Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/06/22

National Weather Service Albany NY
916 PM EST Mon Dec 5 2022 .SYNOPSIS... Clouds will thicken and lower overnight ahead of a warm front. The warm front will bring periods of mainly rain tomorrow morning through the afternoon with above normal temperatures into the mid week. The unsettled weather continues on Wednesday ahead of a cold front before cooler more seasonable temperatures return late in the week. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Zone of clear sky from the eastern Catskills through the mid Hudson Valley and near the Capital Region to the Berkshires and NW CT is shifting east as more widespread high clouds are spilling east to cover the entire region. The entire region will be cloudy by midnight, but just high and thin clouds as the deeper cloud cover spreads over our region more toward daybreak. The high clouds should limit the radiational cooling in areas that have calm winds but until the clouds do spread, temperatures will drop a degree or two before holding steady between midnight and daybreak. Some temperatures have fallen below the forecast, so some adjustments to temperatures and sky cover through daybreak were made. Steady south winds in many areas but some protected areas are calm to near calm. There will be big differences in temperatures in small distances depending on where it is calm and where the steady south winds persist, also the clearing versus the thicker cloud cover. PREVIOUS DISCUSSION: High pressure /1035 hPa/ continues to shift east/northeast of Nova Scotia late this afternoon into tonight. The mid and upper level flow continues to shift southwesterly ahead of the northern stream trough over the northern Plains and central Canada. The southern stream remains over the southern Plains and Southeast. Split mid and upper level flow dominates across the CONUS currently, and once again it looks like the forecast area will get into a warm sector tomorrow ahead of the next cold front with above normal temps. Cirrus clouds continue to increase in the warm advection pattern. Some thinning in the clouds is likely early tonight with some decoupling. Sfc dewpoints remain in the teens and 20s in the dry low-level air mass. Temps may drop off prior to midnight into the 20s to lower 30s, but then steady or slightly rise in the early morning hours. In the initial surge of warm advection it will take some time for the column to saturate with the dry low-level air mass. Clouds will thicken and lower with some lower stratus possible along and east of the western New England higher terrain. Some could reach locations south and east of the Capital Region prior to daybreak. Most of the guidance including some of the CAMs such as the 3-km HRRR have very little pcpn prior to daybreak. The one exception is with the return low-level southeasterly flow from the low onshore may allow for some spotty light snow mixed with rain depending on how warm the sfc layer gets across the eastern slopes of the southern Greens and Adirondacks. We have some slight to low chance PoPs in these areas in the early to mid morning hours. Lows tonight will range from the upper 20s to lower 30s over the higher terrain and sheltered valleys with lower to mid 30s in the valley areas. Again, temps may steady or slightly rise with the south/southeast breeze picking up. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/... Tomorrow...A warm front approaches from the south and west in the morning with the southwesterly low-level jet at 850 hPa increasing to 35-45 kts. The moisture advection increases with PWATs increasing to 1 to 2 STDEVs above normal based on the latest NAEFS. Some shadowing is possible again in the Greater Capital Region, portions of the eastern Catskills and Schoharie Valley. The best isentropic lift on the 285/290K surfaces occurs in the mid to late afternoon. We continued to increase PoPs to categorical values across the entire region by then. We should see a gradual increase from the southwest to northeast during the late morning into the afternoon. A light wet snow/sleet to rain transition may occur in the west/southwest Adirondacks before transitioning to all rain. Any accumulation would be light amounting to a light coating to a couple tenths. In the low-level warm advection pattern, we increased temps closer to the ECM MOS and NBM with highs in the upper 40s to lower 40s in the valleys areas or below 1500 feet in elevation. We went with upper 30s to mid 40s over the higher terrain above 1500 feet. A south to southeast breeze will increase 10-15 mph or so and pick up overnight. Tue night...A very mild December night is expected with periods of light rain continuing, as the warm front lifts north and east of the region. A lull in the precipitation is possible overnight, as the warm front and associated weak short-wave move across the region. The southeast to south winds may increase to 10-20 mph with some gusts 25-35 mph along the western New England higher terrain and confluent area of the Capital Region. PWATs increase to +2 to +3 STDEVs above normal. H850 temps rise +1 to +2 STDEVs above normal based on the NAEFS. The lowest temps may occur in the early evening, as temps may steady or slightly rise overnight. Lows will be in the mid 40s to around 50F in many valley locations, and upper 30s to lower/mid 40s in the higher terrain. Min temps will likely be 15-20 degrees above normal. Some patchy fog may form in a few spots. Total rainfall prior to daybreak Wed will