Quantitative Precipitation Forecast
Issued by NWS

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925
FXUS04 KWBC 300702
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
301 AM EDT SUN APR 30 2017


PRELIM DAY 1 QPF DISCUSSION
VALID APR 30/1200 UTC THRU MAY 01/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...HEAVY RAIN IN THE SOUTHERN U.S...

RAINFALL BETWEEN 5 AND 9 INCHES WAS OBSERVED IN EASTERN
OKLAHOMA...SOUTHERN MISSOURI...AND NORTHWEST ARKANSAS SATURDAY.
LIGHT TO MODERATE RAIN WILL CONTINUE THROUGH SUNDAY MORNING IN
PARTS OF THAT REGION. HIGH-END FLOODING WAS ONGOING AND WILL
CONTINUE WELL AFTER THE RAIN CEASES. MEANWHILE...THE THREAT OF
ADDITIONAL FLOODING WILL MOVE DOWNSTREAM INTO EASTERN
ARKANSAS...MUCH OF MISSISSIPPI...AND ADJACENT PARTS OF LA/MS/TN.

THE PARENT SYNOPTIC LOW WAS TRULY IMPRESSIVE...WITH BROAD COVERAGE
OF 2.5 TO 3.5 STANDARD DEVIATION COLD HEIGHTS AT 500 MB OVER THE
CENTER OF THE NATION. THE SYSTEM WAS GRADUALLY REACHING ITS MATURE
PHASE...AND WILL LIFT NORTH AND EASTWARD...ALLOWING A COLD FRONT
TO ACCELERATE SOMEWHAT. THIS FORWARD MOTION WILL LIKELY PREVENT
ANY FURTHER EXTREME RAINFALL TOTALS...THOSE ABOVE 7 INCHES. THE
ONE EXCEPTION COULD BE EARLY THIS MORNING DURING THE PEAK OF THE
LOW LEVEL JET CYCLE OVER ARKANSAS AND PERHAPS ADJACENT NORTHERN LA
/ WESTERN MS / WESTERN TN. EVEN WITH THE INCREASED FORWARD MOTION
OF THE CONVECTION...HOWEVER...PREMIUM GULF MOISTURE WITH A
TROPICAL CONNECTION...FLOW EMANATING FROM THE CARIBBEAN...WILL
MAINTAIN VERY HEAVY SHORT TERM RAIN RATES...DELIVERING AN AREAL
AVERAGE OF AT LEAST 1.5 TO 3.0 INCHES IN THE AREAS WHERE STRONG
CONVECTION IS EXPECTED THROUGH SUNDAY NIGHT.

THE STEERING FLOW WILL GRADUALLY PICK UP MORE WESTERLY
COMPONENT...AND GIVEN THE ONGOING WIDESPREAD CONVECTION...OUTFLOWS
WILL ALSO HAVE SOME INFLUENCE IN EXPANDING THE HEAVY RAIN
POTENTIAL EASTWARD TODAY. WE THEREFORE TRENDED THE QPF
EASTWARD...EXPANDING THE 1 TO 3 INCH 24-HOUR QPF TO MATCH THE
DEVELOPING MODEL CONSENSUS...WITH PARTICULAR EMPHASIS ON THE 00Z
GFS...WRF-ARW...AND GEM REGIONAL. WE LEANED ON THE HEAVY SIDE WITH
RESPECT TO MAGNITUDE...GIVEN THE QUALITY OF MOISTURE AND
INSTABILITY.


...RAIN/SNOW IN THE PLAINS AND UPPER MIDWEST...

