FOUS30 KWBC 311958 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 358 PM EDT Sun May 31 2026 Day 1 Valid 16Z Sun May 31 2026 - 12Z Mon Jun 01 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF MONTANA TO THE BLACK HILLS, CENTRAL MISSOURI, AND THE SOUTHEAST UNITED STATES... Missouri... Raised a Slight Risk for central Missouri. Ongoing progressive activity across a stationary front is generally producing 1-2" rainfall over central Missouri. 12Z guidance is in pretty good agreement on an MCS tracking over Missouri late tonight. That should be fairly progressive as well, but veering of the low level flow may make for inflow parallel to the orientation and increased duration overnight. Much of this area has lower FFG (generally 2"/3hr), so the combination of these two rounds could cause scattered flash flooding. Will need to monitor CAMs/boundaries for further details to this overnight activity. The RRFS is hotter than other models as usual, but the 12Z is notable a broader span of coverage from the KC metro to the StL metro, so either of those could be in greater play tonight and warrant a Slight expansion to them. Montana to the Black Hills... Maintained the Slight Risk for portions of Montana and nearby Wyoming and the far western Dakotas, now including more of the Black Hills. Rainfall intensity will remain lower than yesterday, but an additional 1-2" brings flooding concerns, especially where the 3hr FFG is below 1.5" in north-central MT and western SD. Southeast US... Maintained the Slight Risk along a cold front over southern GA/northern FL into southeast AL given agreement of 12Z CAM guidance focusing 1-3"+ QPF on this area. PW rises from 2 to 2.25" and MLCAPE should reach 2000 J/kg this afternoon supporting heavy rain. Repeating activity is expected with 20kt Wly deep layer flow keeping activity alive along the frontal forcing. Activity over the eastern FL peninsula will need to be monitored. As of now the Marginal Risk was expanded over Cape Canaveral on account of sea breeze based convection possibly getting held up there. The focus may be just west of Miami, but will continue to monitor. Elsewhere...trimmed the broad Marginal Risk where possible including in eastern MS and western KY. Expanded east a bit in MN/IA and southeastern KY given 12Z consensus. Frontal and low levels boundaries will provide some focus in the Gulf-sourced moisture plume and the broad pool of instability. Jackson Day 2 Valid 12Z Mon Jun 01 2026 - 12Z Tue Jun 02 2026 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF THE NORTHERN ROCKIES, GREAT PLAINS, AND MID-SOUTH... Northern Rockies... Precipitation lingers over northwest Montana as a slow moving mid- and upper-level system lingers over the Canadian border. The cumulative effect of the additional 1-2" rain (12Z HREF and REFS consensus) maintains a limited risk for additional flooding concerns. Central Plains... Expanded the Marginal Risk more into Northeast Colorado and into more of north-central Oklahoma while trimming out the heart of the Nebraska Sandhills. SSEly low level flow will increase over the central Plains through the morning and promote strong diurnal heating. Late afternoon High Plains activity should track east over the central Plains. Mid-South... MCS activity is expected tonight over Missouri. This should track from southeastern MO and over much of the Mid-South through the morning with potential for additional evening activity along remnant boundaries. Moist low level flow veers westerly late tonight over the region which should be parallel to at least segments of the activity and increase heavy rainfall duration at least locally. 12Z CAM consensus paints a fairly decent heavy QPF footprint across the Mid-South with 1-3"+ likely through the day. The 18Z HRRR essentially agrees with the tracks of 12Z CAMs along with the later additional activity. Raised a Marginal Risk for the Mid- South on account of the ingredients and CAM output along with 3hr FFG around 2.5". West Texas into New Mexico... South-southeasterly low level flow intensifies Monday afternoon, promoting decent westward expansion of Gulf moisture across the Pecos River Valley to the Sacramento Mountains and south to the Big Bend. Diurnally driven activity is a sure bet on the Davis and Sacramento Mtns. How much activity spreads from the terrain remains to be seen. For now the Marginal Risk was trimmed a bit on the north and expanded over the Big Bend based on 12Z CAM consensus. Jackson Day 3 Valid 12Z Tue Jun 02 2026 - 12Z Wed Jun 03 2026 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF EASTERN NEW MEXICO AND WEST TEXAS... ...West Texas into New Mexico... Southeasterly low level flow backs further easterly Tuesday bringing more Gulf-sourced moisture across West Texas and southeast New Mexico than was present on Monday. Terrain driven activity should spread across this area with QPF generally in the 1-2" range. Slow moving activity should result in scattered flash flooding, especially over sensitive areas such as burn scars and steeper terrain. The Slight Risk was trimmed a bit to exclude El Paso based on 12Z consensus QPF. ...Great Plains... Warm moist air surges up the Plains in earnest starting Monday night. Sufficient shear from a trough over the Northern Rockies, forcing along a low level convergence zones, and early June heating should promote heavy/potentially organized thunderstorms throughout the Great Plains. A Marginal Risk is maintained from the Dakotas to the Texas Panhandle. ...North Florida through the Gulf Coast... A Marginal Risk has been raised from east Texas through the Florida/Georgia border. A slow moving cold front stretching from Georgia to east Texas Tuesday morning drifts south through the Gulf Coast Tuesday night. High moisture laden air pools ahead of the front with a 2" PW swath from north FL to east Texas in the afternoon which is 2 sigma above normal. Repeating heavy thunderstorms should occur along this corridor and result in a localized flash flood risk. Jackson Day 1 threat area: https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt Day 2 threat area: https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt Day 3 threat area: https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt