Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 300655
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
254 AM EDT THU JUL 30 2015


PRELIM DAY 1 QPF DISCUSSION
VALID JUL 30/1200 UTC THRU JUL 31/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1


...NM/SOUTHERN PLAINS...

THE COMBINATION OF MOISTURE AND INSTABILITY FOCUSED ON A FRONTAL
BOUNDARY ACROSS THE SOUTHERN PLAINS...AND THE HIGHER TERRAIN OF
NM...WILL FUEL CONVECTION WITH HEAVY TO EXCESSIVE RAINFALL DURING
DAY 1. FOR THE MOST PART...THE WPC QPF WAS BASED ON A BLEND OF THE
00Z GFS/12Z ECMWF...WITH THE 12Z SSEO MEAN AND 00Z WRF ARW USED TO
BETTER DELINEATE THE HIGHEST QPF MAXIMA.

MUCH OF THE EARLY MORNING ACTIVITY HAS BEEN FOCUSED ON NORTHEAST
NM...AS THE ACTIVITY REFORMS ON THE EDGE OF A INSTABILITY AXIS AND
1.40 INCH PRECIPITABLE WATER STRIPE. THE MOISTURE AND INSTABILITY
BECOME FOCUSED ON A FRONT EXTENDING ACROSS NORTHEAST NM INTO NORTH
TX AND CENTRAL OK. PRECIPITABLE WATER VALUES NEAR 2.00
INCHES...COUPLED WITH MODERATE TO STRONG INSTABILITY...WILL FEED
DEVELOPING CONVECTION ALONG THIS LINE BEFORE 30/18Z. THERE IS SOME
MODEL SPREAD ON JUST HOW LONG THE ACTIVITY LASTS...WITH THE 00Z
NAM BASED GUIDANCE SUGGESTING A DROP OFF IN INSTABILITY FOR A TIME
DURING THE LATE AFTERNOON AND EARLY EVENING.

HOWEVER...A DEVELOPING LOW LEVEL SOUTHERLY JET FEEDS MOISTURE BACK
INTO THE SOUTHERN PLAINS AFTER 31/0Z...USING THE FRONT AS A FOCUS.
AN AXIS OF 0.75 TO 1.25 INCHES OF QPF WAS PLACED ALONG THIS
FRONT...ACCOUNTING FOR BOTH CONVECTIVE ROUNDS. ACROSS THE SOUTHERN
PLAINS (OK INTO SOUTHERN KS)...ONE AND THREE HOUR FLASH FLOOD
GUIDANCE VALUES ARE GENERALLY HIGHER THAN 2.00 INCHES. WHILE HEAVY
RAIN IS EXPECTED IN THESE AREAS...ORGANIZED FLASH FLOODING IS NOT
EXPECTED AT THIS TIME.

OVER NM...THE CONVECTION INITIALLY BECOMES ANCHORED TO THE
TERRAIN...MAINLY ACROSS NORTHERN AND WESTERN PORTIONS OF THE
STATE. AS WAS THE CASE ON WED...THE CONVECTION FEEDS ON MODERATE
INSTABILITY AND PRECIPITABLE WATER VALUES NEAR 1.25 INCHES AND
MOVES OFF THE TERRAIN IN THE LATE AFTERNOON AND EARLY EVENING.
LOCAL 0.75 TO 1.25 INCH QPF AMOUNTS ARE EXPECTED ACROSS THE HIGHER
TERRAIN (WITH AMOUNTS AS HIGH AS 2.50 INCHES SUGGESTED BY THE 00Z
NAM/GFS)...WHERE ONE AND THREE HOUR FLASH FLOOD GUIDANCE VALUES
AREA AS LOW AS AN INCH OR LESS. DUE TO PREVIOUS HEAVY
RAINFALL...AND THE POTENTIAL FOR HIGH RAINFALL RATES...A SLIGHT
RISK AREA WILL BE PLACED OVER PORTIONS OF NORTHERN AND WESTERN
NM...MAINLY IN THE HIGHER TERRAIN.