A WELL FORMED BAND OF RAIN AND SNOW SHOULD BE MAINTAINED ALONG THE
TRACK AND NORTH THROUGH WEST OF THE TRACK OF THE MID LEVEL LOW AS
IT LIFTS THROUGH THE PLAINS. MODELS HAVE COME TO A FAIRLY STRONG
CONSENSUS FOR THIS LARGE SCALE AND STABLE FEATURE. ALTHOUGH THE
COUPLED JET STRUCTURE WILL BE LOST EARLY TODAY AS THE SYSTEM
REACHES MATURITY...IT WILL STILL BE A VERY STRONG STACKED SYSTEM
FOR SOME TIME TO COME...WITH SOME CONNECTION TO GULF MOISTURE
STILL COMING IN ON THE NORTHEAST SIDE OF THE LOW...AND
PRECIPITABLE WATER VALUES A RESPECTABLE 0.50 TO 0.80 INCHES ALONG
THE DEFORMATION BAND. THIS WILL YIELD SOME IMPRESSIVE LIQUID
TOTALS ALONG A SWATH OF MODERATE WIDTH FROM WESTERN KANSAS TO
SOUTHERN AND CENTRAL MINNESOTA. WPC TOOK THE PREVIOUS FORECAST AND
NUDGED IT TOWARD THE LATEST OVERALL CONSENSUS...WITH SLIGHT
EMPHASIS ON THE 00Z GFS. THE RESULT WAS TO INCREASE AMOUNTS OVER
NORTHWEST KANSAS / SOUTHERN NEBRASKA...AND TO SHARPEN THE GRADIENT
ON THE NORTH SIDE OF THE PRECIPITATION OVER SD/MN. PLEASE SEE THE
WPC HEAVY SNOW DISCUSSION FOR DETAILS ON PRECIPITATION TYPE AND
SNOW ACCUMULATION.


...RAIN IN THE GREAT LAKES...

THROUGH A COMBINATION OF WARM ADVECTION...FRONTOGENESIS...AND
ASCENT ON THE SOUTHWEST FLANK OF A BROAD UPPER LEVEL JET
STREAK...RAIN MAY BE MORE OR LESS CONTINUOUS ACROSS WESTERN AND
CENTRAL MICHIGAN TODAY...INCLUDING ACROSS LAKE MICHIGAN TO
NORTHERN ILLINOIS. IT WILL BE DIFFICULT FOR MUCH INSTABILITY TO
DEVELOP HERE...BUT DEEPLY SATURATED PROFILES NORTH OF A WARM FRONT
WILL SUPPORT HEALTHY RAINFALL AMOUNTS IN THE 1.0 TO 2.5 INCH
RAIN...ON AVERAGE. SOME INSTABILITY WILL LIKELY DEVELOP A LITTLE
FARTHER SOUTH AND WEST...INTO WESTERN AND SOUTHERN ILLINOIS...AND
FEEDING UP INTO SOUTHEAST IOWA...JUST AHEAD OF A TRIPLE POINT LOW.
THE WPC QPF EMPHASIZES THIS AREA DURING PEAK HEATING EARLY THIS
EVENING. STRONG ASCENT WILL SUPPORT REASONABLY HEAVY RAINS DOWN
INTO KENTUCKY AND OVER INTO INDIANA AND PART OF OHIO
TODAY...ALTHOUGH THE STRONGER INSTABILITY AND HEAVIEST RAINS WILL
LIKELY OCCUR OVER THE SOUTHERN U.S. THE WPC QPF WAS DERIVED BY
NUDGING CONTINUITY TOWARD THE 00Z GFS...WRF-ARW...AND GEM REGIONAL.


...PACIFIC NORTHWEST...

WPC TOOK A CONSENSUS APPROACH TOWARD LIGHT TO MODERATE
PRECIPITATION ACCOMPANYING A LOW AMPLITUDE TROUGH.

