Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 271807
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
207 PM EDT SAT MAY 27 2017


PRELIM DAY 1 QPF DISCUSSION
VALID MAY 28/0000 UTC THRU MAY 29/0000 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...

...SOUTHERN PLAINS / MID MISSISSIPPI VALLEY / TENNESSEE VALLEY...

IT IS THE RIGHT TIME OF YEAR FOR IT...BUT WE ARE IN FAIRLY RARE
PARAMETER SPACE ON DAY 1 WITH STEEP LAPSE RATES AND AMPLE MOISTURE
LEADING TO LEGITIMATE SFC-BASED CAPES OF 5000-PLUS J/KG...COUPLED
WITH DEEP LAYER SHEAR OF 40 TO 50 KNOTS OVER THE SOUTHERN PLAINS
AND AREAS FARTHER EAST. DEEP LAYER FORCING IS NOT QUITE SO FOCUSED
UNTIL THE POSITIVELY TILTED TROUGH IN THE ROCKIES/PLAINS SWINGS
AROUND SATURDAY NIGHT AND SUNDAY TO BECOME MORE NEUTRALLY
TILTED...SPURRING A SURFACE LOW TO TAKE SHAPE AND LIFT TOWARD THE
GREAT LAKES. IN THE ABSENCE OF STRONG DEEP LAYER FORCING...EXPECT
CONVECTION ORGANIZED ON THE MESO AND STORM SCALES THIS AFTERNOON
AND EARLY EVENING. GREATER ORGANIZATION AND COVERAGE IS EXPECTED
IN KS/MO...ESPECIALLY SOUTHERN MO PER LATEST GUIDANCE...ALONG THE
MID LEVEL GRADIENTS / NORTHERN EDGE OF THE CAPPED WARM SECTOR.
OTHER ISOLATED OR SCATTERED INITIATION WILL LIKELY OCCUR DOWN THE
DRYLINE INTO OK/TX. ACTIVITY THAT DOES FORM WILL FIND ITSELF
WITHIN A LARGE POOL OF SFC-BASED INSTABILITY NO MATTER WHICH
DIRECTION IT PROPAGATES...BUT GIVEN THE PREVAILING FLOW IT IS MOST
LIKELY THAT ONE OR MORE CONVECTIVE CLUSTERS OR SMALL MESOSCALE
SYSTEMS WILL TRACK OUT OF KS/MO TOWARD ADJACENT NORTHEAST ARKANSAS
AND PARTS OF SURROUNDING STATES. SUPERCELLS AND CLUSTERS
INITIATING ALONG THE DRYLINE WILL ADVANCE GENERALLY EASTWARD...AND
MAY BE SUPPORTED THROUGH THE NIGHT...REACHING PARTS OF ARKANSAS OR
FAR NORTHERN LOUISIANA. THE BACKGROUND SYNOPTIC LIFT WILL BECOME
MORE FAVORABLE THROUGH TIME...SUCH THAT THE THREAT OF ORGANIZED
HEAVY RAIN WILL LIKELY PERSIST THROUGHOUT THE NIGHT GIVEN STRONG
INSTABILITY AND SUSTAINED INFLOW.

PARTS OF SOUTHERN MISSOURI WERE UPGRADED FOR A MODERATE RISK OF
EXCESSIVE RAINFALL...OWING TO GREATER CONFIDENCE IN THE NEAR TERM.
OTHER AREAS FARTHER SOUTH/EAST MAY EXPERIENCE AN INCREASED RISK AS
WELL...ALTHOUGH THE DETAILS WERE STILL UNCLEAR AS OF 18Z...AND
SLIGHT RISK WAS MAINTAINED PER COORDINATION WITH LOCAL OFFICES.

THE INHERITED WPC QPF HAD LEANED IN THE DIRECTION OF THE 00Z ECMWF
AND 00Z WRF-ARW. OVER THE LONG HAUL THIS APPROACH STILL APPEARS
SUPPORTED...THOUGH IN THE EARLY PORTION OF DAY 1 WE MADE SOME
ADJUSTMENTS TOWARD THE HRRR AND THE OBSERVATIONAL TRENDS. WE THEN
INCORPORATED ABOUT 20 PERCENT OF THE 12Z GFS IN OUR BLENDS AT
LATER TIME STEPS TO NUDGE THE QPF SWATHS BACK NORTH AND EAST A
BIT...GETTING CLOSER TO THE WRF-ARW / NAM CONUS NEST / NSSL WRF
CONSENSUS. OVERALL...THIS KEPT PRETTY GOOD CONTINUITY...WHILE
ADJUSTING THE QPF MAXIMUM IN NORTHERN ARKANSAS UP INTO MORE OF
SOUTHERN MISSOURI AND OVER INTO WESTERN TENNESSEE...A MOVE THAT
APPEARED TO HAVE SUPPORT FROM THOSE LOCAL OFFICES. AS A
CAVEAT...HOWEVER...IN AN ATMOSPHERE THIS UNSTABLE THERE MAY BE
SUDDEN UPSCALE GROWTH AND DEVIANT MOTION THAT COULD WREAK HAVOC
WITH PRECIPITATION AMOUNTS ON LOCAL SCALES.


...MIDWEST / GREAT LAKES TO THE MID ATLANTIC...

BROAD ZONES OF FAVORABLE INSTABILITY AND ASCENT WILL EXIST ALONG A
QUASI-STATIONARY FRONT IN THE APPALACHIANS / MID ATLANTIC...AND
ALONG THE TRACK OF THE DEVELOPING SURFACE LOW AND SWEEPING FRONTAL
STRUCTURE OVER THE WESTERN OHIO VALLEY...INCLUDING INVERTED
TROUGHING UP THROUGH THE GREAT LAKES. PRECIPITATION WILL BE
GENERALLY LESS INTENSE WHEN COMPARED TO THE ENVIRONMENT OF STRONG
INSTABILITY OVER THE SOUTHERN PLAINS AND TENNESSEE VALLEY...BUT
WIDESPREAD ACCUMULATIONS OF AT LEAST 0.25 INCHES ARE
EXPECTED...WITH PLENTY OF POTENTIAL TO SEE AREAL AVERAGE SWATHS
APPROACHING 0.75 INCHES...AND LOCAL DOWNPOURS HEAVIER THAN THAT.
FOR THESE AREAS WPC BEGAN WITH A 40/20/20/20 BLEND OF PREVIOUS WCP
/ 12Z GFS / THE WPC IN-HOUSE ENSEMBLE / SSEO MEAN.


...ELSEWHERE...

COLORADO...A CONVECTIVE SYSTEM CONSISTING OF SHALLOW BUT
NONETHELESS ORGANIZED THUNDERSTORMS IS REPRESENTED IN MOST OF THE
NUMERICAL GUIDANCE...EXPECTED ACROSS EASTERN COLORADO THIS
AFTERNOON WITH THE BASE OF THE UPPER TROUGH PASSING THROUGH.
THOUGH SURFACE WINDS WERE ALREADY TURNING NORTHERLY THERE WILL
STILL BE RESPECTABLE PRECIPITABLE WATER VALUES OVER A HALF
INCH...SUCH THAT SOME SPOTTY QUARTER TO HALF INCH PRECIP TOTALS
ARE POSSIBLE. THE SYSTEM ITSELF MAY SURVIVE AS IT RACES TOWARD THE
OK PANHANDLE / NORTHWEST OK...BUT WITH DIMINISHING PRECIPITATION
AS IT ENCOUNTERS A DRIER ENVIRONMENT.

NORTH DAKOTA / MINNESOTA...STEEP LAPSE RATES AND COLD TEMPERATURES
ALOFT WILL MAINTAIN A SHOWERY REGIME FAVORABLE FOR SHALLOW
CONVECTION. PRECIPITATION MAY BE MORE PERSISTENT OVER TIME ACROSS
NORTHERN MN...WHERE HEIGHTS WILL CONTINUE TO FALL AND AN UPPER LOW
BECOMES BETTER DEFINED WITH THE PLAINS/MIDWEST SHORTWAVE ROTATING
UNDERNEATH IT.