...AZ/SOUTHERN CA...

THE MONSOONAL FLOW CONTINUES TO PUMP HIGH MOISTURE CONTENT AIR
INTO MAINLY CENTRAL AND WESTERN AZ AND NEARBY SOUTHERN CA. THE
MONSOONAL MOISTURE... COMBINED WITH MODERATE INSTABILITY...FUELS
CONVECTION THAT PRODUCES HEAVY TO EXCESSIVE RAINFALL...ESPECIALLY
OVER SOUTHWEST AZ AND NEARBY SOUTHERN CA. THERE WAS DECENT MODEL
AGREEMENT WITH THE OVERALL SYNOPTIC PATTERN...AND THE WPC QPF WAS
BASED MAINLY ON A MULTI MODEL BLEND. THE 00Z WRF ARW AND 12Z SSEO
MEAN WERE USED TO BETTER DELINEATE THE HIGHER TERRAIN QPF...MAINLY
ACROSS SOUTHEAST AZ.

CONVECTION SHOULD REFORM EARLY THIS AFTERNOON ACROSS AZ/SOUTHERN
CA...AS MONSOONAL MOISTURE (WHICH IS DEPICTED WELL BY THE HIGH AND
MID LEVEL LAYERED PRECIPITABLE WATER IMAGES) POURS NORTHWARD
ACROSS AZ INTO SOUTHEAST CA. PRECIPITABLE WATER VALUES TOP OUT
NEAR 1.75 INCHES ACROSS SOUTHWEST AZ DURING THE AFTERNOON AND
EVENING HOURS...AND THE MOISTURE (AS WELL AS MODERATE INSTABILITY)
BECOME FOCUSED ON A SURFACE TROUGH EXTENDING FROM WESTERN AZ INTO
SOUTHEAST CA. THERE IS A MODEL SIGNAL THAT A SHORT WAVE IN THE MID
LEVEL FLOW COULD HELP FOCUS CONVECTION ACROSS CENTRAL AND WESTERN
AZ...BUT THE BUILDING MID LEVEL RIDGE COULD MITIGATE THE LOCAL
SYNOPTIC LIFT IT PROVIDES. IN ANY EVENT...LOCAL 0.50 TO 1.00 INCH
QPF AMOUNTS ARE EXPECTED ACROSS
THE HIGHER TERRAIN IN MUCH OF AZ. ONE AND THREE HOUR FLASH FLOOD
GUIDANCE VALUES ARE AS LOW AS AN INCH IN THESE AREAS. GIVEN THE
POTENTIAL FOR HIGH RAINFALL RATES...A SLIGHT RISK AREA WAS
INTRODUCED FOR PORTIONS OF CENTRAL AND EASTERN AZ...MAINLY NEAR
THE TERRAIN.

FURTHER WEST...THE MAIN FOCUS FOR CONVECTION SHOULD BE THE TERRAIN
ACROSS SOUTHERN CA. MOISTURE (IN THE FORM OF PRECIPITABLE WATER
VALUES BETWEEN 1.25 AND 1.50 INCHES) AND MARGINAL INSTABILITY
SHOULD BE SUFFICIENT FOR SCATTERED TO LOCALLY BROKEN
CONVECTION...INITIALLY TIED TO THE TERRAIN. AS WAS THE CASE IN
AZ...ONE AND THREE HOUR FLASH FLOOD GUIDANCE VALUES ARE AS LOW AS
AN INCH...SO LOCAL FLASH FLOODING ISSUES ARE POSSIBLE. WITH THIS
IN MIND...A SEE TEXT AREA WAS PLACED OVER AZ INTO SOUTHERN CA.


...MID ATLANTIC/NORTHEAST...

