952
FXUS04 KWBC 030901
QPFPFD
QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
500 AM EDT SUN JUN 03 2018
PRELIM DAY 1, DAY 2 AND DAY 3 QPF DISCUSSION
VALID JUN 03/1200 UTC THRU JUN 06/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR
..EASTERN U.S.
THE STUBBORN, COMPACT MID-UPPER LEVEL TROUGH ACROSS THE MID
ATLANTIC REGION WILL FINALLY PUSH OFFSHORE LATER SUN AND SUNDAY
NIGHT. THE MOIST CYCLONIC FLOW ALONG WITH THE CONTINUED ANOMALOUS
PWS (1.75-2.00") WILL MAINTAIN A THREAT FOR EXCESSIVE RAINFALL,
ESPECIALLY EARLY IN THE PERIOD WITH THE BETTER FORCING AND GREATER
INSTABILITY SOUTH OF THE SURFACE FRONTAL BOUNDARY. BY MID-LATE
AFTERNOON, THE SURFACE FRONT WILL SLIDE SOUTH TO NEAR THE VA/NC
BORDER, AS WILL THE HIGHEST 1-3 HOUR RAINFALL RATES PER THE HREF
PROBABILITIES. WPC WILL MAINTAIN A SMALL SLIGHT RISK AREA ACROSS
PORTIONS OF CENTRAL AND SOUTH-CENTRAL VA INTO EASTERN VA AND
SOUTHERN MD BASED ON THE HIGHER POTENTIAL FOR HEAVY ADDITIONAL
RAINFALL AMOUNTS (PER THE MULTI CAM CONSENSUS), ALONG WITH THE LOW
FFG VALUES (1 HOUR FFGS OF 1" OR LESS). WPC QPF COMPRISED A BLEND
OF A 00Z MULTI-MODEL CONSENSUS (INCLUDING HREF MEAN AND NBM) ALONG
WITH CONTINUITY (PREVIOUS FORECAST).
..GREAT LAKES/OHIO VALLEY INTO THE NORTHEAST
A NEGATIVELY-TILTED UPPER TROUGH WILL CONTINUE TO PUSH SHOWERS AND
EMBEDDED THUNDERSTORMS EASTWARD ACROSS THE GREAT LAKES AND OHIO
VALLEY TODAY, WITH THE ACTIVITY THEN SPREADING INTO THE NORTHEAST
OVERNIGHT AHEAD OF THE OCCLUDED SURFACE FRONT. THE PROGRESSIVE
NATURE OF THE SYSTEM ALONG WITH LIMITED/NEGLIGIBLE INSTABILITY
SHOULD LIMIT THE POTENTIAL FOR HEAVY AMOUNTS, HOWEVER THE RIDGE OF
HIGHER (ANOMALOUS) PWS AHEAD OF THE UPPER TROUGH AND SURFACE
OCCLUSION REMAINS RATHER IMPRESSIVE, AND AS SUCH EVEN WITHOUT MUCH
IF ANY CAPE WELL IN THIS REGION WELL NORTH OF THE WARM SECTOR,
MODERATE TOTALS AVERAGING 0.25-0.50+ INCH ARE LIKELY PER THE
MULTI-MODEL CONSENSUS.
..SOUTHERN ROCKIES/HIGH PLAINS
GUIDANCE CONTINUES TO SHOW A GOOD SIGNAL FOR DEVELOPING
PRECIPITATION, WITH LOCALLY HEAVY AMOUNTS POSSIBLE ACROSS MUCH OF
NM INTO SOUTHWEST AND SOUTH-CENTRAL CO (ESPECIALLY DURING THE
AFTERNOON AND EVENING). INCREASING SOUTHEASTERLY LOW-LEVEL INFLOW
AHEAD OF A WELL DEFINED, COMPACT MID-UPPER LEVEL SHORTWAVE MOVING
ACROSS THE FOUR CORNERS REGION IS EXPECTED TO SUPPORT DEVELOPING
SHOWERS AND STORMS DURING THE AFTERNOON AND EVENING HOURS, WITH A
MULTI-CAM SIGNAL FOR MODERATE TO LOCALLY HEAVY AMOUNTS ACROSS THE
SOUTHERN COLORADO AND THE NEW MEXICO RANGES.
DAY 2
..NORTHEAST
A CLOSING LOW IN THE NEGATIVELY TILTED MID TO UPPER LEVEL TROUGH
DEEPENS MONDAY OVER THE ONTARIO/QUEBEC BORDER. MODEL DIFFERENCES
PERSIST WITH TIMING AND STRENGTH OF SHORTWAVE IMPULSES ROUNDING
THE LOW. THE MOST NOTABLE EFFECT OF THESE SHORTWAVE DIFFERENCES IS
POSITION OF THE SURFACE LOW TO THE COAST AND ASSOCIATED QPF MAX.
THE 00Z NAM IS THE CLOSEST TO THE COAST, WHILE THE 00Z GFS/ECMWF
ARE MORE OFFSHORE WITH THE MAX (WITH THE ECMWF SPREADING MODERATE
PRECIP FARTHEST INLAND). A BLEND OF THE 00Z GFS/ECMWF/NAM WITH
PREFERENCE TO THE GFS WAS THE BASIS FOR QPF.
..SOUTHERN PLAINS
A SHORTWAVE TROUGH ROUNDING THE BROAD SUBTROPICAL RIDGE CENTERED
OVER NORTHWEST MEXICO WILL PUSH ACROSS KS MONDAY. ORGANIZED
CONVECTION IS POSSIBLE AHEAD OF THIS THROUGH AS HEIGHT FALLS OCCUR
OVER GULF MOISTURE (1.5 INCH PW IS 1.5 STANDARD DEVIATIONS ABOVE
NORMAL). ONE LIMITING FACTOR IS A PREFERENCE TO FORWARD
PROPAGATION AND PROGRESSION. A MARGINAL RISK OF EXCESSIVE RAINFALL
WAS MAINTAINED ALONG THE OK/TX BORDER. QPF WAS MAINLY A BLEND OF
THE 00Z GFS AND NAM.
..GULF COAST OF TX TO FL
SCATTERED CONVECTION LIKELY ALONG A COLD FRONT PRESSING SOUTHWARD
OFF THE CENTRAL GULF COAST---INTO NORTH FLORIDA AND EAST TEXAS.
LIGHT FLOW ALOFT WILL MAKE FOR SCATTERED CONVECTION...OFTEN HEAVY
WITH 1.75 INCH PW.
..NORTHERN PLAINS
A SHORTWAVE TROUGH OVER ALBERTA MONDAY NIGHT WILL TAP GULF-SOURCED
MOISTURE OVER MT/ND WITH LOCALLY HEAVY RAIN PARTICULARLY NEAR THE
BORDER. QPF BASED MAINLY ON THE 00Z GFS/NAM.
DAY 3
..THE EAST
THE DEEPENED LOW OVER ONTARIO/QUEBEC EJECTS EAST TO NEW ENGLAND
TUESDAY. STRONG SOUTHEAST LOW LEVEL FLOW WILL CONTINUE AHEAD OF
THE SURFACE LOW MOVING FROM OFF THE SOUTHEAST NEW ENGLAND COAST TO
THE SOUTH COAST OF NOVA SCOTIA. TIMING AND AMPLIFICATION
DIFFERENCES ISSUES CONTINUE. WPC QPF IS BASED ON A BLEND OF THE
00Z GFS/NAM/ECMWF. MODERATE TO HEAVY PRECIP POTENTIAL IS GREATEST
ACROSS CENTRAL TO EASTERN MAINE IN THE REGION OF STRONGEST ONSHORE
FLOW.
..LOWER GREAT LAKES INTO THE NORTHERN MID-ATLANTIC
ADDITIONAL HEIGHT FALLS ROTATING SOUTHEAST INTO THE MEAN TROUGH
POSITION ACROSS SOUTHEAST CANADA WILL HELP PUSH A COLD FRONT SOUTH
TO THE MID-ATLANTIC. THE 00Z GFS WAS A SOUTHERN OUTLIER WITH THE
AXIS OF PRECIP ASSOCIATED WITH THIS FRONT. WPC FAVORED A BLEND OF
THE 00Z GFS/NAM/ECMWF.
.SOUTHERN PLAINS TO LOWER MS VALLEY
CONVECTION MAY FIRE IN THE NORTHWESTERLY MID TO UPPER LEVEL FLOW
PARALLEL TO THE SURFACE FRONT OVER THE SOUTHERN PLAINS OR THE
LOWER MS VALLEY TUESDAY. THE 00Z ECMWF CAME IN MUCH WETTER AND
FARTHER EAST THAN ANY OTHER GUIDANCE WHILE THE 00Z GFS AND NAM
WERE SIMILAR WITH THE POTENTIAL MODERATE TO HEAVY QPF AXIS FROM
WESTERN TO CENTRAL OK INTO NORTHEAST TX AND WESTERN LA. WPC QPF
FAVORED THE WESTERN SOLUTIONS WITH A NOTE TO FUTURE SHIFTS TO
MONITOR THIS CLOSELY GIVEN PW APPROACHING 2 INCHES.
HURLEY/JACKSON
GRAPHICS AVAILABLE AT WWW.WPC.NCEP.NOAA.GOV/QPF/QPF2.SHTML
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