Flash Flood Guidance
Issued by NWS
Issued by NWS
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
819 AWUS01 KWNH 210223 FFGMPD AZZ000-210700- Mesoscale Precipitation Discussion 0475 NWS Weather Prediction Center College Park MD 1023 PM EDT Thu Jun 20 2024 Areas affected...Southeast Arizona... Concerning...Heavy rainfall...Flash flooding possible Valid 210225Z - 210700Z SUMMARY...Developing thunderstorms with ample moisture flux may pose quick 1-2" totals and localized possible flash flooding conditions over the next few hours. DISCUSSION...Surface analysis depicts strong moisture surge continues through the desert southwest ahead of the tropical wave/gyre associated with former Alberto. Strong 20-25kt surface flow from the east-southeast across SW NM into SE AZ has reached a north-south barrier from upslope flow coming out of the Sonoran Desert upslope, resulting in strong moisture flux convergence. Modest mid-level lapse rates support some 1000-1500 J/kg of CAPE across the region to support/maintain stronger updrafts at the collision region. While moisture at the surface is in the 50s, it is the 850-700mb layer with .6-.75" along with the stronger winds that place the moisture flux at the 99th to maximum percentile with respect to time of year for the CIRA ALPW suite; while totals are in the 1.25-1.4 range. There will be obvious sub-cloud evaporative loss with some upslope mixing of drier air, rates of 1.5"/hr are probable given the moisture flux and updraft strength. Duration will be key for any potential localized flash flooding and given 20kts of south to north mean cell motions, this will increase duration to allow for localized 1-2". Effective bulk shear is above 30kts and should provide some longevity to the cells as well; and given orientation of steering flow to the north-south convergence line there is a low to moderate potential for some cells to cross similar paths. As such, an isolated spot of 2"+ remains possible before the pocket of instability wanes. As such, a spot or two of localized flash flooding is considered possible through the early overnight period. Gallina ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...FGZ...PSR...TWC... ATTN...RFC...CBRFC...NWC... LAT...LON 34851035 34710951 34370910 33770910 33040940 32230990 31481017 31431073 32381118 33841146 34571113