Subj : HVYRAIN: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Jun 02 2023 08:26:38 FOUS30 KWBC 020826 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 425 AM EDT Fri Jun 02 2023 Day 1 Valid 12Z Fri Jun 02 2023 - 12Z Sat Jun 03 2023 ....THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR NORTHWEST TEXAS AND PORTIONS OF EASTERN MONTANA... ....Southern Plains... No significant changes made to the previous outlook regions across the Southern High Plains. Another round of active convection likely across the Southern High Plains as the next area of mid to upper level height falls eject northeastward from northern Mexico into the Southern High Plains. Strong upper difluence moving into the Southern High Plains will support another round of organized convection pushing eastward late Friday afternoon into Friday evening from far eastern New Mexico into northwest Texas and western Oklahoma where an axis of MUCAPE values 2000-2500+ j/kg and PW values 1 to 2 standard deviations above the mean are expected. The latest simulated hi res radars suggest the developing convection squall line will be fairly progressive to the east. Still, HREF hourly rainfall probabilities are high for 1"+ amounts, 40-90% through the moderate risk area, dropping to 10-20% for 2"+ amounts. Given recent heavy rainfall amounts across this region, 400-600% of normal, additional runoff issues area likely as stream flows remain high as per the National Water Model.=20 ....Northern/Central Rockies and Northern High Plains... A fairly blocked mid to upper level pattern will persist day 1 from the Northern Rockies, eastward through the Northern Plains into the Upper Mississippi Valley and Great Lakes. Very slow moving mid to upper level troffing will persist on the western side of the blocking upper high forecast to remain in place from the Upper Mississippi Valley into the Great Lakes. This will support the potential for a well defined comma head deformation precip area to pivot from central to western Wyoming into central Montana where PW values are expected to remain anomalously high day 1, generally 2 to 2.5+ standard deviations above the mean. In this pivot area, HREF 24 hour probabilities are high for 1 and 2"+ amounts, with this potential additional rainfall falling across areas that have received 300-400% of normal precipitation over the past 2 weeks. The previous moderate risk area was extended approximately 100 miles to the south to cover the high 1 and 2"+ HREF neighborhood probabilities. ....Central and Southern Florida... No changes made to the marginal risk area across central to South Florida for the day 1 period. Latest forecast track of Tropical Depression #2 keeps the storm well to the west of the Florida peninsula as it drops south southeastward into the southeast Gulf of Mexico. Simulated radars from the latest hi res guidance show that any convection near the center will not directly impact Florida. Still, with a mid to upper level trof persisting over the eastern Gulf, and an axis of 1.75"+ PW values remaining across much of Florida, there will be the potential for locally heavy rains this afternoon across much of central to south Florida.=20 HREF neighborhood probabilities are high for 1, 2 and 3"+ amounts across central to South Florida, with even some 5"+ probabilities as high as 20%. Greatest concerns will be across the urban areas of southeast and southwest Florida for any runoff issues. ....Northern New York State and New England... A strong back door cold front is expected to push west southwestward across New England and northern New York State on Friday. An axis of anomalous PW values 1 to 1.5+ standard deviations above the mean and MUCAPE values of 500-1000+ j/kg expected along and ahead of this front. This will support potential for widespread scattered convection in an increasingly upper difluent pattern ahead of shortwave energy diving southeastward from eastern Canada into New England. HREF neighborhood probabilities are high for 1 and 2"+ amounts this period across large section of New England from western Maine, westward through much of New Hampshire, Vermont, Massachusetts, far northern Connecticut and northern New York State. Much of this region has seen below average precipitation over the past few weeks resulting in stream flows much below normal as per the National Water Model. Still, with potential for some isolated rainfall totals of 1-2" per hour, can not rule out some isolated runoff issues. Oravec Day 2 Valid 12Z Fri Jun 02 2023 - 12Z Sat Jun 03 2023 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS NORTHEAST NEW MEXICO INTO NORTHWEST TEXAS... ....Southern High Plains... The overall stagnant blocked mid to upper level pattern will persist into day 2 across much of the central to western U.S., comprised of a slowly retrograding closed upper high over the Upper Mississippi Valley into the Northern Plains and mean troffing from the Northern to Central Rockies into the Southern High Plains. Models are indicating another upper level difluence maxima sinking east southeastward late Saturday afternoon into evening from northeast New Mexico into northwest Texas. This area of shortwave energy/upper difluence will likely support another round of convection pushing east southeast in what will be a northward surge of instability across this region late Saturday afternoon. While model precip amounts are not as high as day 1, there will be potential for additional heavy rainfall amounts and potential overlap of day 1 amounts across a region that has seen much above average precip over the past few weeks. For these reasons, a small slight risk area was added for the day period over portions of northeast New Mexico into Northwest Texas. ....Southern to Central Plains into the Central to Northern Rockies... No significant changes made to the very broad marginal risk area across portions of the Southern to Central Plains, into the Central to Northern Rockies. An axis of above average PW values will continue across much of these regions between the mean troffing from the Rockies into the Southern Plains and the closed high over the Upper Mississippi Valley and Northern Plains. Model consensus for heavy amounts day 2 across much of the Southern and Central Plains is to the east of the day 1 axis. Given this and higher ffg values across the farther eastward locals in the Southern to Central Plains, the risk level was maintained as marginal. Across the Central to Northern Rockies, model consensus is for lesser qpf amounts day 2 than day 1. While there will be potential for locally heavy rainfall amounts, confidence is low with respect to placement, keeping the threat level across these areas at marginal. In addition, the CSU first guess fields continue to indicate only a broad marginal risk across these regions. Oravec Day 3 The Day 3 outlook will be updated by 0830Z. Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!4Yx-Jjn8g_7HL7I1JttTXVXmo7DM3_VXny3SnBCKGZ0G= FCeZEiRSBFL3DlV5K84R0GwE1rOr0dUFJzidWFvf95u3Ye4$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!4Yx-Jjn8g_7HL7I1JttTXVXmo7DM3_VXny3SnBCKGZ0G= FCeZEiRSBFL3DlV5K84R0GwE1rOr0dUFJzidWFvfICAb-3o$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!4Yx-Jjn8g_7HL7I1JttTXVXmo7DM3_VXny3SnBCKGZ0G= FCeZEiRSBFL3DlV5K84R0GwE1rOr0dUFJzidWFvfG5isKVU$=20 $$ =3D =3D =3D To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .