Quantitative Precipitation Forecast
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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 50

000
FOUS30 KWBC 051402
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1002 AM EDT TUE MAY 05 2015

...VALID 15Z TUE MAY 05 2015 - 12Z WED MAY 06 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
40 NNE GCK 30 NE WWR WDG 20 S BVO 15 E OKM 20 SE DUA 10 S GDJ
30 NW 6R9 15 NW SJT 35 NNW BPG 25 NW LBB 25 SSW DHT 35 W CAO
15 SSW VTP 20 NNE ALS 25 ENE MYP 30 SE CCU 25 ENE CCU 30 E 20V
30 ENE 20V 40 SW PUM 30 W PUM 10 N VDW 20 W IBM 35 WNW OGA
15 ESE OGA 35 SW MCK 40 NNE GCK.


15Z UPDATE...

MCV DEPICTED FROM KLBB RADAR LOOPS IS CONTINUING TO PUSH E-NE
ACROSS NORTH TX...WITH THE DEEP-LAYER MUCAPE NOW EXHAUSTED ACROSS
WHAT WAS THE MODERATE RISK AREA. STRONG UPPER LEVEL DIFFLUENCE
CONTINUES...BUT A WEAKENING/VEERING LLJ ALONG WITH THE MINIMAL
INSTABILITY WILL SHIFT THE EXCESSIVE RAINFALL POTENTIAL FARTHER
DOWNSTREAM...AND AT A LATER TIME (THIS AFTN) WITH THE DAYTIME
HEATING (DEPENDING ON HOW QUICKLY THE MCS UPPER CLOUD SHIELD THINS
OUT).

HURLEY


PREVIOUS DISCUSSION BELOW...


...WEST TX / OK / ADJACENT PORTIONS OF NM/CO/KS...

MAINTAINED A BROAD SLIGHT RISK AREA IN PARTS OF CO/KS/OK/TX/NM TO
ENCOMPASS SUSTAINED SOUTHERLY LOW LEVEL FLOW AND LARGE SCALE UPPER
LEVEL FORCING WHICH SLIDES THROUGH THE SOUTHERN PLAINS IN THE NEXT
24-30 HOURS. WHILE THIS KEEPS CONTINUITY FROM PREVIOUS FORECASTS
AND COVERS THE MODEL CONSENSUS FOR MODERATE TO HEAVY
PRECIPITATION...CONFIDENCE IN ANY SPECIFIC FLASH FLOOD EVENT IS
LOWER THAT IT WAS FOR THE WEST TEXAS EVENT. HEIGHT FALLS WILL BE
MAXIMIZED FARTHER NORTH TOWARD KS/NE...BUT GREATER MOISTURE DEPTH
IS EXPECTED ALONG THE TAIL END OF THOSE HEIGHT FALLS...SUPPORTING
A HEAVY RAIN ENVIRONMENT OVER PRIMARILY OK/TX DURING THE AFTERNOON
AND TUESDAY NIGHT. THE QPF DETAILS APPEARED BETTER HANDLED BY THE
00Z WRF-ARW AND GEM REGIONAL...AS WELL AS THE GFS AND 12Z ECMWF.
THE MODEL SIGNAL IS NOT PARTICULARLY HEAVY...BUT WITH STRONGLY
MERIDIONAL FLOW AND PW VALUES RISING TO AROUND 1.5 INCHES WITHIN A
PLUME EXTENDING NORTHWARD FROM THE SE TX COAST...THERE IS
POTENTIAL FOR TRAINING CELLS TO PRODUCE MORE THAN 2 INCHES IN AN
HOUR LOCALLY. THE FLASH FLOOD GUIDANCE VALUES OF ROUGHLY 2.0 TO
2.5 INCHES IN 1 HOUR OR 2.50 - 3.0 INCHES IN 3 HOURS COULD BE
EXCEEDED...ESPECIALLY OVER THE FAR EASTERN TX/OK PANHANDLES INTO
WRN OK...AND DEVELOPING FROM NORTH TX INTO SOUTHERN AND CENTRAL OK
WHERE A READY SUPPLY OF RICH MOISTURE AND MODERATE INSTABILITY MAY
BE MORE SUSTAINABLE.


...EASTERN CO / WESTERN KS / FAR SW NE...

UPSLOPE INTO THE HIGHLANDS OF FAR NORTHEAST NM AND SOUTHERN CO
WILL BE LIMITED TO THE EARLY MORNING HOURS DURING THE DIURNAL
MINIMUM OF INSTABILITY. STILL...INCREASING MID/UPPER
LIFT...WORKING WITH PW VALUES OF 0.75 INCHES TO NEAR 1.0
INCH...WILL PROMOTE WIDESPREAD RAINFALL TO FURTHER SATURATE THE
GROUND ABOVE WHAT CONVECTION HAD ACCOMPLISHED MONDAY NIGHT. DURING
THE AFTERNOON...LIGHT UPSLOPE FLOW SHOULD PERSIST NEAR AND NORTH
OF THE PALMER DIVIDE AT LEAST DURING THE 18-21Z PERIOD...WHILE
MIGRATION OF THE SYNOPTIC TROUGH THROUGH THIS REGION WILL
GRADUALLY ENCOURAGE VEERING OF LOW LEVEL FLOW...WITH A SURFACE
TROUGH AXIS MIGRATING OUT TOWARD KANSAS AND FAR NORTHEAST CO BY
00Z. WHILE THE STRENGTH AND PERSISTENCE OF THE UPSLOPE IS NOT
IDEAL FOR HEAVY RAIN...OTHER FACTORS...SUCH AS ANTECEDENT
RAINFALL...PW VALUES OF 0.75 INCHES ALL THE WAY WEST OF I-25...AND
PASSAGE OF THE COLDEST MID LEVEL TEMPERATURES THROUGH CENTRAL
COLORADO THIS AFTERNOON...SUGGEST A RISK OF FLASH FLOODING. AS
NOTED BY THE NWS BOULDER FORECAST OFFICE...THE PREDICTED PW VALUES
WOULD BE A RECORD FOR THE DATE.

THOUGH ANTECEDENT CONDITIONS ARE NOT AS RIPE ON THE EASTERN PLAINS
AND OVER ADJACENT KS/NE...LOW LEVEL MOISTURE TRANSPORT WILL FOCUS
THERE...AND WITH LARGELY MERIDIONAL FLOW...SOME TRAINING OF CELLS
FROM SOUTH TO NORTH COULD PRODUCE A FLASH FLOOD RISK.


...WESTERN NE / SOUTHWEST SD...

UPSLOPE WILL DEVELOP INTO WESTERN NE AND SW SD / THE BLACK HILLS.
PW VALUES DO BECOME ANOMALOUSLY HIGH AT THIS LONGITUDE AS THE 0.75
INCH VALUES COME CLOSE TO RAPID CITY BY TUESDAY EVENING. THIS
WOULD BE OF GREATER CONCERN EXCEPT THAT THE MODEL QPFS ARE QUITE
TAME FOR NOW...LIKELY OWING TO WEAK INSTABILITY. STILL...A HEAVY
RAIN THREAT COULD DEVELOP SHOULD HEATING AND DEEP LAYER LIFT PROVE
SUFFICIENT TO BOOST INSTABILITY AND SUPPORT HEAVIER CONVECTIVE
RAIN RATES. WILL WATCH THE MODEL CAPE AND QPF TRENDS FOR A
STRONGER SIGNAL...AND POSSIBLE INTRODUCTION OF A SLIGHT RISK OF
EXCESSIVE RAINFALL OVER THIS REGION.

BURKE
$$





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.