MOISTURE AND INSTABILITY SURGING NORTHWARD AHEAD OF A FRONT
CROSSING THE MID ATLANTIC AND NORTHEAST WILL FUEL CONVECTION THAT
PRODUCES LOCALLY HEAVY RAINFALL DURING DAY 1. THE 00Z NAM AND ITS
RELATED GUIDANCE APPEARS TO BE TOO FAST WITH THE FRONT (PUSHED BY
A DEEPER AND FASTER MID LEVEL SHORT WAVE)...SO THIS WAS NOT USED
ON THE WPC QPF. THE WPC QPF WAS BASED ON A BLEND OF THE 00Z
GFS/12Z ECMWF...WHICH WERE CLOSER WITH THE FRONTAL TIMING AND
POSITION OF THE MOISTURE AND INSTABILITY AHEAD OF THE FRONT.

A SHORT WAVE TRACKING FROM CENTRAL CANADA EARLY THROUGH THE GREAT
LAKES PUSHES A COLD FRONT ACROSS THE MID ATLANTIC AND
NORTHEAST...MAINLY BETWEEN 30/18Z AND 31/06Z. AHEAD OF THE
FRONT...A LOW LEVEL 20 TO 30 KNOT FLOW TRANSPORTS PRECIPITABLE
WATER VALUES NEAR 2.00 INCHES (WHICH IS ABOUT TWO STANDARD
DEVIATIONS ABOVE THE MEAN) AND MODERATE TO LOCALLY STRONG
INSTABILITY INTO THE NORTHERN MID ATLANTIC AND NORTHEAST. THE
RESULTING CONVECTION BECOMES ORGANIZED IN A LINE AHEAD OF THE
FRONT. THIS SHOULD PRODUCE AN AXIS OF 0.50 TO 1.00 INCHES OF QPF
STRETCHING FROM NORTHERN MD ACROSS NJ/NY STATE INTO CENTRAL NEW
ENGLAND. THREE HOUR FLASH FLOOD GUIDANCE VALUES ARE FAIRLY
HIGH...SO WHILE LOCAL FLOODING ISSUES ARE POSSIBLE IN URBAN
AREA...ORGANIZED FLASH FLOODING IS NOT EXPECTED.