range from a third of an inch to three quarters of an inch in the valley areas with the favored southwest flow orographic enhancement areas of the southwest Adirondacks, southeast Catskills, and southern Greens ranging from 0.75" to 1.50" with some locally higher amounts. Some hydro issues are expected with only within bank rises. Wednesday...The cold front to the system moves across the region during the late afternoon with continued showers. The synoptic forcing does not look particularly strong. The latest ECMWF has a weak wave form along the front moving across PA and southern NY. The latest NAM has some pockets of elevated instability with Showalter stability indices of 0 to -2C. A rumble of thunder is possible, but lack of appreciable CAPE and heating will be an issue with lots of clouds that should inhibit any strong thunderstorms at this time. SPC has general thunder across most of the region. Max temps were favored close to the ECM MOS and NBM with highs well above normal in the mid 40s to around 50F over the higher terrain and lower to mid 50s in the valleys with spotty upper 50s possible in the mid Hudson Vally/NW CT. Additional rainfall will be fairly light with two tenths of an inch to a third of an inch (unless convection forms). Wednesday Night...Cold advection occurs in the wake of the front and possible wave moving east of Cape Cod. Some west/northwest flow upslope rain showers and perhaps a rain/snow shower mix occurs for the western Adirondacks, southern Green and northern Taconics. Little or no snow accumulation is expected overnight with perhaps a coating in a few spots. Lows fall into the upper 20s to lower/mid 30s north and west of the Capital Region, and expect upper 30s to lower 40s to the south and east. && .LONG TERM /THURSDAY THROUGH MONDAY/... Upper system exits through eastern Canada Thursday and as upper confluence increases over eastern Canada, strengthening low level ridging will build south out of Canada. Cold advection will be weak at first, but then, by Thursday night and Friday the colder air will build into our region. Highs Thursday with increasing sunshine in the 40s to lower 50s with around 40 higher terrain. Friday through Monday, there are major disagreements in the overall upper pattern in sources of guidance/ensembles. Some sets of guidance/ensembles suggest a complex evolution of an upper system and low level forcing contributing to chances of rain and snow showers Friday into the weekend. Other sets of guidance/ensembles show a weakening upper impulse tracking well south of our region while flat northern stream upper ridging continues over our region through much of the weekend with little to no precipitation. The mean of the ensembles suggest more clouds than sun and just slight chances for rain and snow showers with the snow showers mainly at night Friday night. Sunday could be mainly dry but again more clouds than sun as a potentially more organized upper impulse or developing closed low could begin an approach to our region later Sunday into Monday. By Monday afternoon, there could be some chances for isolated rain and snow showers. Highs Friday around 40 to mid 40s with mid 30s to around 40 higher terrain. Highs Saturday in the upper 30s to lower 40s with lower to mid 30s higher terrain. Highs Sunday and Monday in the upper 30s to lower 40s with mid 30s higher terrain. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... Through 00Z Wed...High clouds will thicken and lower through the night as moisture steadily increases. There is potential for a lower cloud deck (MVFR/IFR) to advect into the region off the ocean as southeasterly winds increase. Went with a SCT mention at KPOU/KPSF later tonight to hint at this potential. Otherwise, dry air at midlevels will delay top-down moistening such that any vsby restrictions due to rain hold off until after 18Z. MVFR cigs may develop a few hours earlier, however. Expect conditions to deteriorate to borderline MVFR/IFR with both cigs and vsby from 18Z to the end of the TAF period as showers become more widespread. Winds will be light and variable overnight, except south- southeasterly at 5 to 10 kt at KALB. Winds will be mainly out of the south to southeast on Tuesday at 5 to 10 kt. Borderline low-level wind shear conditions will develop after 06Z at KGFL and after 12Z at KPOU/KPSF. LLWS was omitted from KALB due to the expectation of slightly stronger surface winds. Outlook... Tuesday Night: High Operational Impact. Breezy. Definite RA. Wednesday: High Operational Impact. Definite SHRA...RA. Wednesday Night: Low Operational Impact. Slight Chance of SHRA. Thursday: No Operational Impact. NO SIG WX. Thursday Night: No Operational Impact. NO SIG WX. Friday: No Operational Impact. NO SIG WX. Friday Night: Low Operational Impact. Slight Chance of SHSN. Saturday: Low Operational Impact. Slight Chance of SHRA...SHSN. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...Wasula NEAR TERM...NAS/Wasula SHORT TERM...Wasula LONG TERM...NAS AVIATION...Thompson
Area Forecast Discussion
National Weather Service Des Moines IA
