Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 230637
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
136 AM EST MON JAN 23 2017


PRELIM DAY 1 QPF DISCUSSION
VALID JAN 23/1200 UTC THRU JAN 24/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...EASTERN U.S...

AN UPPER LOW CENTERED IN NORTHWEST GEORGIA WAS IMPRESSIVELY WOUND
UP AT 06Z...WITH A SPIRAL PATTERN TO RADAR REFLECTIVITY. THE LOW
WAS EMBEDDED IN A GENERALLY PROGRESSIVE PATTERN...BUT AT SUCH
INTENSITY AND BEING OF MEDIUM WAVELENGTH...PROGRESS TOWARD THE
EAST AND NORTHEAST WILL BE SOMEWHAT SLOW...LEADING TO A WIDESPREAD
PRECIPITATION SHIELD AFFECTING THE EASTERN / NORTHEASTERN U.S.
THROUGH DAY 1 AND INTO DAY 2. AT THE SURFACE THE OCCLUDED AND
STACKED LOW BENEATH THE TIGHT UPPER VORTEX WILL GRADUALLY HAND OFF
TO COASTAL LOW DEVELOPMENT OFF NORTH CAROLINA/VIRGINIA BY MONDAY
AFTERNOON. INVERTED TROUGHING WILL DEVELOP WITHIN THE SLOPED COLD
AIR TO THE WEST...LINING UP A SYNOPTICALLY FORCED PRECIPITATION
BAND JUST TO THE LEE OF THE APPALACHIANS AND EXTENDING UP INTO NEW
YORK STATE. WARM ADVECTION AND DIFLUENT UPPER LEVEL FLOW WILL FILL
IN THE PIEDMONT AND COASTAL PLAIN WITH PRECIPITATION IN BETWEEN
THE MID LEVEL INVERTED TROUGH AXIS AND THE SHORELINE...YIELDING A
FAIRLY CONTINUOUS AREA OF 1 TO 2 INCH AVERAGE LIQUID ACCUMULATIONS
FROM VIRGINIA TO NEW ENGLAND THROUGH TUESDAY MORNING. A SWATH OF
EVEN HEAVIER RAINFALL WILL LIKELY AFFECT THE COASTAL MID ATLANTIC
AND NEW ENGLAND FROM MARYLAND TO MASSACHUSETTS...AS THE COASTAL
CYCLONE IS FORECAST TO UNDERGO A PERIOD OF INTENSIFICATION WHEN
THE UPPER TROUGH SWINGS INTO A SLIGHT NEGATIVE TILT MONDAY NIGHT
AND TUESDAY MORNING. THIS WILL PRODUCE A STRONG EASTERLY FETCH OFF
THE ATLANTIC DIRECTED INTO NJ/NY/CT/RI/MA.

THE PREVIOUS WPC FORECAST HAD MUCH OF THIS HANDLED WELL. THE MAIN
TREND WAS TO ELONGATE THE INVERTED TROUGH AXIS FARTHER INLAND AND
TO KEEP HEAVIER PRECIPITATION DOWN ACROSS VIRGINIA FOR LONGER
DURATION GIVEN THE DEPTH OF THIS SYSTEM. MUCH OF THE GUIDANCE ALSO
HINTS AT A MINOR SEPARATION BETWEEN THE INVERTED TROUGH AND THE
MORE INTENSE EVENT ALONG THE COAST...SO WE LOWERED AMOUNTS OVER
EASTERN PA/MD UP TO BINGHAMTON...ALTHOUGH THESE AREAS ARE STILL
EXPECTED TO RECEIVE AREAL AVERAGE PRECIPITATION GREATER THAN AN
INCH. THERE WILL BE A VARIETY OF PRECIPITATION TYPE CHALLENGES AS
WET BULBING AND DYNAMIC COOLING BRINGS THE POTENTIAL FOR ICE AND
SNOW IN AREAS INLAND AWAY FROM THE I-95 CORRIDOR. PLEASE SEE THE
WPC HEAVY SNOW DISCUSSION...QPFHSD...FOR DETAILS.


...WESTERN U.S AND NORTHERN PLAINS...