HAYES

GRAPHICS AVAILABLE ON THE WEB AT WWW.WPC.NCEP.NOAA.GOV

24HR QP VT 31/12Z
 0.01 470620 474621 477620 479621 482620 484620 488621 490621
      492622 494624 496626 498628 500630 501632 502629 501624
      501621 518663 519677 517685 513694 506701 502705 496703
      492702 490706 484712 479719 477732 475737 472741 467747
      461755 455762 448766 444770 438771 436773 431774 421776
      405784 399788 394793 382805 376813 370820 365827 360834
      353853 351863 349875 346882 340887 337884 334885 331895
      332909 332914 335917 342919 345921 347925 357941 359944
      361945 366943 370942 374943 377945 380949 385960 389968
      390973 390979 389991 387001 381008 379019 379026 380037
      383039 387037 393030 394026 395019 395011 395009 398009
      401012 402016 405026 407030 410035 413040 417042 420046
      423050 425058 424063 420063 412064 404062 399061 395062
      389062 386063 384064 382066 381073 379081 377084 375088
      372097 370102 369105 369108 373111 372115 370120 367123
      364132 360136 361141 360148 360151 361154 368160 373166
      376169 377173 375176 375182 380190 386197 388201 385202
      382202 379200 372196 363191 359188 357189 358192 359199
      358203 360208 363211 366216 367219 361219 358215 351209
      345203 344194 341186 341181 338179 336178 334174 320164
      317161 317158 319157 324157 325146 328143 333144 338151
      345156 347157 349156 352153 349145 344145 338144 335141
      339139 341134 338126 336123 332124 327131 324130 322126
      322120 321118 319118 314117 310115 304111 298106 290101
      283095 274092 266089 258085 250079 245076 242074 232063
      231054 233049 236046 239045 241046 248049 258053 264056
      281065 289069 293072 298072 304073 308076 311077 311079
      312084 317085 321084 320080 321078 323077 325076 323073
      324071 326071 330073 334072 337069 339066 340061 336059
      332058 327057 328055 335057 339057 342055 344051 345043
      342041 340038 336030 335023 330023 329017 329013 332010
      344993 348978
 0.01 348978 347971 344965 340953 338951 335950 333951 329956
      325960 319963 314964 308964 298969 294969 290970 287970
      285969 280965 276960 272958 268953 263942 257929 255923
      255913 256907 256899 261888 265882 265876 264858 264851
      263843 260828 257812 257807 252802 253798 255792 255778
      262766 262763 265761 270756 274753 280749 284746 288741
      291737 295733 301731 303729 310728 315730 323729 333723
      340719 346715 355706 359702 364698 374691 381686 387684
      392680 400678 408669 412663 416659 425648 429643 435637
      447628
 0.01 558051 558039 557028 556019 554012 549994 546986 542978
      537962 533944 528930 519915 515910 512903 508897 506888
      502872 501865 499862 498857 495855 492855 490858 489861
      488866 486866 484864 480860 471848 462836 458832 455832
      455838 456842 458847 458852 456854 457867 459874 463881
      468888 474900 477906 478910 475909 472909 470907 464903
      461903 460907 463915 466921 465924 466928 474939 478943
      482949 485948 486944 489944 491947 493955 491958 487957
      481957 479962 479967 480972 482980 485987 490988 492985
      497970 499968 502970 505975 508983 512989 518996 521003
      534029 541043 545049 549055 556056 558051
 0.01 364764 353757 347754 343754 340755 333768 325780 321786
      319789 319793 316801 316805 315808 317810 323807 331802
      343796 349792 352790 354789 353786 353780 357774 361769
      364764
 0.25 533994 533986 533981 530968 522944 518935 513925 503908
      498899 492892 488891 486894 489907 491919 492926 494932
      498942 502952 507962 512972 521989 528996 531998 533994
 0.25 510658 507650 505646 502644 495644 488646 481651 476652
      473652 465649 459644 452649 447656 438667 439672 444671
      453667 462666 463671 465676 466680 464683 462686 458689
      453693 448700 440706 433711 427716 421718 422714 425711
      428704 439694 441686 441682 440680 436679 433682 430686
      427695 423701 417707 413713 409719 403734 398742 394750
      392754 389758 386759 384757 381748 380745 382741 391727
      396720 399717 400711 395711 393713 388720 380732 376739
      376745 379748 371765 370769 371773 381772 387775 389777
      393776 424763 428763 432761 437756 447746 452740 456732
      460722 465716 485692 488685 493677 497675 500675 504673
      507671 510665 510658
 0.25 413703 414701 414699 412697 410698 409700 407702 406703
      406704 404706 403708 402711 403712 404713 405713 406712
      407712 409711 410709 412707 412706 413704 413703
 0.25 369187 369185 368184 366183 365182 363184 362184 364186
