Quantitative Precipitation Forecast
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000
FOUS30 KWBC 041419
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1018 AM EDT FRI SEP 04 2015

...VALID 15Z FRI SEP 04 2015 - 12Z SAT SEP 05 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 S MTJ 15 E GUC 20 SE MYP ALS 20 SSW ABQ 40 E DUG 30 SSW OLS
25 SSE GBN 40 NNE DVT 45 NNW RQE 20 S MTJ.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 NNW JMR 20 N AXN 35 N KBAC 30 WSW K5H4 30 W KHZE 25 N K08D
35 N CWEI 10 NW CYWG 30 SE CYQK 35 NE ORB 10 N DLH 20 NNW JMR.


...CENTRAL AND EASTERN NORTH DAKOTA THROUGH NORTHWEST AND
NORTH-CENTRAL MINNESOTA...

A COLD FRONT IN CENTRAL NORTH DAKOTA...ALONG WITH A LEADING MID
LEVEL SHORTWAVE EJECTING THROUGH EASTERN ND AND NORTHERN MN...WILL
ENCOUNTER DEEP MOISTURE AND MODERATE INSTABILITY (MIXED LAYER
CAPES AT LEAST 1500-2000 J/KG) POOLED ALONG A STATIONARY FRONT.
WIDESPREAD CONVECTION AND LOCALLY HEAVY RAIN IS
EXPECTED...ALTHOUGH THE RISK OF EXCESSIVE RAINFALL AND FLASH
FLOODING IS PERHAPS NOT AS FOCUSED AS THE 00Z MESOSCALE GUIDANCE
WOULD HAVE LED ONE TO BELIEVE ACROSS EASTERN ND AND NORTHERN MN.
MID LEVEL MOISTURE CONNECTED TO THE COMPACT EARLY MORNING
SHORTWAVE MAY CONTINUE TO SUPPORT A MATURE AND PROGRESSIVE MCS
THROUGH THE EARLY AFTERNOON HOURS. PWS IN THE PRE CONVECTIVE
ENVIRONMENT WILL BE AROUND 1.70 INCHES PER THE 12Z ABERDEEN RAOB.
THESE VALUES PEAK IN THE MODELS BETWEEN 1.75-2.00 INCHES IN THE
VICINITY OF CONVECTION...THUS RISING TO 3+ STANDARD DEVIATIONS
ABOVE NORMAL...AND SUGGESTING AT LEAST BRIEF HEAVY RAIN RATES. IT
IS IN THE WAKE OF THIS MCS...IF INSTABILITY CAN RECOVER
SUFFICIENTLY...THAT A MORE PRONOUNCED HEAVY RAIN THREAT COULD
DEVELOP DURING THE EVENING HOURS...AS LOW LEVEL FLOW ACCELERATES
INTO THE BACK SIDE OF THE SHORTWAVE...OVER ND/MN.

IN ADDITION TO THIS POSSIBILITY...WESTERN/CENTRAL ND WILL SEE
BANDS OF SOUTH TO NORTH ORIENTED CONVECTION THROUGH EARLY
AFTERNOON...ASSOCIATED WITH JET DYNAMICS AND FRONTOGENESIS
ASSOCIATED WITH THE LARGER SCALE TROUGH IN THE WESTERN U.S. IT
APPEARED THAT THE INFLECTION POINT IN THE FLOW...AND GREATER
POTENTIAL FOR FLASH FLOODING WOULD BE LOCATED NORTH OF THE U.S.
BORDER...BUT A MODEST COMBINATION OF INSTABILITY AND PRECIPITABLE
WATER VALUES ABOVE 1 INCH MAY SUPPORT LOCAL 2 INCH RAIN AMOUNTS
OVER A SHORT TIME...AND SOME LOW PROBABILITIES OF EXCEEDING FLASH
FLOOD GUIDANCE. THIS ACTIVITY IS EXPECTED TO WANE BY MID AFTERNOON
AS SHORTWAVE RIDGING DEVELOPS WITHIN THE LARGER SCALE FLOW.


...ARIZONA...WESTERN NEW MEXICO...SOUTHWEST AND SOUTH-CENTRAL
COLORADO...

THE MONSOON CONTINUES...WITH PRECIPITABLE WATER VALUES STILL
RUNNING A BIT ABOVE AVERAGE (1-2 STANDARD DEVIATIONS PER THE
ENSEMBLES)... INCLUDING A SUBTROPICAL CONNECTION TO HIGH ALTITUDE
MOISTURE STREAMING NORTH FROM TROPICAL STORM KEVIN AS PER THE
700-500 AND 500-300 CIRA LAYER PW LOOPS. THE SIGNAL FOR HEAVY
RAINFALL IS NOT AS EVIDENT BY BOTH THE GLOBAL AND HI-RES GUIDANCE
AS COMPARED TO YESTERDAY...THOUGH ONCE AGAIN ALSO REMAINS TIED TO
THE TOPOGRAPHY IN SOUTHEAST AZ INTO WESTERN NM AND
SOUTH-CENTRAL-CENTRAL CO. AS WAS NOTED IN THE PREVIOUS
DISCUSSION...A LIMITING FACTOR FOR WIDESPREAD HEAVY RAIN WILL BE
WEAK WINDS BELOW 600 MB...SO STORMS MAY BECOME OUTFLOW DOMINANT
RATHER QUICKLY. ALSO... THE UPPER LEVEL DEBRIS CLOUDS FROM T.S.
KEVIN AND PRIOR CONVECTION MAY ALSO LIMIT THE DESTABILIZATION
SOMEWHAT. ISOLATED FLASH FLOODING WILL NEVERTHELESS BE
POSSIBLE...INCLUDING OVER THE PHOENIX METRO AREA PER THE LATEST
AFOREMENTIONED SSEO NEIGHBORHOOD PROBABILITIES (WHICH CLIMB TO
30-50% BY MIDDAY).

BURKE/HURLEY
$$





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