932 PM CST Mon Dec 5 2022 .UPDATE... Issued at 932 PM CST Mon Dec 5 2022 Another night, another southward shift in the precipitation area. 0z model data including the HRRR, NAM, and RAP (21z) have all shown a 30 to maybe 60 mile southward shift in the chance of precipitation. I emphasize `chance` as cross sections and soundings continue to indicate a fairly dry sub-cloud layer, which as earlier discussion noted would result in only light snow or flurries. This may enter our west central counties between 3 and 6am before the focus of precipitation shifts closer to I-80 around 8 or 9am. With the shift southward, sprinkles/light rain cannot be ruled out farther to the southeast in our forecast area. Any snow accumulation will be a dusting at most. Comparing the upcoming event to this morning`s event, this event does not have the fgen band that helped to focus the wintry precipitation corridor, but rather broad low level thermal lift. Further, last night`s 0z HREF had a sub-county stripe of wintry precipitation for this Monday morning. Tonight`s 0z HREF run has no (mean) QPF over the state. Will continue to monitor trends and adjust the forecast overnight as additional data becomes available. && .DISCUSSION.../Tonight through Monday/ Issued at 217 PM CST Mon Dec 5 2022 Key messaging highlights: * Light snow/flurries possible north Tue * Appreciable precip anticipated Thu/Thu Night, with winter travel impacts likely, but precip types still uncertain * Seasonal temperatures continue Our pattern will remain active through the period with token snow chances initially tomorrow, a more significant system Thursday into Thursday night, and then another potential system early next week. At onset this afternoon, all the precipitation from earlier today has ended but mid and high clouds continue to stream through the MO Valley driven through the base of the polar trough and Pacific stream. This will stay in place into tomorrow with a weak upper wave ejecting out of the confluence of the two streams from the northern Rockies and Midwest. Model trends have diminished precip potential from 00z, but a few continue to suggest a swath of light snow or flurries north. There isn`t a whole lot to hang your hat on as a forcing mechanism other than theta-e advection increasing across the persistent baroclinic zone, but will keep at least a token mention in the forecast. A system will track trough the base of the polar trough Wed, with fairly deep thermodynamic and kinematic forcing, but limited lower level moisture will keep any precip and impacts to our north. Most of our attention should be turned toward the Thu/Thu night system however, which will track through CA into early Wed before ejecting through the central Plains. Deep, phased kinematic and thermodynamic forcing will arrive through the day Thu blossoming precipitation across central and southern Iowa later in the day. There is medium to high confidence in this regard, but confidence in how this plays out is much less with Iowa in the thermal transition zone, both surface and aloft. The GFS/GEFS suite seems to be the warmest solution, with mainly rain and only light snow north, but much of the remainder guidance is on the cooler side and more aggressive with at least several inches of snow farther south. These solutions also include various degrees of separation between the front/surface features, and dry slot aloft, so while rain or snow seem to be the dominate precipitation types driven by near surface wet bulbs, differences with the melting/warm layer aloft and meridional dry slot placement also leave graupel or freezing drizzle in play for brief periods. Some weak convection can`t be ruled out along the northern fringe of where ever the dry slot ends up either. Thus our initial messaging will be more of the `heads up` variety with appreciable QPF rather than trying to pin down any specifics. The current forecast has precip ending Friday morning, although if current trends hold it may extent through the morning commute and beyond, with the start of the weekend looking dry. PoPs do return late in the weekend into early next week however, with wintry mix chances, but confidence is quite low at this point. How the western CONUS trough evolves is still very much uncertain with little model agreement and a wide range of solutions. && .AVIATION.../For the 00Z TAFS through 00Z Tuesday evening/ Issued at 529 PM CST Mon Dec 5 2022 Mid and high level clouds will continue to pass over Iowa in the wake of a cold front that has moved south of the state. Winds from the north will become from the northeast and east by daybreak Tuesday. While there is high confidence in VFR conditions through the period, bases below FL100 will be possible several hours either side of midday Tuesday. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Ansorge DISCUSSION...Small AVIATION...Ansorge
Area Forecast Discussion
National Weather Service Lincoln IL
740 PM CST Mon Dec 5 2022 .SYNOPSIS... Issued at 740 PM CST Mon Dec 5 2022 A fair amount of clouds to prevail the rest of the week across central and southeast Illinois, along with periodic chances of rain. Areas of fog will likely develop overnight and lift Tuesday morning, mainly impacting areas near and south of I-72, and some of the fog may be locally dense. Light rain chances will spread northeast over central and especially southeast Illinois Tuesday afternoon into Tuesday evening, with dry weather expected Wednesday. More widespread rains will occur Thursday into Friday morning. Temperatures will be near or slightly above early December normals, with highs in the 40s or 50s this week. && .UPDATE... Issued at 740 PM CST Mon Dec 5 2022 Low clouds starting to become more prevalent south of I-70 and also scraping areas near I-74, with some light drizzle being reported there. High-res models have been showing a band of light rain or drizzle forming over northern Illinois later this evening and mainly staying to our north, but close enough to warrant some low PoP`s across the far northern CWA. Across the southeast CWA, rain chances have been trimmed back some, but will keep a mention of drizzle overnight as the lower clouds expand along with some fog. Hit the fog a little harder in recent updates as CAM`s have been persistent with this over the southern half of the forecast area, and NBM 4.1 probabilities are around 25% chances of visibility below a mile. Some minor temperature updates have also been made, primarily nudging them up a degree or two. && .SHORT TERM...