Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 310651
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
250 AM EDT FRI JUL 31 2015


PRELIM DAY 1 QPF DISCUSSION
VALID JUL 31/1200 UTC THRU AUG 01/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1


...SOUTHWEST/SOUTHERN PLAINS...

MONSOONAL MOISTURE CONTINUES TO POUR INTO THE SOUTHWEST
STATES...AND SOME OF THE DEEP MOISTURE IS BEING DIVERTED INTO THE
SOUTHERN PLAINS ALONG AN FRONTAL BOUNDARY. THE DEEP
MOISTURE...COMBINED WITH MARGINAL TO MODERATE INSTABILITY...COULD
RESULT IN ORGANIZED CONVECTION WHICH PRODUCES HEAVY TO EXCESSIVE
RAINFALL ACROSS PORTIONS OF THE REGION DURING DAY 1. THERE WAS
GENERALLY GOOD MODEL AGREEMENT WITH THE PLACEMENT OF SURFACE
BOUNDARY AND THE DEPTH OF THE MOISTURE...SO THE WPC QPF WAS BASED
MAINLY ON A BLEND OF THE 00Z NAM/GFS. THE 00Z WRF ARW AND 00Z
REGIONAL GEM WERE USED TO HELP DEFINE THE HEAVY RAIN AXIS
STRETCHING FROM NORTHEAST NM ACROSS NORTH TX.

CONVECTION CONTINUES ACROSS EAST CENTRAL NM EARLY THIS
MORNING...AS DEEP MOISTURE (WITH PRECIPITABLE WATER VALUES NEAR
1.25 INCHES) FEEDS THE ACTIVITY. THERE IS A MULTI HIGH RESOLUTION
MODEL SIGNATURE THAT AN MCV WILL BE EJECTED FROM THIS
ACTIVITY...WHICH CROSSES NORTHEAST NM ACROSS NORTH TX INTO THE
WESTERN OK PANHANDLE. THE MCV ENCOUNTERS DEEP MOISTURE AND
MODERATE INSTABILITY ALONG EN ELEVATED BOUNDARY EXTENDING ACROSS
NORTHEAST NM AND NORTH TX...WHERE MODEL SOUNDINGS SHOWED MODERATE
TO LOCALLY STRONG INSTABILITY DEVELOPING AFTER 31/18Z.

THE LOW LEVEL FLOW INCREASES ACROSS WEST TX INTO WESTERN OK AND
WESTERN KS AFTER 01/00Z...THOUGH THERE IS SOME SPREAD CONCERNING
JUST HOW STRONG IT GETS. ASSUMING A 20 KNOT LOW LEVEL INFLOW INTO
NORTH TX...A SMALL MCS COULD DEVELOP AFTER 01/06Z THERE...AND
CONTINUE EAST SOUTHEAST ALONG THE DIFLUENT THICKNESS PATTERN INTO
SOUTH CENTRAL OK BEFORE 01/12Z. THE MOISTURE IS DEEP ENOUGH FOR
HIGH RAINFALL RATES WITH THE MCS...SO AN AREA OF 1.50 TO 2.00
INCHES OF QPF WAS PLACED OVER NORTH TX AND NEARBY WESTERN OK.
WHILE THE QPF VALUES ARE BELOW THE THREE HOUR FLASH FLOOD GUIDANCE
VALUES...THE POTENTIAL FOR HIGH RAINFALL RATES SUGGESTS THE
POTENTIAL FOR FLASH FLOODING. ACCORDINGLY...A SLIGHT RISK WAS
EXTENDED FROM NORTHEAST NM (WITH THE MCV) INTO NORTH TX AND A
PORTION OF WESTERN OK.

FURTHER WEST...THE MONSOONAL FLOW CONTINUES ACROSS AZ/WESTERN NM.
THERE IS A MULTI MODEL SIGNAL THAT A SHORT WAVE IN THE MID LEVEL
SOUTHERLY FLOW UNDER THE RIDGE COULD CROSS AZ DURING THE SECOND
HALF OF THE PERIOD. THAT COULD ENHANCE LIFT ACROSS EASTERN
AZ/WESTERN NM...ALLOWING CONVECTION TO FORM OUTSIDE OF THE
TERRAIN. THE HIGH MOISTURE CONTENT AIR (WITH PRECIPITABLE WATER
VALUES TOPPING OUT NEAR 1.75 INCHES IN SOUTHWEST AZ) COULD ALLOW
FOR LOCALLY HEAVY RAINFALL WITH THE CONVECTION. HOWEVER...AT THIS
POINT...IT IS UNCLEAR JUST HOW WIDESPREAD THE HEAVIER RAINFALL
WILL BE...SO FOR NOW NO SLIGHT RISK AREA WAS ASSIGNED.


...GULF COAST/SOUTHEAST...

A SLOWING FRONTAL BOUNDARY BECOMES NEARLY STATIONARY AS IT
STRETCHES FROM THE MID ATLANTIC COAST INTO THE GULF COAST REGION
DURING DAY 1. ALONG AND HEAD OF THE FRONT...DEEP MOISTURE AND
STRONG INSTABILITY WILL PRODUCE CONVECTION WITH THE POTENTIAL FOR
HEAVY RAIN EXTENDING ACROSS PORTIONS OF THE SOUTHEAST AND FL.
THERE WAS GENERALLY DECENT MODEL AGREEMENT WITH RESPECT TO THE
TIMING OF THE FRONT (THOUGH THE 00Z NAM MAY BE A TAD FAST...
ESPECIALLY ACROSS THE SOUTHEAST COAST). THE WPC QPF WAS BASED
PRIMARILY ON A BLEND OF THE 00Z GFS/12Z ECMWF...WITH SOME SUPPORT
FROM THE 00Z REGIONAL GEM.

A DEEP MOISTURE SOURCE (WITH PRECIPITABLE WATER VALUES NEAR 2.25
INCHES EXTENDING FROM COASTAL SC ACROSS SOUTHERN GA THROUGH
NORTHERN FL) REMAINS IN PLACE JUST AHEAD OF THE SLOW ADVANCING
FRONT AS IT CROSSES THE SOUTHEAST STATES. MODEL SOUNDINGS SUGGEST
THAT THE BEST INSTABILITY SHOULD LIE JUST AHEAD OF THE FRONT AS
WELL...WITH MODERATE INSTABILITY INDICATED. THE RESULTANT
CONVECTION SHOULD MOVE FROM SOUTHWEST TO NORTHEAST AHEAD OF THE
FRONT...BUT THE MID LEVEL FLOW IS FAIRLY WEAK...AND SLOW CELL
MOTIONS ARE EXPECTED. THIS SHOULD RESULT IN AN AREA OF 0.75 TO
1.25 INCHES OF QPF ACROSS THE FL BIG BEND REGION...EXTENDING INTO
THE WESTERN FL PANHANDLE.

LOCALLY HIGHER AMOUNTS ARE POSSIBLE IN THE VICINITY OF SLOW MOTION
CELLS OR CLUSTERS...AND HIGHER RESOLUTION GUIDANCE LIKE THE 00Z
REGIONAL GEM AND THE 00Z WRF ARW SUGGEST AMOUNTS OF 3 TO 5 INCHES
ARE POSSIBLE ON THE FL WEST COAST...SOUTH OF THE BIG BEND. ONE AND
THREE HOUR FLASH FLOOD GUIDANCE VALUES ARE GENERALLY ABOVE 3.00
INCHES...SO AT THIS POINT ORGANIZED FLASH FLOODING DOES NOT APPEAR
LIKELY.


...UPPER GREAT LAKES...

SHORT WAVES RIDING THROUGH THE FAST MID LEVEL FLOW ACROSS THE
UPPER GREAT LAKES TAKE ADVANTAGE OF THE AVAILABLE MOISTURE AND
LIMITED INSTABILITY TO PRODUCE QPF DURING DAY 1. FOR THE MOST
PART...THERE WAS GOOD MODEL AGREEMENT WITH THE OVERALL
PATTERN...BUT THERE WERE SOME TIMING DIFFERENCES WITH THE SHORT
WAVES (WHICH IS TO BE EXPECTED IN A FAST FLOW). IN AN ATTEMPT TO
MITIGATE SOME OF THE TIMING DIFFERENCES...THE WPC QPF WAS BASED ON
A BLEND OF THE 00Z GFS/12Z ECMWF.

THE AIRMASS IN PLACED ACROSS THE GREAT LAKES INITIALLY IS FAIRLY
DRY AND GENERALLY STABLE. HOWEVER...MID LEVEL LAPSE RATES STEEPEN
WITH THE APPROACH OF EACH SHORT WAVE...ALLOWING THE COLUMN TO
BECOME MARGINALLY UNSTABLE NEAR 01/00Z ACROSS NORTHERNMOST WI AND
THE UP OF MI. THE LOW TOPPED CONVECTION WILL TAP 0.75 INCH
PRECIPITABLE WATER AIR TO PRODUCE A STRIPE OF 0.10 TO 0.25 INCHES
OF QPF ACROSS THE ARROWHEAD OF MN AND THE UP OF MI.


...CENTRAL PLAINS/MIDWEST...

MOISTURE AND INSTABILITY SIPHONED FROM SOUTHERN PLAINS ON LOW
LEVEL SOUTHERLY FLOW INTERACTS WITH SHORT WAVES IN THE FAST MID
LEVEL FLOW TO PRODUCE A SWATH OF CONVECTION ACROSS THE
REGION...MAINLY DURING THE AFTERNOON AND EVENING HOURS. THERE WAS
GOOD MODEL AGREEMENT WITH THE OVERALL SYNOPTIC SETUP...BUT THERE
WAS SOME SPREAD CONCERNING JUST HOW MUCH MOISTURE/INSTABILITY
BECOMES INVOLVED IN THE CONVECTIVE DEVELOPMENT. THIS IS RESULTING
IN DIFFERENCES IN THE MAXIMUM QPF IN THE AXIS ACROSS ME INTO
IA/NORTHERN MO. THE 12Z ECMWF APPEARS TO BE INJECTING TOO MUCH
MUCH MOISTURE AND INSTABILITY INTO THE FLOW FROM THE SOUTHERN
PLAINS...AND CONSEQUENTLY PRODUCES TOO MUCH QPF. THE WPC QPF WAS
BASED MORE ON A BLEND OF THE
00Z NAM/GFS...WHICH HAS THE SUPPORT OF THE 00Z WRF ARW AND THE 00Z
REGIONAL GEM.

MODEL SOUNDINGS SHOWED MODERATE INSTABILITY AND PRECIPITABLE WATER
VALUES NEAR 1.25 INCHES DURING THE AFTERNOON AND EVENING HOURS
STRETCHING FROM EASTERN NE ACROSS SOUTHWEST IA AND NORTHWEST MO.
THE LIFT FROM THE SHORT WAVES IS RATHER WEAK...BUT SHOULD BE
ENOUGH TO ALLOW STRIPES OF CONVECTION TO DEVELOP...AIDED BY
HEATING OF THE DAY. THE BEST CONVECTION SHOULD CROSS SOUTHEAST NE
INTO NORTHWEST MO...WHERE A STRIPE OF 0.10 TO 0.25 INCHES OF QPF
WAS PLACED. THE SPEED OF MOVEMENT OF THE LOW TOPPED CONVECTION
SHOULD BE BEST FAST ENOUGH TO PRECLUDE MUCH HIGHER QPF AMOUNTS.

HAYES

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

24HR QP VT 01/12Z
 0.01 450627 451633 454630 455633 455636 458638 462636 467634
      469631 478627 485628 493632 498642 500658 499672 497683
      495692 492697 487699 484696 482695 479695 476699 474702
      476706 479709 481713 481720 481725 481728 482730 485732
      490739 492741 493747 494763 498772 500779 500785 500793
      499799 496813 495825 493835 491840 493848 500853 504860
      505866 506872 505878 504886 506892 539963 543973 544980
      544990 537995 537997 534999 530000 520000 516999 512995
      508991 506986 500978 496972 491965 482952 481947 477942
      474932 472927 469925 467921 465914 465905 463899 464894
      461888 447878 445872 446867 446858 447851 449847 453844
      453837 453830 452817 452811 452807 454796 456788 458782
      459779 457776 451782 445789 440799 436809 432820 427829
      423834 418835 412835 410832 409817 416800 421783 423773
      422768 423763 426753 429744 433735 436729 439725 462688
      463686 461682 458680 450677 449672 451671 451665 449657
      446652 440650 436650 432652 427658 421667 416674 410683
      406691 402699 396708 383725 380729 378734 375742 367762
      364769 359775 355781 352789 348796 345806 344813 343818
      340829 337838 332848 330851 328857 321866 319870 317874
      314882 304899 299906 298915 296924 296929 293932 291936
      288941 282946 278948 273948 266948 261950 256950 252948
      247939 244932 244921 245908 245901 247895 250885 252875
      254855 256848 259840 260835 260829 258825 255823 254820
      255815 255810 254805 253800 254794 256782 259777 261772
      267765 273759 279751 284745 291740 293737 299736 304734
      308731
 0.01 308731 312725 317718 321713 326705 330700 335692 339687
      346681 351677 359672 366667 369665 373666 379669 383671
      382674 387680 388683 389681 391678 396671 400664 410650
      419638
 0.01 466652 466649 466647 466644 465642 463641 462642 460642
      459643 458644 458647 459648 460649 461650 462651 463652
      464652 465653 466652
 0.01 467664 466662 465661 464660 463659 462658 461657 460656
      459655 458655 457654 455654 453654 453656 453658 453661
      454663 455665 455668 457669 459669 461669 462668 464668
      466666 467664
 0.01 481004 480994 478989 475983 472978 469973 467971 464971
      463974 464979 466984 469990 472995 474002 478006 481004
 0.01 429044 429037 428031 428025 425008 424999 424991 429995
      431993 432987 431980 428971 425964 423956 418940 415933
      413930 410927 405924 400924 399915 398910 396906 392904
      385904 383904 382906 382911 384915 386920 390926 393934
      394939 394945 395981 396991 396000 397005 399007 402009
      406010 410010 412019 414026 417036 422044 427046 429044
 0.01 398206 394200 389198 387194 387189 386185 383181 379179
      372180 364175 361169 359167 360172 358174 355171 355173
      356176 359179 358182 355182 352183 351187 359186 362189
      367191 372195 380201 379202 375200 373201 372205 375204
      379206 386211 390212 393210 398206
 0.01 412915 410901 406891 403886 401880 397869 392860 388858
      385859 385861 385868 387874 392884 396894 401906 403910
      407915 409917 412915
 0.01 406061 407055 404051 397048 393046 391042 384036 386021
      388020 390017 390012 385006 378000 377995 379992 382986
      371976 367967 364963 361958 353953 350952 345951 339954
      337958 337963 339968 338970 331975 328978 325983 322986
      322990 325991 330992 331995 329997 327999 327003 328009
      328015 328020 330024 334030 340037 341041 340043 335044
      331045 325047 325053 327057 330066 328072 327075 325079
      323082 315085 309084 305082 301079 296076 292075 286074
      280073 275071 267067 258067 256069 255074 255081 256085
      261092 266099 274106 286118 297126 314135 322139 332136
      347134 346140 348143 351143 352148 355147 358147 360150
      359154 360156 362159 379169 379166 375162 369160 367159
      366156 370153 367151 364153 359148 360142 359140 355140
      353140 352137 354134 357134 361137 364140 368140 373137
      376134 378131 379126 379122 381120 387115 389110 388106
      383096 383093 385093 385090 383088 383084 386079 392073
      396072 400067 402062 406061
 0.01 345180 345178 344175 345173 345171 344170 343169 343166
      341167 339167 338165 337167 337168 339170 341171 342173
      343175 343177 343180 345180 345180
 0.01 312981 312973 312966 309961 305956 296951 293950 290952
      284954 280958 280966 284977 292985 292993 293002 296006
      300005 306004 309999 311992 311983 312981
 0.25 529970 529965 527962 524955 521948 518942 510929 503919
      495909 492907 489909 488913 489917 492923 496929 503942
      510955 517965 522970 524971 528971 529970
 0.25 485760 483755 479756 477760 471772 466787 464793 464804
      466814 468824 470830 474837 476838 479837 480828 479810
      478799 478790 480781 483774 485768 485760
 0.25 407973 407970 407968 407966 407963 407962 406961 405959
