Quantitative Precipitation Forecast Discussion NWS Weather Prediction Center College Park MD 501 PM EDT Wed May 30 2018 Prelim Day 1, Day 2 and Day 3 QPF Discussion Valid May 31/0000 UTC thru Jun 03/0000 UTC Reference AWIPS Graphics under...Precip Accum - 24hr Day 1 ...Upper Great Lakes and Midwest... Alberto is expected to continue tracking progressively to the north, producing locally heavy amounts near the center as it tracks from Indiana across Lower Michigan this evening overnight, with additional moderate to locally heavy amounts continuing to develop further west across Wisconsin and Minnesota as moisture streaming out ahead of the center interacts with an approaching negatively-tilted upper trough. WPC QPF reflects consensus of the 12z hi-res models, which continued to maintain a good signal for 1-2 inch amounts, with locally heavier amounts from northern Indiana into western Lower Michigan this afternoon and evening. ...Central Plains to the lower Ohio and Tennessee valleys... While showing some differences in the details, the 12z hi-res models runs continue to show a good signal for developing moderate to heavy rains this evening-overnight as a shortwave trough moving out of the central Rockies interacts with moisture pooling along a stationary boundary extending along the Kansas-Oklahoma border. Convection is expected to wane Thu morning as the lead shortwave moves across the mid Mississippi valley before redeveloping further downstream across the lower Ohio and Tennessee valleys, with upstream energy possibly spurring some additional redevelopment across the mid Mississippi valley later in the day as well. WPC QPF gave significant weighting to the HREF Mean through most of the period. ...Lower Great Lakes / Upper Ohio valley / Central Appalachians / Mid Atlantic... As the aforementioned trough over the upper Midwest translates eastward this period, a northwest-southeast oriented boundary and the leading edge of a very moist airmass extending from the Mid-Atlantic from the Great Lakes is expected to move north this period. Guidance shows deep moisture surging north along the central Appalachians and Mid-Atlantic as the low level flow backs ahead of the approaching trough. This moisture along with afternoon heating and the larger scale forcing afforded by the approaching trough is expected to support and increasing threat for moderate to locally heavy amounts both along the higher terrain and ahead of a cold front pushing across the lower Great Lakes late Fri. WPC QPF gave significant weighting to the HREF Mean through most of the period. ...Northern Intermountain West / Northern Rockies and High Plains... As an upper level trough continues to amplify across the Northwest, a developing upper jet couplet along with ample moisture along the low to mid level boundary there remains a good signal for widespread light to locally heavier amounts across the region. WPC QPF reflects a consensus of the hi-res models here as well. Days 2/3... ...Northern Rockies into Northern Plains... A baroclinic zone extending from Northern High Plains to Great Basin will move eastward to the Upper/Middle Mississippi Valley into the Southern Plains by Saturday evening. As the system moves out of the Rockies into a plume of moisture with precipitable water values of 1.25 to 1.00 inches over the Northern Plains on Thursday evening into Friday evening producing convection over the Northern Plains with maximum qpf amounts ranging from 1.50 to 2.00 inches. A secondary maximum will develop under the associated upper-level low with maximum qpf amounts ranging from 1.20 to 1.00 inches. Overnight Friday, moisture will surge into the Plains with precipitable water values of 1.50 inches and the moisture increasing again over the Middle Mississippi Valley with precipitable water values of 1.75 inches by Saturday evening. The system will produce maximum qpf over the Central Plains with qpf amounts ranging from 2.20 to 2.00 inches on Friday evening into Saturday evening. A secondary maximum will also develop over parts of the Northern Plains with maximum qpf amounts ranging from 1.75 to 2.00 inches. The high qpf amounts on Thursday evening into Friday evening and Friday evening into Saturday evening prompted the placement of a slight risk of excessive rainfall over the Northern Rockies into the Northern Plains and over parts of the Northern/Central Plains. ...Ozarks into the Northeast and the Mid-Atlantic... Another baroclinic zone extending from the Great Lakes into the Central Plains will move off the Northeast/Northern Mid-Atlantic Coast extending westward to the Middle Mississippi Valley by Saturday evening. Moisture will pool along the boundary with precipitable water values ranging from 1.75 to 1.50 inches through Saturday evening. The system will produce maximum qpf amounts ranging from 1.25 to 0.75 inches over the Southern Ohio/Tennessee Valleys on Thursday evening into Friday evening with a secondary maximum over the Ozarks with maximum qpf amounts ranging from 1.00 to 0.75 inches. As the system moves east the maximum qpf amounts will range from 0.75 to 0.50 inches over the Mid-Atlantic on Friday evening into Saturday evening. ...Florida... Short wave moving over the Florida panhandle will move into moisture with precipitable water values ranging from 1.75 to 2.00 inches. The energy will produce convection over the central portion of the peninsula producing maximum qpf amounts ranging from 1.00 to 1.20 inches on Thursday evening int Friday evening. Pereira/Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/qpf/qpf2.shtml