(This evening through Tuesday) ISSUED AT 300 PM CST Mon Dec 5 2022 A weak southerly flow is gradually increasing low level moisture into central and southeast IL this afternoon and stratus cloud decks 1.5-3k ft cover much of the area. Though a large hole in the low clouds is from Scott county sw into northeast MO where temps warmed into the low to mid 50s. Temps over CWA were in the low to mid 40s, mildest from Springfield sw. Radar mosaic is not showing much over central/se IL at mid afternoon with light showers and drizzle more over KY and moderate to heavier rains from southern half of TN south. 21Z surface map shows 1002 mb low pressure over the OK panhandle while a weak cold front was over se parts of WI/IA into nw MO. Weakening southerly winds to veer NE later this evening and overnight as low pressure moves into the Ozarks by Tue morning. Strengthening inversion to trap more low level moisture with CAMs showing more fog develop later this evening and overnight from Lincoln southeast with locally dense fog possible. Fog that develops to diminish during mid/late Tue morning. Lows tonight range from around 30F nw of the IL river, to the upper 30s to near 40F in southeast IL. Weak low pressure to lift up into the lower Ohio river valley early Tue evening and spread light rain chances northward into central and especially southeast IL during Tue afternoon and evening where around a tenth inch of rain expected. Isolated thunderstorms should stay se of Lawrence county late Tue afternoon into Tue evening closer to frontal boundary near the Ohio river. Highs Tue in the mid to upper 40s in central IL, but range from lower 40s by Galesburg to lower 50s south of I-70. && .LONG TERM...(Tuesday night through Monday) ISSUED AT 315 PM CST Mon Dec 5 2022 Weak lift to push east of central IL during overnight Tue night with light rain chances diminishing. CAMs shows patchy fog just south of CWA Tue night and for now keeping mention of fog out of southeast counties though could be a little fog with low clouds and light rain. Lows Tue night in the lower 30s nw of the IL river and 40-45F in southeast IL. Brief break rain chances during Wed and Wed evening with rain chances focused along frontal boundary from OK/AR eastward into KY/TN. Could be some breaks in the low clouds over northern CWA Wed while central and especially southern parts stay more in the low clouds on Wed. Highs Wed range from upper 40s northern CWA to 50-55F in southeast IL. A stronger storm system to eject ne from OK Thu and near central IL by noon Friday. Models have trended slower with this storm system and brunt of rains to arrive Thu into Fri morning and diminishing during Fri afternoon. Pops may need to be increased for Friday with cutoff upper level lows tending to be slower to move through as a 548 dm 500 mb low is along the northern IN/OH border by 6 pm Fri with cyclonic flow still over central IL. Rainfall amounts of a half to three quarter inch look likely over area Thu into Fri morning while isolated thunderstorms have shifted further southeast of CWA over KY and far se MO Thu afternoon into Thu night. Also the rain/snow mix is along and north of I-88 in northern IL and areas northward Thu afternoon into Fri morning. Highs Thu similar to Wed with 45-50F northern CWA and 50-55F southern CWA. Weak upper level ridge moves over IL on Saturday with dry weather expected Fri night into Saturday evening with highs around 40F northern CWA and 40-45F southern CWA/se IL. Extended models differ with how they handle wx system in an active wx pattern going into early next week. Sunday does not look as wet with just 20% pops of mainly light rain. A better chance of precipitation arriving next Monday as another deep upper level trof digs over the Rockies and likely ejecting another low pressure system ne from the central/southern high plains toward the Midwest. Looks warm enough for mainly rain chances with highs in the 40s next Monday. CPC 6-10 Day outlook for Dec 11-15 has 55-65% chance of above normal precipitation over central IL while 40-50% chance of above normal temperatures. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 520 PM CST Mon Dec 5 2022 Widespread ceilings around 2000 feet early this evening, though some higher ceilings above 3000 feet are likely to impact KPIA for a time this evening. HRRR guidance suggests this higher surge stopping before reaching KSPI/KBMI. After that, a large part of central Illinois will see ceilings fall well below 1000 feet overnight. High-res model guidance has been fairly steady with an area of potentially dense fog over the southern half of Illinois overnight into Tuesday morning, though at the moment looks to be just south of the terminals. However, NBM probabilities of visibility below a mile are around 25% at KSPI overnight and early Tuesday morning, so something to keep an eye on through the evening. While visibility reductions are likely to improve toward mid morning or so, clouds will be slower to ascend, with ceilings likely staying IFR or low MVFR through the end of the period. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Geelhart SYNOPSIS...07/Geelhart SHORT TERM...07 LONG TERM...07 AVIATION...Geelhart
