AWUS01 KWNH 011649

FFGMPD

COZ000-NMZ000-AZZ000-UTZ000-012200-



Mesoscale Precipitation Discussion 1542

NWS Weather Prediction Center College Park MD

1148 AM EST Sun Nov 01 2026



Areas affected...Four Corners Region



Concerning...Heavy rainfall...Flash flooding likely



Valid 011647Z - 012200Z



SUMMARY...Areas of heavy rain will expand across the Four Corners

region through 22Z, likely bringing areas of flash flooding. Peak

hourly rainfall of 0.5 to 1.0 inches can be expected along with

6-hour rainfall totals of 1 to 3 inches, especially into the

upslope regions of the San Juan Mountains.



DISCUSSION...Water vapor imagery from 1630Z showed an elongated

mid to upper-level trough over the West with two embedded

shortwaves, one over the CA/NV border and the other approaching

the northern Baja Peninsula, both advancing east. Highly

anomalous, deep layered moisture was seen streaming northeastward

into the Four Corners region on layered PW imagery, out ahead of

the advancing trough axis. Standardized precipitable water

anomalies were +4 to +6 in and around the Four Corners region with

southwesterly 700 mb winds of 40-60 kt, rapidly transporting the

moisture downstream.



While mid-level lapse rates and instability are likely to remain

poor through much of the day, some degree of daytime heating

beneath the cloud cover and rainfall should contribute to at least

weak increases in MLCAPE through 21Z. While weak instability may

boost rainfall intensity, the greater contribution to heavy

rainfall rates will come from strong ascent ahead of the upper

trough axis and orographic lift, especially into the San Juan

Mountains. Elsewhere, unidirectional flow will allow for training

and repeating rounds of heavy rain with 0.5 inches in an hour or

less at times. These high rates will lead to rapid runoff across

areas slot canyons, burn scars and other areas of vulnerable

terrain.



While steady rain will gradually increase in intensity over the

next few hours, a period of intense hourly rainfall is anticipated

ahead of the advancing upper trough within the axis of greatest

IVT, forecast to slide from west to east this afternoon. 1-2

inches of rain have already been reported over the past 6 hours

(ending 16Z) in and around the San Juan Mountains and due to heavy

rainfall over the region over the past 1-2 weeks, soil moisture

and many area rivers, waterways are running above average. The

addition of more heavy rain this afternoon could lead to locally

significant impacts.



Otto



...Please see www.wpc.ncep.noaa.gov for graphic product...



ATTN...WFO...ABQ...FGZ...GJT...PUB...SLC...



ATTN...RFC...FWR...STR...TUA...NWC...



LAT...LON   38580590 38060501 36990503 36450610 35120738 

            34840846 35010900 35990985 36441104 37401168 

            38491073 38440876