Tuesday. There is a small chance that a marginal Gale Warning will even be needed Monday, mainly for the offshore GA waters and Charleston County nearshore waters. && .TIDES/COASTAL FLOODING... High astronomical tides due to the lunar perigee and new moon could yield minor coastal inundation as early as Sunday morning along the southern SC coast. More significant inundation is possible starting Tuesday when winds will be more favorable, maybe even extending southward along the GA coast. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...NED SHORT TERM... LONG TERM...MS AVIATION...NED MARINE...BSH TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Lincoln IL
854 PM CST Fri Dec 11 2020 .SYNOPSIS... Issued at 528 PM CST Fri Dec 11 2020 A rainy night is in store across central and southeast Illinois...with overnight low temperatures ranging from the upper 30s in the Illinois River Valley to the upper 40s near the Indiana border. The rain will gradually come to an end by Saturday afternoon. && .UPDATE... Issued at 854 PM CST Fri Dec 11 2020 0230z/830pm surface analysis shows a 1006mb low over northeast Missouri with a warm front extending into central Illinois. Based on latest wind fields, it appears the front stretches from just south of Danville to north of Rantoul. S/SE winds and temps in the middle 50s prevail south of the boundary, while NE winds and much cooler readings in the lower to middle 40s are noted north of the front. Rain has overspread all of central and southeast Illinois, with hourly rates of one tenth to one quarter of an inch observed on MRMS data. The rain will continue for the balance of the evening into the first part of the overnight before gradually tapering off toward dawn across the S/SW KILX CWA. 00z NAM and HRRR both indicate a faster departure of the rain on Saturday, which seems reasonable given drying trend on upstream radar across central/western Missouri. Have updated PoPs Saturday to reflect the rain ending everywhere except across the Illinois River Valley by noon. Further west, a trailing deformation zone will keep chance PoPs in the forecast through the remainder of Saturday afternoon along/west of the Illinois River. && .SHORT TERM...(This evening through Saturday) ISSUED AT 302 PM CST Fri Dec 11 2020 Radar data showed continued rain development over MO and moving northeast into Illinois. Moisture channel imagery showed the shortwave in western KS with diffluence in the upper level flow over the mid MS valley area. Surface analysis shows low center over west central MO which is progged to move east northeast over central IL tonight. Models have sped up the movement of the short wave and the surface low, so that it moves quicker over IL tonight and so the lift and period of lift is shorter with the result being lower pcpn amounts. Amounts have dropped to 1/2 to 1 inch now with some locally higher amounts. 850mb moisture transport displayed in the SPC mesoscale page still shows good advection from MO into IL. Precip water amounts still around 1 inch. Pcpn moving out by Saturday afternoon but with only weak low level northerly flow over the area. .LONG TERM...(Saturday night through Friday) ISSUED AT 302 PM CST Fri Dec 11 2020 Next shortwave approaching region late Sunday into Monday, but goes by mainly to the south of the area as seen in the progs. Then another minor wave goes by mainly over southern IL on Tuesday night. Pattern then is benign through rest of week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 540 PM CST Fri Dec 11 2020 Light rain continues to spread northeastward across central Illinois late this afternoon: however, ceilings have been slow to lower. 23z/5pm obs show a large pocket of VFR ceilings persisting east of the Illinois River...with only KPIA down to IFR. Radar trends suggest the heavier rain upstream across Missouri/southwest Illinois will eventually saturate the airmass from the top-down, resulting in lowering ceilings as the evening progresses. Based on latest obs and HRRR forecast, have introduced IFR ceilings at KSPI/KDEC after 02z...then further northeast to KCMI after 09z. Predominant rain will come to an end from south to north across the area by late Saturday morning into the afternoon...with ceilings rising to MVFR at KCMI by around 15z and further west to KSPI by 17z. Further west/northwest, IFR will linger through the remainder of the 00z TAF period at both KPIA and KBMI. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Barnes SYNOPSIS...Barnes SHORT TERM...Goetsch LONG TERM...Goetsch AVIATION...Barnes