      404959 403958 403959 403961 402963 402966 403968 403969
      404970 405972 406973 407973 407973
 0.25 381195 379192 378191 376189 373187 370185 368184 364184
      367187 369188 372190 374192 377194 379195 381195
 0.25 377691 378686 376682 375679 373677 370676 365677 359682
      353689 350695 343710 338721 335728 331734 327740 321745
      316750 308754 296759 289762 282766 277771 273776 272780
      271785 273790 275793 279797 281801 280809 276817 271822
      269825 268831 272837 273842 273847 271861 265875 260891
      254905 252912 251918 252926 252931 254936 255940 258941
      262943 266943 274939 280935 284930 286924 288917 290908
      291899 294890 302887 307883 312872 316865 318857 324843
      330826 335814 338798 338787 341780 349767 370708 377691
 0.25 378098 378096 378095 376096 376097 376098 378099 378098
 0.25 381056 381051 379049 376050 371048 370044 372039 376030
      378022 375013 366996 361992 360987 361983 358976 346975
      343977 343982 342986 341989 343991 346993 348997 347002
      345008 344017 347026 350035 352039 352046 353049 351052
      347060 346064 348067 350072 347075 343075 341072 339072
      335075 331076 329078 330081 329090 332091 333094 332097
      335101 341102 344098 346093 351094 358097 363103 365092
      358080 363080 363076 365073 369071 372068 375066 375063
      375060 377059 381056
 0.25 373111 373109 371107 371106 370105 368105 367106 368107
      369108 369109 371111 373111 373111
 0.25 346109 345107 344106 344105 343103 341104 340106 340109
      340110 342110 344111 346109
 0.25 330101 329098 328098 327098 325100 325101 324102 325104
      326105 327105 328103 330101
 0.25 319108 319106 319104 318102 316102 314103 312103 310104
      309104 310106 310107 311109 313110 314112 315112 316112
      317111 318110 319108 319108
 0.25 320095 319093 318092 317093 316094 316095 318097 320095
 0.25 301103 301100 300097 296093 291090 287087 282084 279083
      275083 271087 274094 279096 285099 290101 295103 301103
 0.25 296960 296959 294958 292957 290957 289958 288959 287960
      288962 288963 289964 290965 292965 293964 294964 295962
      296961 296960
 0.50 374692 374687 372684 366682 358696 343721 338734 335741
      330747 326751 320756 313760 305763 290767 285772 284776
      283781 287787 292791 303800 307801 311800 316795 327784
      330779 335774 345762 348757 351750 357734 361720 368705
      374692
 0.50 371032 373026 374019 372013 369009 363003 355996 353993
      352987 351982 348985 347988 348990 349994 351000 351007
      347015 347020 348025 356044 356047 354051 352056 352058
      355060 356064 354069 352074 353076 356075 357072 361069
      364065 369063 367054 368053 367049 366047 367043 371032
 0.50 352084 353082 352081 350081 352084 352084
 0.50 354062 353062 352061 351062 352063 353062 354062
 0.50 342098 343096 342094 342093 340091 339093 338094 337095
      336096 336097 338098 340099 342098 342098
 0.50 341089 341087 341085 342083 341082 339081 338081 337082
      336082 334084 333086 335088 337089 339090 341089 341089
 0.50 342076 342075 340074 338076 340077 342077 342076
 0.50 332079 333077 332077 332079 332079
 0.50 312865 312862 313860 311859 310860 310861 308862 307863
      306864 305865 305867 304869 304871 304874 304876 305877
      307876 307875 308874 309873 309871 310870 310869 311867
      312865 312865
 0.50 305844 306837 302831 296826 293821 292816 290813 288814
      284817 278826 276830 277834 280846 282860 285863 289861
      298856 304848 305844
 0.50 295809 296807 295805 294803 292801 290800 289801 289802
      287804 287806 287808 288810 289812 291812 293811 295811
      295809
 0.50 287883 286876 283870 277873 273878 270882 267888 262901
      255913 255929 256936 261939 267939 273935 278932 282927
      284920 285912 285893 287883
 1.00 360707 357707 355712 353715 351720 350725 348729 347734
      349735 351733 352728 354724 356720 357716 358712 360707
 1.00 370023 370016 365012 360010 356011 354013 352019 353024
      355030 356038 360043 361043 364038 368033 370025 370023
 1.00 340751 341747 338746 334752 328761 326766 322769 315771
      309771 303772 299776 299781 305784 307790 311789 316786
      321782 323778 328773 334763 339753 340751
 1.00 301840 301838 299836 296834 293832 291832 288832 287835
      288837 289841 290843 292846 296845 298844 300842 301840
 1.00 279919 280908 279903 277901 274899 269899 267901 265905
      262911 259918 258927 259932 261934 265934 269933 274929
      277927 278923 279919
 1.50 368023 368020 367017 365015 361014 360013 357014 356016
      355020 355025 356027 359029 361030 363028 364027 367025
      368023
 1.50 276923 276917 275910 273906 270906 267909 264912 262915
      260919 261925 261929 266931 270928 274925 276923
 2.00 273921 273917 272913 270911 268913 265915 264917 262919
      262923 263925 264927 266927 269925 271923 273921

$$




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