Area Forecast Discussion
National Weather Service Jacksonville FL
852 PM EST Mon Dec 5 2022 ...AREAS OF DENSE FOG TONIGHT... .UPDATE... Issued at 852 PM EST Mon Dec 5 2022 A diffuse frontal is across the area and so difficult to place but appears to be near or just south of Flagler county and then oriented west to northwest into the FL panhandle and into southwest GA. This front will slowly work northward through Tuesday. The JAX 00Z sounding, HREF, and HRRR all suggest radiation fog formation tonight but the extent of it is a bit unclear. At this time, the chances of a widespread dense fog event seem a bit lower than last night. Nonetheless, the best chances look to be over our western zones and perhaps a relatively small area from JAX northward along the I-95 corridor and toward U.S. highway 1. We can`t rule out another dense fog advisory for parts of the area, mainly inland areas from about Alachua county northward into interior southeast GA. For the update, there was little change to the areas of dense fog advertised. Patchy fog was included for the evening hours in the Suwannee Valley area where Live Oak has reported fog. The POPs on average are less than 15 percent but there are a few sprinkles possible inland zones tonight. Min temps again from upper 50s to 60, with lower 60s possible where any mid level clouds hang around. For the marine forecast, little change was needed in the CWF with generally light and variable winds tonight and seas of 3-5 ft, with dominant period near 10 seconds. && .NEAR TERM... Issued at 251 PM EST Mon Dec 5 2022 A weak pressure pattern will be in place through tonight with a broad low level ridge across FL, a weak warm front across south GA and a coastal trough offshore of the local Atlantic coast. Diurnal heating across NE FL enabled a weak west coast sea breeze to form with a few very light spotty showers drifting inland across our Suwannee River Valley zones. A few weak returns and enhanced cumulus were also noted near the St. Johns River basin where some light sprinkles will be possible through early evening. The best shot of measurable rainfall will focus near the Altamaha River basin through tonight north of the lifting warm front, but rain chances will be less than 20%. The main weather impact tonight (and the next several nights) will be late night fog. There is plenty of low level moisture in place across the area and as the boundary layer cools and decouples, fog and low stratus will once again develop through sunrise Tuesday. High resolution guidance indicated the highest probabilities of dense fog (visibility < 1/4 SM) along and west of the I-10 corridor from JAX to Live Oak, and near I-75 from VAD to GNV. Mild temps wild range above climo in mid 50s to low 60s. && .SHORT TERM... (Tuesday through Wednesday night) Issued at 251 PM EST Mon Dec 5 2022 Warm days and foggy nights are expected as high pressure builds over the area, both at the surface and aloft with an anonymously strong 500 mb ridge of 590-592 dam amplifying across the GOMEX this period. Temps will generally range 6-12 deg above climo values with highs in the upper 70s to low 80s inland with sea breezes keeping the coast slightly cooler in the mid 70s. Lows at night will range in the upper 50s to low 60s. && .LONG TERM... (Thursday through next Monday) Issued at 251 PM EST Mon Dec 5 2022 Overall a continued dry pattern and above normal temperatures. A weakening front with meager moisture moves across the region late Friday into Saturday mainly brining passing clouds and not much rain chance (< 10% across SE GA). A slight cool down into Saturday as the front begins to stall across the FL peninsula but temps will still generally range above normal into early next week. The latest ECMWF is much faster with the approach of the next frontal system compared to the GFS Sun-Mon, with the official forecast displaying the NBM composite with a low chance of showers Sun night into Mon. && .AVIATION... (00Z TAFS) Issued at 702 PM EST Mon Dec 5 2022 Currently, TAFs remain at VFR with areas of ceilings around 5 kft with a few sprinkles possible. A diffuse warm front lifting slowly north from northeast FL area and plenty of low level moisture and boundary layer coupling/decoupling will allow areas of fog and low ceilings to develop tonight. Generally kept the current trend for inland TAFs going to LIFR and VLIFR after midnight, but show MVFR to possible brief LIFR for the coastal TAFs. Again, the highest chance of IFR or lower is expected to be at GNV and VQQ. The low vsby and celling restrictions should lift by about 14Z-15Z, with VFR ceilings returning. Again, some patches of MVFR still possible 15Z-18Z. Sfc winds will be going toward calm tonight, and then variable Tue 13Z-17Z, shifting to the east for coastal TAFs in the aftn due to sea breeze. && .MARINE... Issued at 251 PM EST Mon Dec 5 2022 A weak warm front will lift northward across south Georgia tonight with fog potential impacting inlets after midnight. Light and variable winds are expected Tuesday through Thursday as high pressure builds over the local waters. A cold front will approach the waters from the north late Friday and moves south of the waters through Saturday as high pressure builds north of the region. Seas may near advisory levels with the front Friday into Saturday over the outer waters. Rip Current Risk: Moderate rip current risk through Tuesday. && .PRELIMINARY POINT TEMPS/POPS... AMG 59 77 58 80 / 10 10 0 0 SSI 60 74 60 75 / 10 0 0 0 JAX 58 77 58 78 / 10 0 0 0 SGJ 60 74 60 75 / 0 0 0 0 GNV 58 79 58 81 / 10 0 0 0 OCF 60 80 59 81 / 10 0 0 0 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$

.SYNOPSIS... Issued at 324 PM CST Mon Dec 5 2022 Key Messages: -Snow is possible Thursday and again next Monday. Although distant in time, it`s worth noting the systems Thursday and Monday are the result of the deep Hudson bay upper level low retreating north toward the North Pole. This pattern shift appears to be opening the door for Pacific storm systems to track through or near the Central Plains. && .SHORT TERM...(This evening through Tuesday night) Issued at 324 PM CST Mon Dec 5 2022 Radar has been indicating midlevel frontogenesis across wrn and ncntl Nebraska all day. The RAP model shows this feature getting stronger tonight and is the basis for a chance of snow showers. The latest POP forecast uses the blend of GFS, NAM, SREF and ECM but shifts the POP about 20 miles south to line up with the frontogenesis as indicated by radar and satellite. QPF is very light, less than 0.05 inches, and this is likely the result of dry air below 700mb. The temperature forecast tonight leans on the short term model blend plus bias correction. Widespread cloud cover tonight should hold up radiational cooling and this forecast is warmer than the NBM 50th percentile. The NBM 50th percentile was very close to the RAP model for highs Tuesday. The RAP model is the basis for lows around 10 north to 20 south Tuesday night. A warm front should move east tonight and Tuesday morning followed by a weak back door cold front Tuesday afternoon. The front will drift into the Sandhills Tuesday evening and lift slowly north after midnight. .LONG TERM...(Wednesday through Monday) Issued at 324 PM CST Mon Dec 5 2022 The models continue to converge on a system closing off across the cntl Plains Thursday. The NAM, GFS and ECM are closing off an h700mb low across nrn KS/Neb and this should be sufficient to product light snow across parts of wrn and nctrl Neb. There has been little change in the ECM QPF amounts and the GFS and ECM ensemble means suggest 1 to 3 inches of snow also. Higher QPF amounts are expected across ern Nebraska. The system is currently along the nrn CA coast and predicted to move south through srn CA/NV and then east northeast through WY and into Nebraska. Another snow chance is in place next Monday. Once again, the ECM/ECM ensemble are leading the way suggesting a disturbance off the coast of Japan will move east and be in the Gulf of AK Friday. The system will then move southeast through the nrn Rockies and close off across ern Colo Monday. Although distant in time, it`s worth noting the systems Thursday and Monday are the result of the deep Hudson bay upper level low retreating north toward the North Pole. This pattern shift appears to be opening the door for Pacific storm systems to track through or near the Central Plains. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 525 PM CST Mon Dec 5 2022 VFR conditions are expected to primarily prevail through tomorrow evening. The exception will be in scattered -SN overnight, where localized MVFR visibility would be possible. The most likely area for this to occur is across the southern Panhandle into the central Sandhills. -SN exits the area through sunrise tomorrow morning, with clearing skies expected after. Winds shift from north to south overnight, then back to west and northwest by tomorrow evening, generally below 15kts. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CDC SHORT TERM...CDC LONG TERM...CDC AVIATION...Brown
Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
926 PM EST Mon Dec 5 2022 ...New UPDATE... .UPDATE... Issued at 919 PM EST Mon Dec 5 2022 The main changes to the forecast this evening will be to the PoP/Wx grids, based on current radar and satellite trends. Upstream across Middle TN, we are seeing much lighter and more scattered precip, with much warmer cloud tops on IR imagery. So we should see less precip coverge in most of the area after midnight. The CAMS show some resurgence of showers developing over our area, which is certainly possible, but the main QG forcing will have exited to the east around 06Z. The forecast update will cut back on PoPs, as well as remove the slight chance of thunderstorms tonight and tomorrow morning. No lightning strikes have been observed anywhere near East TN this evening, and with the exit of the main QG forcing and warmer cloud tops, it is very unlikely to occur. && .SHORT TERM... (This evening through Tuesday) Issued at 312 PM EST Mon Dec 5 2022 Key Messages: 1: Rain showers will continue to move across the area tonight through tomorrow, with a slight chance for a few rumbles of thunder. 