704  
FOUS30 KWBC 272034  
QPFERD  
 
EXCESSIVE RAINFALL DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
433 PM EDT THU JUL 27 2017  
   
..VALID 2033Z THU JUL 27 2017 - 12Z FRI JUL 28 2017
 
   
..REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL
 
 
MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM  
15 SSE MLS 20 W GDV 25 NE K20U 30 NW HEI 25 SW D07 20 SSE PHP  
45 S PHP 35 E IEN 40 NE AIA 10 WNW AIA 20 N BFF 25 NNE TOR  
35 NE SIB 15 ENE DRC 30 N TMH 40 NW GCC 15 SSE MLS.  
 
MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM  
45 NNE MMHO 35 S OLS 35 SE OLS 10 SW FHU 20 ENE DMA 50 N DMA  
30 E IWA 25 NNE FFZ 35 SE PRC PRC 40 NNW PRC 40 WNW 40G  
60 WNW GCN 35 SSE SGU 15 E SGU CDC 20 SE MLF 45 ENE MLF  
50 ESE U24 20 SSW PUC 25 ESE PUC 40 SSW VEL VEL 35 NNE VEL  
35 SSE RKS 30 SE BIT 35 SSE RWL 30 SSW ARL PUM 15 SE PUM  
25 ESE GXY 30 E LIC 45 ENE LAA 25 SW GCK 30 WSW PTT 15 WNW ICT  
35 S MHK 20 ENE MHK 15 NNW SZL 25 SW CPS FWC 25 W IND 15 E FWA  
15 ENE MFD 20 NE PHD 20 S AGC 10 NNW KW66 25 WNW PTB 25 N HNZ  
15 N BUY 15 S MRN 20 NW 27A 15 NNW OPN 15 W CSG 10 NNE TOI MXF  
25 ENE EET 10 S 8A0 30 NE MDQ 20 WNW DCU 15 SW 1M4 30 WNW CBM  
15 SW LIT 20 E RKR 20 NE ADH 10 ENE CHK 45 N CDS 35 S AMA CVN  
40 NE ROW 10 WSW CNM 55 WSW MRF 45 E MMCU.  
 
MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM  
50 ENE DAB 20 W OCF 25 SSW 40J 20 WSW VDI 15 NW NBC 65 SE CHS.  
 
SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM  
25 N DRO 20 SSE TEX 10 ESE TEX 25 E TEX 40 SSW GUC 40 N CPW  
25 SSE MYP 15 NE MYP 20 SE LXV 15 E CCU 35 SW BJC APA 15 ESE MNH  
25 E COS 30 NW LHX 10 WSW LHX 30 SE LHX 25 NNE SPD 30 NNE EHA  
15 WNW LBL 35 E LBL 50 E LBL 20 NNW WWR 10 SSW GAG 10 NE HHF  
20 N PPA 10 E DUX 15 W DUX 25 WSW DHT 40 WSW DHT 40 WSW TCC  
30 ENE SRR 20 SSW SRR 50 WNW SRR 15 SW 4MY 20 NE ABQ 25 SE 4SL  
15 NW AEG 20 WSW AEG 40 SSW AEG 60 SSW ABQ 45 N TCS 20 NNW TCS  
15 W TCS 35 SW TCS 15 N SVC 30 NW SVC 45 ENE SAD 25 NE SAD  
35 NNW SAD 55 SSW SOW 45 SW SOW 50 W SOW 45 SSE FLG FLG 35 E 40G  
45 E GCN 50 NE FLG 20 N INW 25 E INW 25 N SOW 15 ENE SOW  
15 SSE SJN 40 E SJN 25 NW GNT 35 WSW 4SL 20 WNW 4SL 30 NNW 4SL  
40 SSE DRO 25 N DRO.  
 
SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM  
10 SE HNB 10 SW GEZ 30 WSW AOH OSU 25 S ZZV 10 SE W22 15 NE LWB  
10 S MKJ 15 WNW TRI 25 NNE LOZ 30 SW EKQ 40 WNW CSV 15 ENE MQY  
50 NW MDQ 10 W MSL 25 ENE TUP 10 NNE TUP 20 NW TUP 25 ESE UTA  
30 W M97 10 SSE SRC 25 NNW LRF 15 N RUE 30 ESE FYV FYV  
25 SSW GMJ 10 WNW GMJ PPF 25 SSE EMP 15 NNW UKL 10 SW IXD  
35 SW SZL 30 W AIZ 15 N TBN 40 W FAM 25 SSW MWA 10 SE HNB.  
 
...CENTRAL PLAINS/MID MS VALLEY TO THE OH VALLEY/CENTRAL  
APPALACHIANS...  
 