THE PLUME OF ENHANCED MOISTURE AND VERY STRONG ONSHORE FLOW THAT
HAD BROUGHT FLOODING TO SOUTHERN CALIFORNIA ON SUNDAY...WILL
PROGRESS INTO THE DESERT SOUTHWEST ALONG WITH A PRONOUNCED FRONTAL
PASSAGE THAT WILL FINALLY SIGNAL THE...AT LEAST FOR SEVERAL
DAYS...END TO THE STORM PATTERN AFFECTING THE WESTERN STATES. SOME
OF THE HEAVIER DAY 1 PRECIPITATION...THEREFORE...WILL OCCUR EARLY
MONDAY IN THE MOUNTAINS EAST OF SAN DIEGO...AND THEN FOR MUCH OF
THE MIDDAY TO EVENING HOURS IN THE FAVORED AREAS OF ARIZONA AND
SOUTHWEST UTAH. ADDITIONAL RAINFALL OVER 1.5 INCHES IS POSSIBLE IN
THE HIGH TERRAIN ALONG FAVORED SLOPES...WHILE 0.50 TO 1.25 INCH
AMOUNTS WILL BE MORE COMMON. ELSEWHERE THIS FRONTAL SYSTEM AND
ASSOCIATED HEIGHT FALLS WITHIN THE PROGRESSIVE AND POSITIVELY
TILTED UPPER TROUGH...WILL AGAIN SUPPORT MEANINGFUL PRECIPITATION
FROM BORDER CANADA TO MEXICO...WITH AMOUNTS BEING SOMEWHAT MORE
ENHANCED...0.50-INCH AND GREATER AREAL AVERAGE...IN THE EXPECTED
LOCATIONS OF THE WASATCH AND CENTRAL ROCKIES. WE ALSO EXPANDED
COVERAGE OF MEASURABLE PRECIPITATION THROUGHOUT CENTRAL NEVADA
BASED ON MODEL CONSENSUS AND ANALOG DATA FROM THE GEFS REFORECAST.
WPC QPF WAS BASED ON NUDGING THE PREVIOUS FORECAST TOWARD THE NAM
AND NAM CONUS NEST FOR THEIR RESOLUTION.

AS THE SYSTEM PULLS OUT INTO THE PLAINS THE DEVELOPING
PRECIPITATION STRUCTURE TUESDAY MORNING MAY INCLUDE A LOT OF
MESOSCALE DETAIL AS THE COLUMN BEGINS TO SATURATE IN THE FACE OF
STRONG ASCENT AND DEVELOPING LEE CYCLOGENESIS. MUCH OF THE
GUIDANCE...NAM/ECMWF/UKMET...TO NAME A FEW...DEPICT MORE THAN ONE
SWATH OF FRONTOGENETICALLY FORCED PRECIPITATION OVER THE NORTHERN
HIGH PLAINS. BASED ON GFS AND ECMWF MASS FIELDS IT LOOKED AS
THOUGH THE NAM AND NAM CONUS NEST QPF WAS WELL PLACED AND A LITTLE
MORE GENEROUS THAN SOME OF THE GLOBAL MODEL QPFS...WHICH SEEMED
REASONABLE GIVEN THE STRENGTH OF THE DEVELOPING SYSTEM. WE NUDGED
TOWARD THE NAM AND NAM CONUS NEST...WHILE NOTING THAT THE 00Z
WRF-ARW ALSO LENDS SUPPORT TO THIS APPROACH...THOUGH CONFIDENCE IN
THE DETAILS IS NOT PARTICULARLY HIGH.