2. Low probability of localized flooding across portions of the southern TN valley and southwest NC. If flooding issues arises, it will likely be across low lying and flood prone areas. Discussion: A good slug of precipitation is currently moving across the southern TN valley and southwest NC this afternoon. The HRRR and RAP both show this first wave of moderate precip slowly sliding to our east later this evening. However, additional showers will develop and spread in from southwest to northeast through the night as isentropic lift persists ahead of a warm front to our southwest. Additional QPF overnight ranges from 0.5 to 0.75 inches across the southern TN valley and southwest NC, around 0.5 inches across the central and northern TN valley, and 0.25 inches across northeast TN and southwest VA. If we see any minor flooding issues it will be across the southern areas as mentioned above. Also, low-end, elevated, instability is seen in soundings overnight so will include slight chance for thunder. There is some uncertainty on how POPs play out through the day tomorrow. We remain in a moist environment with elevated PWATS but precip will be determined on where the lift is focused, which will be determined by where the front sets up. The NAM suggests that the higher POPs shift north through the day tomorrow and into KY, leaving much of TN valley on the drier side with only slight chance/chance POPs in place. This idea is currently supported by the NBM as well. This means that after good coverage of morning showers we should start to see more spotty showers during the afternoon hours with much less coverage. Highest POPs for tomorrow will be focused along the TN/KY/VA state lines, where better lift is expected. Temperatures remain well above normal through the period due to the southwest flow and abundant cloud cover. && .LONG TERM... (Tuesday night through next Monday) Issued at 312 PM EST Mon Dec 5 2022 Key Messages: 1. Periods of rain will continue through the week. Some flooding concerns still present for areas that see repeated rounds of moderate to heavy rainfall. Best chance for this is generally north of I-40 mid to late week. 2. Above normal temperatures Wednesday and Thursday will gradually cool into the weekend. Discussion: Tuesday night through most of the rest of the work week will continue to be cloudy, rainy, and pretty warm. Quasi-stationary boundary will remain laid out in the southern Ohio Valley and sometimes dipping into the Tennessee Valley. Continuous moisture will be fed into the region as the low level flow generally remains out of the south/southwest. Models continue the trend of keeping the boundary and axis of heaviest precipitation Tuesday night into Friday to our west and north, along West/Middle TN up into southern KY. This is still close to the eastern Tennessee valley, and therefore we`ll still likely see waves of rain throughout the week, but am still expecting QPF amounts to be the highest further west and north. For the middle of the week, areas north of Interstate 40, and the Cumberland Plateau will likely see the highest rainfall totals. Have continued to keep QPF amounts close to NBM/WPC guidance with a slight bump up in totals in areas north of Interstate 40, and a slight decrease in southeast TN into southwest NC. Forecasted amounts generally remain 2-3" for the week with mostly light rain expected, and periods of more moderate rain at times. Model discrepancies crop back up as we move into Friday with regards on how to handle the low moving into the Great Lakes region and finally forcing through the front, and drying out the area. Will continue with PoP chances lingering into Friday afternoon, but as we get closer to the end of the week, hopefully we`ll be able to trim back the temporal extent of the PoPs when models come into better agreement on timing. We`ll take a break from rain heading into the weekend before another front that is forecasted to quickly sweep through the eastern U.S. during the first part of next week. This system should help to usher in a period of colder weather to start of next week. && .AVIATION... (00Z TAFS) Issued at 614 PM EST Mon Dec 5 2022 Highly variable conditions are expected at the TAF sites as rain spreads across the area tonight and tomorrow. Conditions have been varying from VFR to IFR across the TN Valley, depending on where the heavier rain occurs. CHA is expected to have the best chance of IFR vis and cigs tonight as rain will be heavier there, with TYS expected to have predominantly MVFR conditions with periods of cigs dropping to IFR. At TRI, downslope winds off the mountains have kept cigs VFR, but this should drop to MVFR when rain increases there tomorrow morning. MVFR cigs will likely persist through tomorrow, with IFR cigs possible. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 48 64 59 70 / 100 70 60 60 Knoxville McGhee Tyson Airport, TN 42 64 58 69 / 100 80 70 80 Oak Ridge, TN 43 61 56 67 / 100 80 80 80 Tri Cities Airport, TN 47 62 54 66 / 90 80 70 80 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM...DGS LONG TERM....ABM AVIATION...DGS
Area Forecast Discussion
National Weather Service San Diego CA
130 PM PST Mon Dec 5 2022 .SYNOPSIS... Partly cloudy cool weather will prevail the rest of this afternoon. A colder system will bring light showers late tonight through Tuesday night. Gusty westerly winds will occur at times through Tuesday night in the mountains and deserts. Fair and dry but continued cool weather will follow later Wednesday through Saturday. Another system could bring more precipitation Saturday night and Sunday. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Partly cloudy conditions prevailed early this afternoon with a mix of stratocumulus and cirrus. Temperatures were mostly in the upper 50s and lower 60s west of the mountains. Broad troughing covers the western US with the main upper low just west of Eureka. That upper low will move southeast to the Mojave Desert by Tue night. RH values of mostly 90+ percent will extend from near the surface to around 500 MB according to NAM and local WRF late Tuesday afternoon, though dynamics will be modest including little or no surface front. Some instability will occur with local CAPE values over 200 J/kg late Tuesday/Tuesday night. GEFS/ENS Ensemble members show mostly 1/10 inch or less near the coast and mostly less than 1/4 inch near the coastal mountain slopes, but given the convective banding that the HRRR and our local WRF are indicating, there could be local amounts over 1/4 inch, and the 1.3 km resolution Cansac WRF shows some amounts around 1/2 inch in the San Diego County Mountains. Hourly rainfall rates look mostly slim in the high-resolution models, possibly up to 0.25 inch but mostly less, so the risk of flooding or debris flow is minimal. Since this will be a cold system, with 850 MB temperatures around 2 deg C, the snow levels could fall to around 5000 feet MSL, especially Tue night when nocturnal cooling and the coldest profile will occur. Thus, a few locations in the mountains could get 1-3 inches of snow, mainly above about 6000 feet. We will continue with long-wave troughing over the West Coast after the upper low passes to the east Wednesday due to a strong upper trough off the Pac NW/British Columbia coast. A wave will deepen the long wave trough this weekend and could bring some mostly light precipitation Saturday night and/or Sunday. Enough ensemble members and even WPC QPF indicate some measurable precip, so we will add at least a slight chance of rain Sunday. Due to the long wave troughing, don`t expect any warm weather anytime soon with daytime highs 5-10 deg F below seasonal averages through early next week. Nighttime lows will not be as far below average, and so far, NBM 10th percentile temperatures show the risk of valley frost to be low late this week. && .AVIATION... 052120Z...SCT-BKN clouds 1500-2500 ft MSL through 03Z Tue. Low clouds increasing in coverage again aft 03Z Tue. Periods of BKN cigs with VIS 1-3SM during showers between 06Z and 15Z Tue. Coastal slopes and higher terrain will be obscured through Tue. Mtns and Deserts...W-NW winds gusting 25-35 kt locally 45 kt through today. MOD up/downdrafts and LLWS expected over/east of mtns. && .MARINE... There is a slight chance of light showers tonight through Wednesday morning. Otherwise, no hazardous marine conditions are expected through Friday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ PUBLIC...Maxwell AVIATION/MARINE...PG
Area Forecast Discussion
National Weather Service Tucson AZ
141 PM MST Mon Dec 5 2022 .SYNOPSIS...Patchy fog in the morning and drier conditions for Tuesday. Another passing weather system on Wednesday will bring a chance of showers to areas northeast of Tucson and cooler temperatures areawide. Then dry conditions are expected into the weekend with gradually moderating temperatures. && .DISCUSSION...20z Visible satellite shows the last remnants of the low stratus clouds and fog burning off in the valleys of Southeastern Arizona. The fog took a little longer to burn off as many locations observed 1/4 mile of visibility, or in some cases a car length away. The sun has been trying to burn all of the fog and the low stratus to dry out the area, but there was a lot of cloud cover. So, the delay in the burned off has the potential for another round of fog for Tuesday morning. Plus, with a good radiation inversion developing during the night and the very light winds, we can expect patchy fog for a few hours on Tuesday morning. HREF and HRRR model runs shows patchy fog developing in valleys with very isolated areas of dense fog such as near riverbeds or bodies of water. Overall, the fog will not be as severe as it was this morning due to dew point depression being near 3 points instead of it was this morning. By 9am Tuesday, any fog or low stratus will be burned off to pave the way for a drier and sunny day with moderate daytime temperatures. By Wednesday, a storm system will drop into region to bring some showers mainly north and east of Tucson and cooler temperatures areawide. The ensemble models are not enthusiastic for showers in Tucson, but it could change if the shortwave trough deepens in the next 24 hours. As for now, the favorite area is still north and east of Tucson. Thursday and through the weekend, the synoptic pattern becomes a zonal and allowing us to dry out. Ensembles are hinting at another storm system to come into the region by Monday with another tease of showers. The ECMWF ENS model is optimistic on the precipitation side while the GEFS is leans a little dry, aka a sprinkle for Tucson for ten minutes. && .AVIATION...Valid through 07/00Z. FEW-SCT lower level clouds 2-5k ft AGL will continue thru 06/02z and slowly becoming SKC till the end of the forecast period. Patchy fog can develop after 06/06z mainly in valleys, including KOLS, KDUG, and KTUS. By 06/16z the fog should start to lift and burned off to clear skies. Expect westerly winds less than 8 kts through 06/04z and becoming variable less than 5 kts until 06/18z and returning to westerly flow at 8-12kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Patchy morning fog can be expected in valleys tomorrow and clearing by mid-morning. Mostly dry conditions expected for the rest of Tuesday as dewpoints gradually drop. A passing weather system on Wednesday will bring a threat of showers to areas north and east of Tucson along with cooler temperatures. Dry conditions are then expected into the coming weekend before another weather system passes by late Sunday/Monday bringing a threat of showers. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Visit us on Facebook...Twitter...YouTube...and at