BURKE

GRAPHICS AVAILABLE ON THE WEB AT
WWW.WPC.NCEP.NOAA.GOV/QPF/QPF2.SHTML


24HR QP VT 01/12Z
 0.01 534206 537192 538185 538177 536166 532157 527147 523135
      521130 517126 510120 507117 505112 503101 504096 506092
      503083 501070 500063 500053 502047 505042 507038 507031
      503023 500021 496020 491020 488022 484022 480025 472030
      462030 451029 443031 440033 438037 438044 439048 442057
      442061 438064 434071 436076 434078 432084 426092 421105
      419107 419113 419118 422121 429123 432121 438120 441120
      442123 445124 444128 442131 441141 436153 436156 437160
      438162 440166 441171 443182 445191 446196 449196 456192
      464185 470178 474176 478178 482186 491188 493192 494197
      495201 494203 488202 453212 444211 437213 430216 427218
      425223 423231 423235 421238 419242 418247 422252 428252
      434247 441244 446243 450245 458246 469249 474252 473260
      476264 480268 490270 493273 497272 500269 501262 502255
      504251 508241 509233 509226 508219 506213 510216 513221
      516222 521222 526223 530220 533214 534206
 0.01 504208 503205 502202 500204 500206 501208 503209 504208
 0.01 494238 493235 491233 490232 488231 486231 485233 486235
      488235 488236 489237 491238 492238 494238
 0.01 493736 492731 491727 489716 487709 485697 471668 469664
      466663 461658 455653 451654 448657 444658 442660 439669
      435688 433696 432704 431707 432713 434720 435725 431727
      427732 424738 423744 418745 415746 413748 410756 408768
      402773 398771 393772 387778 384785 383791 378791 372793
      366797 362802 356805 355801 356798 355796 352794 348795
      346797 342796 339797 332802 329809 331813 327819 317823
      313824 307824 303823 299822 292819 287816 283810 284807
      287808 287806 285805 280802 274800 267799 262800 259803
      256803 254805 257812 260815 263815 264810 267811 270813
      273814 272817 272821 274824 280828 287830 290831 294831
      300832 307833 315833 321830 329829 336826 340826 340830
      337833 333836 322837 314838 310837 305837 301836 298838
      293843 290849 285855 276863 271867 268872 264876 262879
      261884 260890 259895 256898 260914 262918 259922 257925
      256930 254935 257942 274942 303938 320937 326936 336935
      350933 360932 366936 373941 376942 376945 377951 378956
      380961 379967 377971 369982 362992 354002 353012 352018
      354020 358026 359029 364030 371033 377033 381032 394027
      402023 405022 409019 429005 440998 444994 452992 458989
      462986 474975 484960 488952 491942 493933 494924 494901
      495899 495893 495883 493877 493872 492858 491832 489802
      488792 489780 491759 492754 491746 493736
 0.01 486106 485103 485100 484098 482098 480098 479099 480102
      482104 483105 485108 486106
 0.01 488078 488073 486070 482070 479069 477067 477059 480052
      478050 477051 475054 473059 471063 471068 470078 473081
      476081 483082 488078
 0.01 461233 461230 458227 456225 453225 451227 449229 447229
      444230 445234 448235 450234 453234 455233 459234 461233
 0.01 432186 432185 430185 430188 432186 432186
 0.01 435172 435167 433164 432159 427153 424150 422148 421143
      420142 418149 415156 414160 415163 419164 422169 425175
      430174 435172
 0.01 427187 427184 425186 425187 427187 427187
 0.01 419723 419716 417710 416705 413701 410699 407702 406705
      408710 409716 408723 409728 411731 415732 417729 419724
      419723
 0.01 417071 417066 416062 413057 406051 400052 395055 389061
      388070 392077 397081 401082 405081 411078 415073 417071
 0.01 409129 409124 408121 408117 409112 409108 407105 405107
      403109 401111 399113 399118 399120 400123 402127 403128
      407129 409129
 0.01 403808 398807 392808 387809 383809 380807 377805 374806
      372810 370815 371818 374819 379818 384817 388815 393812
      396811 401810 403808
 0.01 251808 249802 248799 246796 242793 239789 235785 232785
      231788 230790 230794 231798 232800 235806 237812 240817
      246818 248817 249813 251808
 0.25 497255 497253 495252 494254 495257 496257 497255
 0.25 482216 480213 479216 480217 482216 482216
 0.25 487139 485137 485136 484135 482134 481134 479134 477134
      476135 474136 475138 477139 479138 480138 482138 484138
      485139 487139
 0.25 475715 475707 473701 469690 467687 462684 457682 454680
      451681 450684 449692 447707 446739 441762 439773 433783
      430786 424791 420794 418797 417802 414812 411818 408822
      399827 391832 368836 355840 348842 342845 337847 331848
      320853 310855 300858 292862 283869 277875 269883 265895