      365187 366187 367188 369187
 0.25 380988 380983 379976 376972 374967 373962 369957 364959
      359957 356961 355967 355976 353991 352998 349004 347008
      347014 348019 347027 348031 347037 355041 354045 352051
      350055 348061 347063 348065 352069 347081 343081 338079
      333078 330079 329081 326083 328088 330094 329097 325098
      323101 321104 321108 323110 326111 329107 332105 335105
      337106 338109 344116 349118 352122 355120 356117 352114
      351112 351108 352103 349101 346098 347094 350096 355098
      358097 362094 364092 365089 364087 361085 358080 360075
      365073 369071 373070 375069 375066 371062 366060 366052
      363049 363045 365043 369041 371037 373023 374012 376998
      379992 380988
 0.25 345169 344169 344167 343165 342164 342163 341162 340160
      339161 339163 338165 336165 334166 333167 334168 335169
      337170 339171 340172 342172 344171 344170 345169
 0.25 353830 353828 353827 352828 351829 349830 349831 348832
      347833 347836 347838 347840 348841 350840 351840 352837
      352835 353833 353831 353830
 0.25 328746 327742 326740 323740 317740 312742 301746 290751
      283756 278763 276767 274772 273785 273789 272793 270795
      266797 264800 265805 265809 267819 275867 275872 274879
      271887 269898 268905 269913 272922 277930 281933 285934
      290931 294926 300921 303918 305914 309910 311905 312892
      314880 315869 315841 314834 313827 312823 309819 303812
      300808 299804 299800 303792 308785 314777 321769 327760
      328752 328746
 0.25 319108 319106 317103 316102 314101 312101 312103 312105
      313107 315109 317109 319108 319108
 0.25 321095 321093 320092 318091 317092 316092 316094 317095
      318096 320097 321095
 0.25 311090 299080 285075 279073 271069 266065 257063 252059
      246056 242055 240057 241060 244063 255071 260076 266080
      279086 287088 295090 302091 306091 311090
 0.50 523978 523968 522957 519947 516939 512933 507928 504928
      503934 505944 508952 511960 515968 518974 523978 523978
 0.50 479688 477686 478683 476682 474688 468691 462694 458698
      455703 455707 457708 464706 471704 474700 478694 479688
 0.50 443713 443710 441710 437713 431718 423725 416731 411737
      404742 404746 408748 414743 421737 429732 434725 440718
      443713
 0.50 432749 431747 429747 429748 427749 426750 424751 423753
      422754 422756 423757 425757 426757 428755 430753 430752
      431751 432749
 0.50 375990 375983 371976 368971 366974 364974 361969 357976
      357985 358996 356009 360023 357029 356032 357038 358040
      360042 366037 368031 369021 370012 371003 375990
 0.50 362069 363065 361063 360060 361057 361055 359053 357053
      354055 353057 353062 354064 355067 356070 360071 362069
 0.50 354084 354082 352082 351084 352085 353085 354084
 0.50 355075 354074 353074 352075 352077 354077 355075
 0.50 350088 351085 348084 344086 339087 336083 332080 332084
      334088 338091 336095 336099 338101 341101 343102 344098
      343094 344089 350088 350088
 0.50 345114 347112 347110 346107 346106 344105 344107 343109
      343111 344112 345114 345114
 0.50 328105 329103 329101 329100 327099 326100 326102 325103
      324104 323106 322106 323106 324109 326109 328107 328106
      328105
 0.50 321758 320751 317748 311748 305750 294754 290755 286760
      281767 280772 280780 283784 287787 290787 296784 305779
      311773 318765 321758
 0.50 309854 309836 309826 305820 300816 295813 284806 279805
      273802 271801 270804 272806 275807 277814 281819 278823
      276830 278832 278837 279841 278848 279856 280865 279873
      278880 275888 273895 273902 273908 276917 279922 284925
      288922 292915 298913 302909 306905 304897 304892 306885
      310869 309854
 0.50 301086 301084 297082 296081 292080 288079 287078 283078
      279077 278080 281082 283083 286085 288085 291086 295087
      299087 301086
 0.50 273075 272075 271074 270075 272076 273075
 1.00 370987 369986 368987 366987 366990 367990 368990 369989
      370987
 1.00 314762 314760 313758 313757 312758 311758 310759 308760
      307761 306761 304762 303764 301766 301768 302768 303769
      305769 307769 309768 311767 312765 313764 314762 314762
 1.00 304852 304842 303831 302827 299827 297836 295842 294851
      295859 293866 290874 285878 281883 279892 279901 280906
      282910 286907 289900 290892 292889 296887 299881 302874
      303871 303867 302857 304852
 1.50 286893 286891 286889 285888 284889 283889 284891 283894
      283896 283898 283900 283902 284903 285902 285900 285898
      286896 286895 286893

$$





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