BURKE

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

24HR QP VT 24/12Z
 0.01 522227 524219 522216 517213 512212 509212 506210 503202
      508153 510147 511137 505124 502117 499110 496103 492094
      485075 484072 480072 478074 476073 474071 471068 467067
      464066 463062 462059 462054 467048 469040 470029 471021
      472010 472001 470993 466986 462981 455976 450975 446973
      440968 435961 430958 427956 424958 421959 419961 416968
      417974 417982 418991 417998 414006 412010 410014 402023
      401037 401044 399047 396048 388048 381046 372045 367046
      360048 352049 339051 329050 325055 325058 326060 328062
      332063 335064 337066 333070 326074 323077 319080 312082
      304084 299087 298091 299095 299103 300107 299112 299116
      301119 304123 309126 311129 310133 310138 308140 305143
      301142 296138 291137 288139 287143 288148 292156 295163
      300169 303174 310179 319188 323192 325197 327203 331210
      339219 346231 358246 362252 369257 381265 388269 396271
      402271 407273 412277 419277 425276 432274 435266 439266
      441269 447276 452278 455281 463286 468293 471291 476283
      475265 474259 470254 467249 461243 457238 449236 446238
      443237 438235 436232 433229 429226 431221 435220 441222
      444220 444213 442206 441197 440178 440171 440163 444156
      447148 453135 460134 462136 461138 460143 459153 456157
      457161 460163 464164 468172 471179 476179 482176 484174
      484177 485182 487199 488206 492212 495219 497222 501224
      508225 514229 517230 520229 522227
 0.01 513840 512830 507823 495819 492820 488818 483819 470821
      457816 453814 449809 450802 452796 457786 461768 465762
      468757 472743 473727 473718 471710 468703 465697 462693
      458689 455685 452678 446659 443652 439646 434644 427646
      420648 415652 404659 399662 395667 387675 379682 372695
      365706 355713 344720 332726 323731 319733 315737 308747
      300760 297761 293762 288759 273759 262762 250764 240769
      231776 227780 227789 228799 232806 236812 237815 236818
      236825 237830 239832 245832 249827 251824 256825 265833
      269835 273834 279834 284831 285829 285825 285819 283816
      277813 270812 264811 259810 254808 251806 252803 260796
      268791 275789 280787 289785 296784 299786 300792 301796
      306796 314796 317797 319799 320806 321810 320814 318826
      320830 324834 329833 333831 343823 348823 349826 341842
      341845 341849 344857 353864 358866 364865 371864 374863
      379862 385861 391859 396858 401856 407855 411853 418854
      425859 430862 436864 448867 455867 460869 465868 471865
      478863 484862 489861 493859 502853 510847 513840
 0.01 482166 482163 481161 481160 481158 480155 479157 479160
      479162 479164 480165 481167 482166
 0.01 480152 479150 478145 478142 477139 477134 474131 472136
      470136 467137 466139 467142 470144 473145 475146 476149
      478152 480152
 0.01 412200 412193 411185 409181 408180 401177 396180 392181
      389183 388187 390193 395197 400200 407202 410202 412200
 0.01 370174 371170 370167 369165 365163 362162 358161 355161
      353162 352165 354168 354171 355173 358175 362175 365176
      367176 370174
 0.01 332151 332149 332147 331144 331142 330140 328139 327139
      326140 324141 322143 321145 320147 321149 323150 325151
      327151 328152 330152 332151
 0.25 468270 468266 467262 466259 464256 462255 459253 456254
      454256 454260 456263 457265 459267 461270 463272 465272
      468270
 0.25 472840 468836 464834 457834 450833 445833 445835 447838
      451843 454846 460848 465849 470847 472840
 0.25 457727 457719 454714 448709 445701 443692 440683 437676
      433669 428664 425662 420662 415663 411665 397672 391676
      386681 379692 370707 360717 355721 350725 335731 326736
      320741 316746 315749 314752 317758 316766 313772 316774
      320774 325772 331772 340770 343771 344776 342782 340790
      340793 338798 338804 341805 343804 344798 344792 347790
      354777 355773 354769 349765 351760 353759 360756 364757
      367760 367770 366779 367789 368798 368806 367811 364813
      361816 358820 355824 352832 350840 350843 353844 367845
      381841 390838 399836 406833 413830 422820 427815 429809
      443777 446770 450763 453757 454750 455735 457727
 0.25 461030 462022 462016 460006 457004 455005 452008 447015
      445020 442023 434026 431029 430035 432040 436042 442042
      446043 450045 453044 457040 459036 461030
 0.25 451102 452096 450091 448088 446087 445087 445082 449077
      448073 445070 443069 441071 436083 434087 430088 427082
      425079 424074 426067 426060 425058 421057 413057 406054
      401055 398057 390059 379060 374056 370052 364052 359055
      364070 368084 371089 372092 372095 370101 366105 362112
      358112 356110 352104 349098 355095 360093 362091 362088
      357082 354081 351083 346085 342086 340084 336082 332081
      330083 328091 325096 320104 318111 317116 319118 324118
      328119 334121 337125 340131 344136 350141 356142 363140
      370142 375146 379146 383146 384144 384136 386132 389128
      394125 401125 406123 412127 414132 417139 417145 418156
      420159 424161 426160 428156 432151 434145 436136 437129
      441120 447109 451102
 0.25 422255 424249 425244 421238 416227 413219 408216 403214