      266904 269909 272911 274916 270925 270929 275930 279932
      286932 299931 313928 337922 357917 367915 378913 383914
      387918 391923 394931 396937 395947 393959 384978 380988
      374997 372002 370010 372016 376021 380024 386023 395020
      427999 445986 452978 460969 466962 471953 475943 477938
      479932 478915 476908 475897 477891 477886 476882 475873
      475862 476857 476848 476835 475819 476802 476785 477767
      478751 478742 477732 475715
 0.25 472161 473158 473156 472154 472153 471152 469150 467149
      466148 464147 462147 461148 460150 460151 460153 460155
      461158 461159 463160 465160 466161 468162 469162 471161
      472161
 0.25 404790 403789 402788 401788 399787 398786 396784 394783
      392783 390785 390787 390790 391792 393793 395793 396793
      398793 400792 402791 403791 404790
 0.50 471738 470722 468707 464697 457689 455689 453691 452696
      450703 449711 450730 449746 445768 442780 439792 434804
      431809 428811 425809 422805 418809 414819 410828 407832
      404834 402833 379838 366840 355844 348846 343849 333852
      322855 313858 304862 295868 279879 274883 272889 271898
      274904 277908 281909 284914 282918 279922 279927 284928
      291928 303926 314923 339915 357910 367907 377903 382901
      389901 394904 397911 403919 405922 405929 404941 402952
      399963 393973 388982 383992 381999 379007 380014 382016
      386017 392017 397016 404012 420001 436990 441985 445981
      453971 458963 463955 472935 473927 472919 471908 470899
      468893 465886 463881 463876 465864 467851 468845 468838
      466822 467808 470793 471775 472761 471738
 0.50 456891 456888 454886 453887 451889 448890 444890 443894
      442897 442901 443904 446905 448902 450900 452898 454896
      455893 456891
 1.00 465742 464730 461720 459710 457707 456704 454705 453715
      455729 452752 450770 448780 445790 440811 433828 429836
      425843 415856 403870 403862 408855 408851 406847 400844
      398842 394840 386845 383848 385852 383856 378858 377856
      376852 376847 372844 368843 305871 296882 296886 293889
      288895 286902 294901 295905 294910 297920 302921 307920
      314919 330915 347910 357906 365902 372898 378893 390884
      397879 401876 404876 406880 406885 406896 408901 412902
      417897 420890 427884 432878 439872 452859 456852 458844
      459837 458832 460820 461809 463797 464791 465784 465772
      465742
 1.00 466932 466922 466917 465913 461914 458916 453920 447922
      439921 433920 428916 422912 420910 418912 417916 417922
      417926 419930 421931 422935 419941 416947 419952 414962
      410969 406975 398983 393989 390995 389000 389004 390007
      393009 398009 406005 426992 435985 440980 445974 451963
      455957 459950 462942 466932
 1.50 460775 458771 455773 452787 449796 446802 445809 444815
      442819 436828 432838 426848 421856 416868 412876 412880
      414882 416883 420881 424877 431870 437863 441859 444853
      447843 450838 451831 457805 458794 460778 460775
 1.50 457942 456939 453936 450935 447940 444940 441943 437953
      430957 424965 415981 411988 407991 403991 399993 397997
      399000 403000 409994 417990 424987 431982 437976 442968
      452953 457942
 1.50 398853 398851 397848 396848 395849 394850 393851 393853
      392856 394857 395855 396855 397854 398853
 1.50 378886 377883 374883 369885 362889 358889 356888 356885
      359880 366869 365855 367852 367849 363848 356849 351851
      345855 340859 331865 321874 312880 308884 304890 304895
      309897 308909 305913 304915 304918 312918 319916 331913
      344909 354903 363896 372892 376889 378886
 2.00 448826 448820 445824 443827 440832 438835 436840 434845
      432849 434850 437847 439843 441839 443835 446831 448826
      448826
 2.00 432971 431970 430971 429973 427975 428976 431973 432971
 2.00 430859 431855 427854 425856 424858 422861 422865 421867
      419872 419874 421875 423873 424871 426869 428865 429862
      430859
 2.00 359874 360868 358864 357858 359852 355852 352854 344859
      338863 330870 318880 313886 311892 315894 317898 321899
      315905 309911 306914 308917 318915 328913 336911 344907
      350902 353897 353894 351890 351887 357879 359874
 3.00 319913 317913 319913 319913 312913 310913
      312914 312913
 3.00 354877 350864 345864 342865 339868 338870 339873 333878
      329880 326883 321887 318894 322894 325891 331886 337882
      341882 339886 338890 339893 333898 329904 328907 331909
      337905 340902 342899 343895 345893 344889 347884 354877

$$





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