Area Forecast Discussion
National Weather Service Tallahassee FL
917 PM EST Fri Dec 11 2020 .UPDATE... Previous forecast appears to be on track. Patchy fog will be possible overnight but shouldn`t be as dense or widespread as last night. && .PREV DISCUSSION [625 PM EST]... .NEAR TERM [Through Saturday]... Surface high will push east into the Atlantic overnight as the next upper wave and associated cold front approach. This will help keep winds and thus temperatures up for most of the area along with much less in the way of fog. The exception will be in the eastern Big Bend and southern GA where there will be a better chance for decoupling leading to areas of fog and cooler temps than the rest of the region. Increasing moisture off the Gulf could bring isolated late night showers to the western Panhandle per latest HRRR and 12Z deterministic guidance. Front will continue to slowly approach our SE AL counties late Saturday but most if not all of the showers associated with the front should hold off until Saturday Night. Saturday will be very mild with most locations away from the coast well into the 70s for highs. Low shower PoPs carried only in the far west. .SHORT TERM [Saturday Night Through Sunday Night]... An upper level shortwave trough moving northeast from Missouri into Illinois on Saturday with the associated surface low centered over Michigan. These systems to our north will keep precip chances for our region at a minimum. There will be a weak ridge above us on Sunday, keeping temperatures relatively warm in the low to mid 70s across the region with lows remaining in the upper 50s low 60s by Sunday night. .LONG TERM [Monday Through Friday]... A second upper level shortwave trough over the Pacific NW on Saturday is expected to dive south towards north central Texas by Sunday. Cyclonegenesis at the surface is expected to develop in eastern Texas by Sunday night and move east along with the shortwave trough aloft. At this time, global models maintain a weakly unstable environment across our region ahead of the cold front passage with the low pressure system. Showers can develop across the area by Monday but, the nature as to how widespread the activity will be is uncertain. The forecast details will become more apparent in the coming days. After the passage of the cold front, temperatures will range from the mid 40s for lows to the 60s for highs. By Tuesday, another shortwave trough will quickly move through the southern US; but with little recovery time from Monday, there will likely not be enough moisture for this system to produce measurable precipitation. This front will however, introduce a reinforcement of cold air with highs reaching the upper 50s. Lows will be seasonal with the much of the region falling to the low 40s. .AVIATION... [Through 00Z Sunday] Mostly VFR conditions are expected through the period. Some fog may be possible overnight, but not expecting it to be as dense as this morning. .MARINE... Favorable boating conditions are expected to continue through today, with Cautionary conditions are expected to start Friday night ahead of a cold front. By Sunday, Winds are expected to drop into more favorable boating conditions briefly before once again increasing to cautionary conditions on Monday ahead of the next system. Swells through this time are not expected to increase much beyond 1-2 feet, with swells occasionally reaching 3 feet through the weekend. .FIRE WEATHER... Hazardous fire weather conditions are not expected over the next several days. .HYDROLOGY... With widespread rainfall totals of less than an inch expected over the next week, there are currently no significant flooding concerns at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not requested. However, spotters are always encouraged to safely report significant weather conditions when they occur (while following all local, state, and CDC guidelines) by calling the office or tweeting us @NWSTallahassee. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 49 73 56 74 59 / 10 0 10 10 30 Panama City 59 73 61 73 59 / 10 10 10 10 30 Dothan 52 72 56 72 55 / 10 20 20 20 50 Albany 48 73 56 73 57 / 10 0 10 10 40 Valdosta 45 73 55 75 58 / 10 0 10 10 20 Cross City 47 72 57 76 59 / 10 0 0 0 10 Apalachicola 59 72 60 72 61 / 10 0 10 10 20 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AL...None. GM...None. && $$ UPDATE...Merrifield NEAR TERM...Johnstone SHORT TERM...Montgomery LONG TERM...Montgomery AVIATION...Merrifield MARINE...Montgomery FIRE WEATHER...Johnstone HYDROLOGY...Montgomery