Quantitative Precipitation Forecast
Issued by NWS

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
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 221457
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1056 AM EDT WED JUL 22 2015

...VALID 15Z WED JUL 22 2015 - 12Z THU JUL 23 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...



AFTER LOOKING AT SOME VERY RECENT MODEL GUIDANCE AND 12Z
RAOBS..SEE NO REASON TO DEVIATE FROM EARLIER THINKING REGARDING
THE PREVIOUS THREAT AREAS.

PREVIOUS DISCUSSION FOLLOWS...


NRN INTERMOUNTAIN REGION...

AN INCREASING AREA OF SHWER/TSTMS ARE LIKELY ALONG AND BEHIND SLOW
MOVING PAC COLD FRONT PUSHING EWD AHEAD OF LONGWAVE UPR TROF ALONG
THE WEST COAST.  BROAD 85H-7H SWLY FLOW WILL DRAW INCREASING MSTR
NEWD ACRS THE REGION FROM THE POOL OF HIER PWS OVER CA...WITH
MODELS INDICATING STRENGTHENING RT ENTRANCE REGION JET DYNAMICS
LATE WED/WED NIGHT ACRS THE NRN GT BASIN INTO PORTIONS OF THE NRN
INTERMOUNTAIN REGION.  BROAD SCALE LIFT COUPLED WITH WEAK
INSTABILITY WILL LEAD TO POCKETS OF HEAVIER EMBDD RAINS ESPECIALLY
OVER PARTS OF MTNS OF ERN ID/SW MT AND WRN WY.  MODELS SUGGEST
AREAL AVG AMOUNTS OF BETWEEN .25 TO .50 INCH WITH ISOLD AMOUNTS
AROUND 1.5 INCHES IN STGR CONVECTIVE STORMS.  AS A RESULT...CAN
NOT RULE OUT ISOLD RUNOFF ISSUES ESPECIALLY OVER FAVORED
OROGRAPHIC AREAS OF WRN WY/SRN ID..AND SW MT.

ERN KS/OKLAHOMA EASTWARD INTO THE TN VALLEY...

THREAT OF HEAVY TO ISOLATED EXCESSIVE RAINS WILL CONTINUE ACRS
THIS REGION THIS PD AS DIFFERENTIAL HEATING ALONG WITH LEFTOVER
OUTFLOW BNDRIES AND CONVECTIVELY INDUCED VORT MAXES PROVIDE MAIN
TRIGGERING MECHANISMS TO PCPN...IN WHAT OTHERWISE IS VERY WEAK WLY
FLOW ABOVE A QSNTRY FRONTAL BNDRY.   EARLY MRNG/AFTN THREAT OF
HEAVIEST RAINS WILL BE AHEAD OF TRACK OF A COUPLE OF MCVS
ONE...OVER OK THE OTHER ENTERING WRN TN AS CIRCULATIONS ACT ON
DEEP MSTR...PWS OVER 2 TO 2.25 INCHES...AND MODEST CAPES.    BY
LATE WED/WED NIGHT..INCREASING WAA LIFT SHOULD HELP RE-FIRE
CONVECTION ALONG WRN PORTION OF FRONT RETURNING SLOWLY AS WARM
FRONTAL BNDRY.  MODELS DIFFER QUITE A BIT HERE AS WELL AS TOO WITH
THE NAM/NAM HI RES INDICATING A MUCH STGR 85H CONVERGENCE AXIS
COMPARED TO THE 12Z EC.   WHILE THE NAM MAY BE OVERDONE...IT DOES
HAS COMPANY IN THE CANADIAN GEM..ALBEIT NOT QUITE AS HEAVY WITH
AMOUNTS...WITH AXIS OF HEAVIER CONVECTIVE RAINS DVLPG OVER ERN
KS/NE OK.  EXPECTED MODERATE TO HIGH CONVECTIVE INSTABILITY
FEEDING INTO THE BNDRY...COULD LEAD TO SOME STG STORMS WITH SLOW
STORM MOTION EXPECTED LEADING TO SOME SHORT TERM RAINFALL RATES
EXCEEDING 2 INCHES PER HR.

SULLIVAN/TERRY
$$




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