A BROAD UPPER TROUGH IS FORECAST TO SHIFT EAST THIS PERIOD ACROSS  
THE NORTHEASTERN U.S....DRIVING A COLD FRONT EASTWARD ACROSS THE  
NORTHEAST WHILE SINKING SOUTHEAST ACROSS THE OH AND MID MS VALLEYS  
AND CENTRAL PLAINS. DEEP MOISTURE WILL CONTINUE TO POOL  
ALONG/AHEAD OF THE BOUNDARY...WITH THE GFS SHOWING PWS IN EXCESS  
OF 2 INCHES (2+ STANDARD DEVIATIONS ABOVE NORMAL) EXTENDING FROM  
EASTERN KS/OK INTO THE OH VALLEY. THIS MOISTURE INTERACTING WITH  
SHORTWAVE ENERGY MOVING ALONG THE SOUTHERN EDGE OF THE TROUGH IS  
EXPECTED TO SUPPORT MODERATE TO HEAVY TOTALS ACROSS PORTIONS OF  
THE REGION...RESULTING IN LOCALIZED FLASH FLOOD CONCERNS.  
ALSO...WITH THE LOW LEVEL FLOW ATTAINING A SIGNIFICANT WESTERLY  
TRAJECTORY PARALLEL TO THIS FRONT...THERE WILL BE POTENTIAL FOR  
TRAINING OF CELLS IN A WEST TO EAST DIRECTION...FURTHER RAISING  
THE THREAT FOR HEAVY/EXCESSIVE AMOUNTS. WHILE DIFFERING ON THE  
DETAILS...THE MODELS GENERALLY AGREE ON TWO AREAS OF HEAVIER  
TOTALS. THE MID/UPPER LEVEL SHORTWAVE ASSOCIATED WITH THE ONGOING  
CONVECTION ACROSS THE MID MS AND LOWER MO VALLEYS IS FORECAST TO  
DROP SOUTHEASTWARD...SUPPORTING MODERATE TO HEAVY AMOUNTS FURTHER  
TO THE SOUTHEAST INTO THE OZARK REGION AND PORTIONS OF THE LOWER  
OH AND TN VALLEYS. MEANWHILE...FURTHER TO THE EAST THERE IS A  
MODEL SIGNAL FOR HEAVY AMOUNTS IN ASSOCIATION WITH AN UPSTREAM  
WAVE MOVING ACROSS THE OH VALLEY TOWARD THE CENTRAL APPALACHIANS.  
 
   
..SOUTHWEST/CENTRAL AND SOUTHERN ROCKIES AND HIGH PLAINS
 
 
THE PREVIOUSLY NOTED COLD FRONT WILL ALSO BE PRESSING SOUTHWARD  
FROM THE CENTRAL PLAINS INTO THE SOUTHERN PLAINS...WITH THE  
WESTERN EXTENT BECOMING STATIONARY ALONG THE SOUTHERN TO CENTRAL  
ROCKIES. POST-FRONTAL EAST NORTHEASTERLY LOW LEVEL FLOW INTO THE  
CENTRAL TO SOUTHERN ROCKIES...ALONG WITH WEAK ENERGY MOVING AROUND  
THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE...WILL SUPPORT THE  
POTENTIAL FOR ORGANIZED CONVECTION AND MODERATE TO HEAVY RAINS  
FROM EAST CENTRAL TO SOUTHEAST CO...NORTHEAST NM INTO THE TX/OK  
PANHANDLE REGION. FURTHER WEST...ENHANCED LOW LEVEL CONVERGENCE  
ALONG A LOW LEVEL LOW/TROUGH INTERACTING WITH SUFFICIENT MOISTURE  
AND DAYTIME HEATING WILL EXTEND THE THREAT FOR HEAVY RAINS INTO  
PORTIONS OF SOUTHWESTERN NM AND SOUTHEASTERN AZ.  
 
   
..SOUTHEAST COAST
 
 
THE SURFACE WAVE IS SLOWLY MOVING OFFSHORE...TAKING WITH IT THE  
BEST LOW LEVEL MOISTURE AND CONVERGENCE. WHILE THERE IS STILL SOME  
INSTABILITY IN PLACE...THE BEST FOCUS IS EXITING...SO THE SLIGHT  
RISK WAS REMOVED...AND THE MARGINAL RISK WAS LEFT IN PLACE.  
 
   
..NORTHERN HIGH PLAINS
 
 
THE SHORTWAVE TROUGH CURRENTLY MOVING INTO THE PACIFIC  
NORTHWEST/NORTHERN CA IS FORECAST TO WEAKEN...WITH REMNANT  
SHORTWAVE ENERGY EJECTING EAST ACROSS THE TOP OF THE DOWNSTREAM  
RIDGE. THIS ENERGY ALONG WITH INCREASING MOISTURE AFFORDED BY  
STRENGTHENING SOUTHERLY LOW LEVEL WINDS IS EXPECTED TO SUPPORT  
STORMS WITH LOCALLY HEAVY AMOUNTS ACROSS PORTIONS OF SOUTHEASTERN  
MT AND EASTERN WY. MULTIPLE HIGH RES WINDOW RUNS SHOW 1.5-2 INCHES  
OF RAIN IN ISOLATED STORMS.  
 
THE MARGINAL RISK AREA WAS EXTENDED FURTHER EAST INTO WESTERN  
ND/WESTERN SD/WESTERN NE...AS THE DEVELOPING CONVECTION MAY BEING  
TO BECOME SLOWER WITH TIME. THE STORMS ARE IN THE HAIL/OUTFLOW  
DOMINATED PHASE...BUT AS THE SUPERCELLS TURN SOUTHEAST INTO THE  
MID LEVEL FLOW...THE STORMS COULD BECOME NEARLY STATIONARY FOR A  
TIME...LEADING TO AN INCREASED THREAT OF FLASH FLOODING.  
 
PETERSEN/PEREIRA/HAYES  
 

 
 
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