      399209 392206 385204 378201 380197 377189 373184 368182
      361180 355182 353184 353188 357192 363195 366197 367200
      365203 358203 355200 350196 348197 347201 346205 346208
      348214 350221 353227 360236 364241 371245 378246 385249
      392252 399254 410260 415260 418259 422255
 0.25 429195 430192 430190 430188 430187 429185 428185 427184
      426187 426189 427192 428193 428194 429195 429195
 0.25 441830 440827 439827 438827 437828 438828 439830 440830
      441830
 0.25 434999 436993 434990 430994 426001 423009 423020 419029
      417036 418040 421038 424030 427020 430013 432006 434999
 0.25 403100 403097 403096 402095 402093 401091 400090 398092
      397094 397097 399099 400102 401102 402100 403100
 0.25 393107 392103 392100 390096 389094 386095 384097 383099
      381103 381108 382110 385113 389111 391109 393107
 0.25 343180 345173 345168 342164 338162 329159 321155 312152
      307151 304153 304157 307162 312167 320172 327178 332180
      334182 337185 340183 343180
 0.25 282771 279767 274767 261769 248771 239775 235779 234784
      234791 236798 240801 244802 251795 254791 258789 266783
      275777 280774 282771
 0.50 449736 440708 440702 438693 437688 434684 429678 425675
      417670 412671 406672 396676 390680 387684 381694 375703
      369711 353727 341732 332737 327740 325747 329760 333762
      340760 348755 354751 359749 369751 373754 374761 373772
      371781 373790 376804 376811 373816 372821 369825 367833
      368836 369834 372829 373823 388827 400822 411818 415815
      418811 424803 434780 440769 443759 449736
 0.50 456027 457025 457023 456021 454022 453025 452027 452029
      452031 454031 454030 456029 456027
 0.50 439108 438104 436102 430100 424110 421112 418113 412111
      409106 407103 405105 400109 396111 394114 394117 398117
      409120 415124 418128 421131 422134 423140 427138 428136
      429132 429127 428124 429121 431116 435111 439108
 0.50 416249 417243 415240 412240 410239 411227 409224 407225
      399226 392226 385223 379222 373216 368215 359214 356216
      357220 364232 367235 370234 375232 386241 393246 399249
      408253 412252 415250 416249
 0.50 402074 402070 401068 396067 392066 389066 387070 387075
      387082 384083 381084 380082 377079 375082 377086 378097
      382090 387088 391088 395090 397087 398080 400076 402074
 0.50 397101 396099 396097 395096 394094 392094 392096 392097
      392098 393100 394101 395102 397101
 0.50 373193 373191 373190 371188 369186 368185 367185 366184
      364184 363183 361183 359184 358185 358187 359187 360188
      362189 363190 365191 366191 367192 369192 370193 372193
      373193
 0.50 377132 377130 378128 378126 377124 376123 375122 374121
      372122 371122 371124 371127 371128 371129 372131 372133
      373134 374136 375134 376134 377132
 0.50 375069 375066 375065 374064 373063 371062 370062 368063
      369066 371068 373070 374069 375069
 0.50 367124 368122 367120 366119 365119 363118 362119 361119
      360120 360123 361124 362125 364125 366125 367124
 0.50 362825 363823 361822 360823 359823 358825 356828 355830
      354833 353834 353835 353837 353839 355839 357837 358834
      359834 359832 360830 361827 362826 362825
 0.50 357122 356117 353113 347107 343100 342094 338091 335092
      334093 332097 329101 326102 324107 326111 329114 333115
      338117 341120 343129 346132 349132 352128 355124 357122
 0.50 343173 343169 341167 336164 329162 324159 319157 312156
      310158 311160 315165 320168 326172 331174 336177 340177
      341175 343173
 0.50 271775 269772 265772 256774 249774 243777 239781 237786
      237790 238793 240796 244798 246797 251791 256787 261782
      268777 271775
 1.00 433706 432697 429694 423689 417684 410680 406679 400679
      395680 391683 382697 377706 371713 366718 361724 348738
      356739 364741 369743 373743 380741 384744 385748 387754
      389756 396755 400757 402761 402764 397770 393773 391773
      386771 382773 379778 378782 378787 379790 386795 389794
      395792 398790 401787 409783 412781 417780 420782 424782
      429774 431769 432765 432755 427753 424748 424741 425736
      429728 430718 433706
 1.00 347747 345747 343749 342750 342751 344750 347748 347747
 1.00 346112 346111 345109 344108 343107 343106 341105 339106
      339107 338108 339109 340110 342111 344113 346113 346112
 1.00 335169 336167 334166 332165 330165 329164 328163 327163
      326163 325163 324165 325166 326167 326168 328169 330169
      332170 333170 335169
 1.50 429704 427699 424697 415696 411695 409691 403686 399684
      395684 389690 384697 381705 378710 375713 370718 365727
      364732 367735 370736 375737 384733 389732 393732 395736
      396742 400746 403746 408746 411744 415739 417735 419726
      421721 423717 425714 428709 429704
 1.50 422770 421768 419768 417769 415769 417769 419770 420771
      421771 422770
 1.50 403776 402776 400776 400778 402777 403776
 2.00 426705 421701 415704 410709 406716 402723 401727 402732
      407737 410735 411730 414723 417717 423711 426705
 2.00 400704 399697 397692 393691 390694 384701 383711 375716
      370723 369728 372731 376732 381730 387724 393718 396717
      397715 395712 397707 400704

$$




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