IN THE WEST...LOOSE COVERAGE OF SHALLOW CONVECTIVE SHOWERS WITHIN
NORTHWEST FLOW.

BURKE


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


24HR QP VT 29/00Z
 0.01 526172 525164 527157 525151 522147 519141 516138 507135
      498130 492120 488111 487108 489109 493112 497116 502116
      505111 509113 513124 516129 518131 519128 522124 523113
      522106 520099 515092 504086 500084 497084 495085 489085
      486080 481078 478079 477081 476087 477094 478101 476103
      474099 472093 469090 461083 457081 454080 453076 451071
      447067 443064 438064 438070 441074 444077 449082 452087
      451091 449093 438093 439099 439105 442109 444111 447111
      453112 458112 462116 465122 469130 473134 477137 482140
      485146 487152 492153 500152 506153 510157 517168 521172
      526172
 0.01 502202 501198 497198 494199 490202 487204 483206 481208
      480211 482212 486210 489208 493207 497205 499203 502202
 0.01 514905 513892 510885 506880 499875 494876 488881 484886
      478890 472895 467900 460915 460919 458923 455925 454930
      452937 452947 456955 457959 458962 457964 457968 455971
      458979 457982 456989 457999 458008 461016 466023 469024
      470020 475004 479994 483996 486998 497003 500001 502998
      504993 504988 501981 504972 505967 506962 505951 504945
      506941 509934 510926 511917 514905
 0.01 493815 492807 491798 490793 488792 486791 482791 477793
      474798 470803 467808 463811 457812 447809 444809 442807
      438801 433790 427779 424777 418773 411765 406764 399765
      397762 397757 396749 395743 392736 384722 375711 360699
      348701 340706 337714 337725 338739 341768 337782 338787
      343788 342794 339805 338811 339819 342823 343828 342831
      332837 327845 324851 323857 323866 325874 330886 330890
      329893 327898 322908 321924 317935 315940 312945 307955
      302967 296978 290986 283993 276999 268006 259012 257018
      256026 260031 265034 271036 276039 287037 292036 297034
      303023 307020 311017 313013 315005 317001 319994 324991
      328987 332984 336987 346984 355980 365973 372966 376963
      382961 388959 392962 402968 412965 418962 422959 428950
      433941 439929 445921 452911 455904 456901 459899 462899
      464897 469893 473881 477869 480864 484859 487854 489848
      491843 493838 492824 492817 493815
 0.01 477686 476676 473670 469667 465667 461673 459679 453690
      450694 448701 446707 450711 457722 459729 460733 462735
      468735 471731 473723 473715 472705 474700 477686
 0.01 484120 484119 483118 482116 481117 482120 483123 484120
 0.01 453120 453117 452116 450116 450117 449119 450120 451120
      453120 453120
 0.01 449056 448048 446043 445036 440031 437028 430027 428032
      431037 434042 434047 435050 437055 442058 447058 449056
 0.01 429068 430063 428061 423055 415047 407047 402049 399051
      397051 393051 391048 391037 391032 390029 388021 385015
      379003 375999 373996 369996 363998 360003 359012 360020
      365035 367041 368044 364044 357046 352050 350055 351058
      355059 368066 373069 376075 381079 383078 384074 385070
      388068 393065 399063 407064 419069 427070 429068
 0.01 409103 410098 408096 406095 404098 404100 404104 402108
      400110 398110 396112 398113 401113 403112 405110 407108
      408105 409103
 0.01 384200 384197 382195 379193 376191 374190 373188 369187
      368190 371191 372193 375195 377197 380198 382200 384200
 0.01 322885 322874 319868 315866 314868 313877 312886 310894
      309903 309908 312910 315905 318897 321890 322885
 0.01 267800 266796 264795 261795 258794 256795 253797 251798
      249800 248802 248806 251807 252805 256804 257802 261802
      265801 267800
 0.25 502144 501142 499140 497138 494135 492135 491135 487135
      487138 489140 490142 493143 497144 500146 502144
 0.25 500906 501901 500896 497892 492896 488900 485905 482909
      479915 479922 481925 484926 491925 494921 496919 497914
      499909 500906
 0.25 481832 481821 481817 478815 475816 469821 461827 451833
      441839 435842 431842 429840 422831 419826 415823 409823
      404825 400830 397831 394831 395825 398820 401816 408814
      412810 414806 415802 413798 410794 401789 396786 390785
      385783 383775 380768 378760 380745 373737 368728 361719
      353713 349712 347714 344719 343733 343741 345746 347747
      352750 354751 355755 355760 355769 356782 358795 355801
      355806 356811 356819 354825 349835 346840 344843 342845
      338845 334847 333850 331855 331862 330870 331874 333875
      340872 341877 340887 337898 333910 328924 325939 321950
      320956 318962 314971 301990 293999 285007 277016 274020
      273026 277029 283027 288025 292022 296011 304004 308000
      310994 313988 318984 322981 326976 328971 332967 339972
      345975 348976 353971 355967 359962 363960 368956 370952
      377941 384931 389932 393934 398937 404936 407933 410933
      411935 414943 415945 418947 426938 432928 439917 444904
      450894 456884 460875 466865 473853 476848 478843 481832
 0.25 479969 478967 477966 476965 474967 473969 474970 476972
      477971 479969
 0.25 404845 402845 400844 399845 398846 399846 400848 402847
      404846 404845
 0.25 376033 376030 377028 376026 376024 376021 375020 375019
      374017 372017 370017 369019 369021 368023 368025 369028
      370029 370030 371032 371033 373034 375034 376033
 0.50 473843 473833 468831 460837 455840 450840 446842 441846
      439848 439851 445852 448852 448855 446860 442866 440871
      441877 439885 437892 434897 431900 424902 420906 417913
      420928 417934 417938 420938 423935 426931 433919 438909
      445898 448892 449884 454873 460862 468853 473843
 0.50 421841 421837 419834 417833 415832 413830 410830 410833
      410836 412840 414842 416844 418846 421844 421841
 0.50 419872 420867 419864 418860 417857 415855 411854 408857
      407859 408864 409867 410870 412872 414874 418874 419872
 0.50 408805 406801 402800 397796 394794 390795 382798 380801
      378805 380810 382811 383822 386825 388824 393817 398811
      403808 408805
 0.50 406889 406885 404879 398872 394865 392861 389858 386856
      385851 382847 379845 374850 372853 368853 364832 362827
      360828 357831 355835 354848 351855 348863 345873 341892
      336910 331930 330939 327949 327952 330955 336955 338958
      341965 346972 350971 352967 357959 365956 369949 385918
      389917 393918 396921 398918 396908 394898 394895 395892
      400895 405892 406889
 0.50 376758 376755 376753 375751 374749 374748 372747 371747
      370747 369748 368748 367750 367752 368755 368757 369759
      370760 371761 372762 374761 374760 375759 376758
 0.50 373803 372801 370799 368800 367801 366802 365804 365805
      365807 366809 368811 369810 371809 371808 372806 372805
      373803
 0.50 371819 370817 368815 366813 365813 364814 363816 363818
      362820 363823 363825 365824 367824 369823 370822 370821
      371819
 0.50 359734 357730 355730 354731 352730 350732 349729 348726
      347729 347733 346736 347741 349742 351742 353742 356739
      358736 359734
 1.00 378918 379903 377891 375886 372882 366876 362872 359869
      355870 352875 348883 345893 341903 339915 337925 336931
      337939 341941 343946 344958 346963 350963 355955 360946
      361951 361954 364952 366947 370937 375929 377925 378919
      378918
 1.00 353925 352923 351925 350928 352930 352929 353927 353925
      353925
 1.50 371916 372909 371902 369891 359877 355879 352883 349891
      346901 344911 341921 340925 340932 344941 347949 347956
      350959 352956 353949 352944 348941 346931 346921 348915
      351913 355912 359908 362906 366907 369915 371916
 2.00 365894 363889 360885 359880 356883 354886 352890 350895
      349899 350903 353906 356903 358901 362897 365894
 3.00 355896 356892 356891 355892 354894 355896

$$




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